Merge drm/drm-next into drm-misc-next

Backmerging into drm-misc-next to get DRM accelerator infrastructure,
which is required by ipuv driver.
Signed-off-by: NThomas Zimmermann <tzimmermann@suse.de>

.clang-format

@@ -222,6 +222,7 @@ ForEachMacros:
   - 'for_each_component_dais'
   - 'for_each_component_dais_safe'
   - 'for_each_console'
+  - 'for_each_console_srcu'
   - 'for_each_cpu'
   - 'for_each_cpu_and'
   - 'for_each_cpu_not'
@@ -440,8 +441,11 @@ ForEachMacros:
   - 'inet_lhash2_for_each_icsk'
   - 'inet_lhash2_for_each_icsk_continue'
   - 'inet_lhash2_for_each_icsk_rcu'
+  - 'interval_tree_for_each_double_span'
+  - 'interval_tree_for_each_span'
   - 'intlist__for_each_entry'
   - 'intlist__for_each_entry_safe'
+  - 'iopt_for_each_contig_area'
   - 'kcore_copy__for_each_phdr'
   - 'key_for_each'
   - 'key_for_each_safe'
@@ -535,6 +539,7 @@ ForEachMacros:
   - 'perf_hpp_list__for_each_sort_list_safe'
   - 'perf_pmu__for_each_hybrid_pmu'
   - 'ping_portaddr_for_each_entry'
+  - 'ping_portaddr_for_each_entry_rcu'
   - 'plist_for_each'
   - 'plist_for_each_continue'
   - 'plist_for_each_entry'

.gitignore

@@ -20,6 +20,7 @@
 *.dtb
 *.dtbo
 *.dtb.S
+*.dtbo.S
 *.dwo
 *.elf
 *.gcno
@@ -38,6 +39,7 @@
 *.o.*
 *.patch
 *.rmeta
+*.rpm
 *.rsi
 *.s
 *.so

.mailmap

@@ -29,6 +29,7 @@ Alexandre Belloni <alexandre.belloni@bootlin.com> <alexandre.belloni@free-electr
 Alexei Starovoitov <ast@kernel.org> <alexei.starovoitov@gmail.com>
 Alexei Starovoitov <ast@kernel.org> <ast@fb.com>
 Alexei Starovoitov <ast@kernel.org> <ast@plumgrid.com>
+Alex Hung <alexhung@gmail.com> <alex.hung@canonical.com>
 Alex Shi <alexs@kernel.org> <alex.shi@intel.com>
 Alex Shi <alexs@kernel.org> <alex.shi@linaro.org>
 Alex Shi <alexs@kernel.org> <alex.shi@linux.alibaba.com>
@@ -227,6 +228,7 @@ Juha Yrjola <at solidboot.com>
 Juha Yrjola <juha.yrjola@nokia.com>
 Juha Yrjola <juha.yrjola@solidboot.com>
 Julien Thierry <julien.thierry.kdev@gmail.com> <julien.thierry@arm.com>
+Iskren Chernev <me@iskren.info> <iskren.chernev@gmail.com>
 Kalle Valo <kvalo@kernel.org> <kvalo@codeaurora.org>
 Kalyan Thota <quic_kalyant@quicinc.com> <kalyan_t@codeaurora.org>
 Kay Sievers <kay.sievers@vrfy.org>
@@ -286,6 +288,7 @@ Matthew Wilcox <willy@infradead.org> <willy@linux.intel.com>
 Matthew Wilcox <willy@infradead.org> <willy@parisc-linux.org>
 Matthias Fuchs <socketcan@esd.eu> <matthias.fuchs@esd.eu>
 Matthieu CASTET <castet.matthieu@free.fr>
+Matti Vaittinen <mazziesaccount@gmail.com> <matti.vaittinen@fi.rohmeurope.com>
 Matt Ranostay <matt.ranostay@konsulko.com> <matt@ranostay.consulting>
 Matt Ranostay <mranostay@gmail.com> Matthew Ranostay <mranostay@embeddedalley.com>
 Matt Ranostay <mranostay@gmail.com> <matt.ranostay@intel.com>
@@ -371,6 +374,8 @@ Ricardo Ribalda <ribalda@kernel.org> <ricardo.ribalda@gmail.com>
 Roman Gushchin <roman.gushchin@linux.dev> <guro@fb.com>
 Roman Gushchin <roman.gushchin@linux.dev> <guroan@gmail.com>
 Roman Gushchin <roman.gushchin@linux.dev> <klamm@yandex-team.ru>
+Muchun Song <muchun.song@linux.dev> <songmuchun@bytedance.com>
+Muchun Song <muchun.song@linux.dev> <smuchun@gmail.com>
 Ross Zwisler <zwisler@kernel.org> <ross.zwisler@linux.intel.com>
 Rudolf Marek <R.Marek@sh.cvut.cz>
 Rui Saraiva <rmps@joel.ist.utl.pt>
@@ -382,6 +387,7 @@ Santosh Shilimkar <santosh.shilimkar@oracle.org>
 Santosh Shilimkar <ssantosh@kernel.org>
 Sarangdhar Joshi <spjoshi@codeaurora.org>
 Sascha Hauer <s.hauer@pengutronix.de>
+Satya Priya <quic_c_skakit@quicinc.com> <skakit@codeaurora.org>
 S.Çağlar Onur <caglar@pardus.org.tr>
 Sean Christopherson <seanjc@google.com> <sean.j.christopherson@intel.com>
 Sean Nyekjaer <sean@geanix.com> <sean.nyekjaer@prevas.dk>
@@ -389,6 +395,7 @@ Sebastian Reichel <sre@kernel.org> <sebastian.reichel@collabora.co.uk>
 Sebastian Reichel <sre@kernel.org> <sre@debian.org>
 Sedat Dilek <sedat.dilek@gmail.com> <sedat.dilek@credativ.de>
 Seth Forshee <sforshee@kernel.org> <seth.forshee@canonical.com>
+Shannon Nelson <shannon.nelson@amd.com> <snelson@pensando.io>
 Shiraz Hashim <shiraz.linux.kernel@gmail.com> <shiraz.hashim@st.com>
 Shuah Khan <shuah@kernel.org> <shuahkhan@gmail.com>
 Shuah Khan <shuah@kernel.org> <shuah.khan@hp.com>

CREDITS

@@ -1439,6 +1439,10 @@ N: Justin Guyett
 E: jguyett@andrew.cmu.edu
 D: via-rhine net driver hacking
 
+N: Nitin Gupta
+E: ngupta@vflare.org
+D: zsmalloc memory allocator and zram block device driver
+
 N: Danny ter Haar
 E: dth@cistron.nl
 D: /proc/cpuinfo, reboot on panic , kernel pre-patch tester ;)

Documentation/ABI/stable/sysfs-driver-dma-idxd

@@ -22,6 +22,7 @@ Date:           Oct 25, 2019
 KernelVersion:  5.6.0
 Contact:        dmaengine@vger.kernel.org
 Description:    The largest number of work descriptors in a batch.
+                It's not visible when the device does not support batch.
 
 What:           /sys/bus/dsa/devices/dsa<m>/max_work_queues_size
 Date:           Oct 25, 2019
@@ -49,6 +50,8 @@ Description:    The total number of read buffers supported by this device.
 		The read buffers represent resources within the DSA
 		implementation, and these resources are allocated by engines to
 		support operations. See DSA spec v1.2 9.2.4 Total Read Buffers.
+		It's not visible when the device does not support Read Buffer
+		allocation control.
 
 What:           /sys/bus/dsa/devices/dsa<m>/max_transfer_size
 Date:           Oct 25, 2019
@@ -122,6 +125,8 @@ Contact:        dmaengine@vger.kernel.org
 Description:    The maximum number of read buffers that may be in use at
 		one time by operations that access low bandwidth memory in the
 		device. See DSA spec v1.2 9.2.8 GENCFG on Global Read Buffer Limit.
+		It's not visible when the device does not support Read Buffer
+		allocation control.
 
 What:		/sys/bus/dsa/devices/dsa<m>/cmd_status
 Date:		Aug 28, 2020
@@ -205,6 +210,7 @@ KernelVersion:	5.10.0
 Contact:	dmaengine@vger.kernel.org
 Description:	The max batch size for this workqueue. Cannot exceed device
 		max batch size. Configurable parameter.
+		It's not visible when the device does not support batch.
 
 What:		/sys/bus/dsa/devices/wq<m>.<n>/ats_disable
 Date:		Nov 13, 2020
@@ -250,6 +256,8 @@ KernelVersion:	5.17.0
 Contact:	dmaengine@vger.kernel.org
 Description:	Enable the use of global read buffer limit for the group. See DSA
 		spec v1.2 9.2.18 GRPCFG Use Global Read Buffer Limit.
+		It's not visible when the device does not support Read Buffer
+		allocation control.
 
 What:		/sys/bus/dsa/devices/group<m>.<n>/read_buffers_allowed
 Date:		Dec 10, 2021
@@ -258,6 +266,8 @@ Contact:	dmaengine@vger.kernel.org
 Description:	Indicates max number of read buffers that may be in use at one time
 		by all engines in the group. See DSA spec v1.2 9.2.18 GRPCFG Read
 		Buffers Allowed.
+		It's not visible when the device does not support Read Buffer
+		allocation control.
 
 What:		/sys/bus/dsa/devices/group<m>.<n>/read_buffers_reserved
 Date:		Dec 10, 2021
@@ -266,6 +276,8 @@ Contact:	dmaengine@vger.kernel.org
 Description:	Indicates the number of Read Buffers reserved for the use of
 		engines in the group. See DSA spec v1.2 9.2.18 GRPCFG Read Buffers
 		Reserved.
+		It's not visible when the device does not support Read Buffer
+		allocation control.
 
 What:		/sys/bus/dsa/devices/group<m>.<n>/desc_progress_limit
 Date:		Sept 14, 2022

Documentation/ABI/stable/sysfs-driver-speakup

@@ -35,6 +35,15 @@ Description:	This controls cursor delay when using arrow keys. When a
 		characters. Set this to a higher value to adjust for the delay
 		and better synchronisation between cursor position and speech.
 
+What:		/sys/accessibility/speakup/cur_phonetic
+KernelVersion:	6.2
+Contact:	speakup@linux-speakup.org
+Description:	This allows speakup to speak letters phoneticaly when arrowing through
+		a word letter by letter. This doesn't affect the spelling when typing
+		the characters. When cur_phonetic=1, speakup will speak characters
+		phoneticaly when arrowing over a letter. When cur_phonetic=0, speakup
+		will speak letters as normally.
+
 What:		/sys/accessibility/speakup/delimiters
 KernelVersion:	2.6
 Contact:	speakup@linux-speakup.org

Documentation/ABI/testing/configfs-usb-gadget-uvc

@@ -197,7 +197,7 @@ Description:	Specific MJPEG format descriptors
 					read-only
 		bmaControls		this format's data for bmaControls in
 					the streaming header
-		bmInterfaceFlags	specifies interlace information,
+		bmInterlaceFlags	specifies interlace information,
 					read-only
 		bAspectRatioY		the X dimension of the picture aspect
 					ratio, read-only
@@ -253,7 +253,7 @@ Description:	Specific uncompressed format descriptors
 					read-only
 		bmaControls		this format's data for bmaControls in
 					the streaming header
-		bmInterfaceFlags	specifies interlace information,
+		bmInterlaceFlags	specifies interlace information,
 					read-only
 		bAspectRatioY		the X dimension of the picture aspect
 					ratio, read-only

Documentation/ABI/testing/debugfs-dell-wmi-ddv

+What:		/sys/kernel/debug/dell-wmi-ddv-<wmi_device_name>/fan_sensor_information
+Date:		September 2022
+KernelVersion:	6.1
+Contact:	Armin Wolf <W_Armin@gmx.de>
+Description:
+		This file contains the contents of the fan sensor information buffer,
+		which contains fan sensor entries and a terminating character (0xFF).
+
+		Each fan sensor entry consists of three bytes with an unknown meaning,
+		interested people may use this file for reverse-engineering.
+
+What:		/sys/kernel/debug/dell-wmi-ddv-<wmi_device_name>/thermal_sensor_information
+Date:		September 2022
+KernelVersion:	6.1
+Contact:	Armin Wolf <W_Armin@gmx.de>
+Description:
+		This file contains the contents of the thermal sensor information buffer,
+		which contains thermal sensor entries and a terminating character (0xFF).
+
+		Each thermal sensor entry consists of five bytes with an unknown meaning,
+		interested people may use this file for reverse-engineering.

Documentation/ABI/testing/debugfs-driver-habanalabs

@@ -91,6 +91,13 @@ Description:    Enables the root user to set the device to specific state.
                 Valid values are "disable", "enable", "suspend", "resume".
                 User can read this property to see the valid values
 
+What:           /sys/kernel/debug/habanalabs/hl<n>/device_release_watchdog_timeout
+Date:           Oct 2022
+KernelVersion:  6.2
+Contact:        ttayar@habana.ai
+Description:    The watchdog timeout value in seconds for a device relese upon
+                certain error cases, after which the device is reset.
+
 What:           /sys/kernel/debug/habanalabs/hl<n>/dma_size
 Date:           Apr 2021
 KernelVersion:  5.13

Documentation/ABI/testing/debugfs-pktcdvd

-What:           /sys/kernel/debug/pktcdvd/pktcdvd[0-7]
-Date:           Oct. 2006
-KernelVersion:  2.6.20
-Contact:        Thomas Maier <balagi@justmail.de>
-Description:
-
-The pktcdvd module (packet writing driver) creates
-these files in debugfs:
-
-/sys/kernel/debug/pktcdvd/pktcdvd[0-7]/
-
-    ====            ====== ====================================
-    info            0444   Lots of driver statistics and infos.
-    ====            ====== ====================================
-
-Example::
-
-    cat /sys/kernel/debug/pktcdvd/pktcdvd0/info

Documentation/ABI/testing/sysfs-block-zram

@@ -137,3 +137,17 @@ Description:
 		The writeback_limit file is read-write and specifies the maximum
 		amount of writeback ZRAM can do. The limit could be changed
 		in run time.
+
+What:		/sys/block/zram<id>/recomp_algorithm
+Date:		November 2022
+Contact:	Sergey Senozhatsky <senozhatsky@chromium.org>
+Description:
+		The recomp_algorithm file is read-write and allows to set
+		or show secondary compression algorithms.
+
+What:		/sys/block/zram<id>/recompress
+Date:		November 2022
+Contact:	Sergey Senozhatsky <senozhatsky@chromium.org>
+Description:
+		The recompress file is write-only and triggers re-compression
+		with secondary compression algorithms.

Documentation/ABI/testing/sysfs-bus-coreboot

+What:		/sys/bus/coreboot
+Date:		August 2022
+Contact:	Jack Rosenthal <jrosenth@chromium.org>
+Description:
+		The coreboot bus provides a variety of virtual devices used to
+		access data structures created by the Coreboot BIOS.
+
+What:		/sys/bus/coreboot/devices/cbmem-<id>
+Date:		August 2022
+Contact:	Jack Rosenthal <jrosenth@chromium.org>
+Description:
+		CBMEM is a downwards-growing memory region created by Coreboot,
+		and contains tagged data structures to be shared with payloads
+		in the boot process and the OS.  Each CBMEM entry is given a
+		directory in /sys/bus/coreboot/devices based on its id.
+		A list of ids known to Coreboot can be found in the coreboot
+		source tree at
+		``src/commonlib/bsd/include/commonlib/bsd/cbmem_id.h``.
+
+What:		/sys/bus/coreboot/devices/cbmem-<id>/address
+Date:		August 2022
+Contact:	Jack Rosenthal <jrosenth@chromium.org>
+Description:
+		This is the pyhsical memory address that the CBMEM entry's data
+		begins at, in hexadecimal (e.g., ``0x76ffe000``).
+
+What:		/sys/bus/coreboot/devices/cbmem-<id>/size
+Date:		August 2022
+Contact:	Jack Rosenthal <jrosenth@chromium.org>
+Description:
+		This is the size of the CBMEM entry's data, in hexadecimal
+		(e.g., ``0x1234``).
+
+What:		/sys/bus/coreboot/devices/cbmem-<id>/mem
+Date:		August 2022
+Contact:	Jack Rosenthal <jrosenth@chromium.org>
+Description:
+		A file exposing read/write access to the entry's data.  Note
+		that this file does not support mmap(), as coreboot
+		does not guarantee that the data will be page-aligned.
+
+		The mode of this file is 0600.  While there shouldn't be
+		anything security-sensitive contained in CBMEM, read access
+		requires root privileges given this is exposing a small subset
+		of physical memory.

Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130

+What:		/sys/bus/iio/devices/iio:deviceX/in_voltage-voltage_filter_mode_available
+KernelVersion:  6.2
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Reading returns a list with the possible filter modes.
+
+		  * "sinc4"       - Sinc 4. Excellent noise performance. Long
+                    1st conversion time. No natural 50/60Hz rejection.
+
+		  * "sinc4+sinc1" - Sinc4 + averaging by 8. Low 1st conversion
+		    time.
+
+		  * "sinc3"	      - Sinc3. Moderate 1st conversion time.
+		    Good noise performance.
+
+		  * "sinc3+rej60" - Sinc3 + 60Hz rejection. At a sampling
+		    frequency of 50Hz, achieves simultaneous 50Hz and 60Hz
+		    rejection.
+
+		  * "sinc3+sinc1" - Sinc3 + averaging by 8. Low 1st conversion
+		    time. Best used with a sampling frequency of at least
+		    216.19Hz.
+
+		  * "sinc3+pf1"   - Sinc3 + Post Filter 1. 53dB rejection @
+		    50Hz, 58dB rejection @ 60Hz.
+
+		  * "sinc3+pf2"   - Sinc3 + Post Filter 2. 70dB rejection @
+		    50Hz, 70dB rejection @ 60Hz.
+
+		  * "sinc3+pf3"   - Sinc3 + Post Filter 3. 99dB rejection @
+		    50Hz, 103dB rejection @ 60Hz.
+
+		  * "sinc3+pf4"   - Sinc3 + Post Filter 4. 103dB rejection @
+		    50Hz, 109dB rejection @ 60Hz.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY-voltageZ_filter_mode
+KernelVersion:  6.2
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Set the filter mode of the differential channel. When the filter
+		mode changes, the in_voltageY-voltageZ_sampling_frequency and
+		in_voltageY-voltageZ_sampling_frequency_available attributes
+		might also change to accommodate the new filter mode.
+		If the current sampling frequency is out of range for the new
+		filter mode, the sampling frequency will be changed to the
+		closest valid one.

Documentation/ABI/testing/sysfs-bus-iio-adc-max11410

+What:		/sys/bus/iio/devices/iio:deviceX/in_voltage_filterY_notch_en
+Date:		September 2022
+KernelVersion:  6.0
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Enable or disable a notch filter.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltage_filterY_notch_center
+Date:		September 2022
+KernelVersion:  6.0
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Center frequency of the notch filter in Hz.

Documentation/ABI/testing/sysfs-bus-nvdimm

@@ -41,3 +41,17 @@ KernelVersion:  5.18
 Contact:        Kajol Jain <kjain@linux.ibm.com>
 Description:	(RO) This sysfs file exposes the cpumask which is designated to
 		to retrieve nvdimm pmu event counter data.
+
+What:		/sys/bus/nd/devices/nmemX/cxl/id
+Date:		November 2022
+KernelVersion:	6.2
+Contact:	Dave Jiang <dave.jiang@intel.com>
+Description:	(RO) Show the id (serial) of the device. This is CXL specific.
+
+What:		/sys/bus/nd/devices/nmemX/cxl/provider
+Date:		November 2022
+KernelVersion:	6.2
+Contact:	Dave Jiang <dave.jiang@intel.com>
+Description:	(RO) Shows the CXL bridge device that ties to a CXL memory device
+		to this NVDIMM device. I.e. the parent of the device returned is
+		a /sys/bus/cxl/devices/memX instance.

Documentation/ABI/testing/sysfs-bus-pci

@@ -407,6 +407,16 @@ Description:
 	        file contains a '1' if the memory has been published for
 		use outside the driver that owns the device.
 
+What:		/sys/bus/pci/devices/.../p2pmem/allocate
+Date:		August 2022
+Contact:	Logan Gunthorpe <logang@deltatee.com>
+Description:
+		This file allows mapping p2pmem into userspace. For each
+		mmap() call on this file, the kernel will allocate a chunk
+		of Peer-to-Peer memory for use in Peer-to-Peer transactions.
+		This memory can be used in O_DIRECT calls to NVMe backed
+		files for Peer-to-Peer copies.
+
 What:		/sys/bus/pci/devices/.../link/clkpm
 		/sys/bus/pci/devices/.../link/l0s_aspm
 		/sys/bus/pci/devices/.../link/l1_aspm

Documentation/ABI/testing/sysfs-bus-spi-devices-spi-nor

@@ -5,6 +5,9 @@ Contact:	linux-mtd@lists.infradead.org
 Description:	(RO) The JEDEC ID of the SPI NOR flash as reported by the
 		flash device.
 
+		The attribute is not present if the flash doesn't support
+		the "Read JEDEC ID" command (9Fh). This is the case for
+		non-JEDEC compliant flashes.
 
 What:		/sys/bus/spi/devices/.../spi-nor/manufacturer
 Date:		April 2021
@@ -12,6 +15,9 @@ KernelVersion:	5.14
 Contact:	linux-mtd@lists.infradead.org
 Description:	(RO) Manufacturer of the SPI NOR flash.
 
+		The attribute is not present if the flash device isn't
+		known to the kernel and is only probed by its SFDP
+		tables.
 
 What:		/sys/bus/spi/devices/.../spi-nor/partname
 Date:		April 2021

Documentation/ABI/testing/sysfs-bus-usb

@@ -264,6 +264,17 @@ Description:
 		attached to the port will not be detected, initialized,
 		or enumerated.
 
+What:		/sys/bus/usb/devices/.../<hub_interface>/port<X>/early_stop
+Date:		Sep 2022
+Contact:	Ray Chi <raychi@google.com>
+Description:
+		Some USB hosts have some watchdog mechanisms so that the device
+		may enter ramdump if it takes a long time during port initialization.
+		This attribute allows each port just has two attempts so that the
+		port initialization will be failed quickly. In addition, if a port
+		which is marked with early_stop has failed to initialize, it will ignore
+		all future connections until this attribute is clear.
+
 What:		/sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 Date:		May 2013
 Contact:	Mathias Nyman <mathias.nyman@linux.intel.com>

Documentation/ABI/testing/sysfs-class-bdi

@@ -44,6 +44,21 @@ Description:
 
 	(read-write)
 
+What:		/sys/class/bdi/<bdi>/min_ratio_fine
+Date:		November 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Under normal circumstances each device is given a part of the
+	total write-back cache that relates to its current average
+	writeout speed in relation to the other devices.
+
+	The 'min_ratio_fine' parameter allows assigning a minimum reserve
+	of the write-back cache to a particular device. The value is
+	expressed as part of 1 million. For example, this is useful for
+	providing a minimum QoS.
+
+	(read-write)
+
 What:		/sys/class/bdi/<bdi>/max_ratio
 Date:		January 2008
 Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
@@ -55,6 +70,59 @@ Description:
 	mount that is prone to get stuck, or a FUSE mount which cannot
 	be trusted to play fair.
 
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/max_ratio_fine
+Date:		November 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Allows limiting a particular device to use not more than the
+	given value of the write-back cache.  The value is given as part
+	of 1 million. This is useful in situations where we want to avoid
+	one device taking all or most of the write-back cache.  For example
+	in case of an NFS mount that is prone to get stuck, or a FUSE mount
+	which cannot be trusted to play fair.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/min_bytes
+Date:		October 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Under normal circumstances each device is given a part of the
+	total write-back cache that relates to its current average
+	writeout speed in relation to the other devices.
+
+	The 'min_bytes' parameter allows assigning a minimum
+	percentage of the write-back cache to a particular device
+	expressed in bytes.
+	For example, this is useful for providing a minimum QoS.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/max_bytes
+Date:		October 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Allows limiting a particular device to use not more than the
+	given 'max_bytes' of the write-back cache.  This is useful in
+	situations where we want to avoid one device taking all or
+	most of the write-back cache.  For example in case of an NFS
+	mount that is prone to get stuck, a FUSE mount which cannot be
+	trusted to play fair, or a nbd device.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/strict_limit
+Date:		October 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Forces per-BDI checks for the share of given device in the write-back
+	cache even before the global background dirty limit is reached. This
+	is useful in situations where the global limit is much higher than
+	affordable for given relatively slow (or untrusted) device. Turning
+	strictlimit on has no visible effect if max_ratio is equal to 100%.
+
 	(read-write)
 What:		/sys/class/bdi/<bdi>/stable_pages_required
 Date:		January 2008

Documentation/ABI/testing/sysfs-class-pktcdvd

-sysfs interface
----------------
-The pktcdvd module (packet writing driver) creates the following files in the
-sysfs: (<devid> is in the format major:minor)
-
-What:		/sys/class/pktcdvd/add
-What:		/sys/class/pktcdvd/remove
-What:		/sys/class/pktcdvd/device_map
-Date:		Oct. 2006
-KernelVersion:	2.6.20
-Contact:	Thomas Maier <balagi@justmail.de>
-Description:
-
-		==========	==============================================
-		add		(WO) Write a block device id (major:minor) to
-				create a new pktcdvd device and map it to the
-				block device.
-
-		remove		(WO) Write the pktcdvd device id (major:minor)
-				to remove the pktcdvd device.
-
-		device_map	(RO) Shows the device mapping in format:
-				pktcdvd[0-7] <pktdevid> <blkdevid>
-		==========	==============================================
-
-
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/dev
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/uevent
-Date:		Oct. 2006
-KernelVersion:	2.6.20
-Contact:	Thomas Maier <balagi@justmail.de>
-Description:
-		dev:	(RO) Device id
-
-		uevent:	(WO) To send a uevent
-
-
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
-Date:		Oct. 2006
-KernelVersion:	2.6.20
-Contact:	Thomas Maier <balagi@justmail.de>
-Description:
-		packets_started:	(RO) Number of started packets.
-
-		packets_finished:	(RO) Number of finished packets.
-
-		kb_written:		(RO) kBytes written.
-
-		kb_read:		(RO) kBytes read.
-
-		kb_read_gather:		(RO) kBytes read to fill write packets.
-
-		reset:			(WO) Write any value to it to reset
-					pktcdvd device statistic values, like
-					bytes read/written.
-
-
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
-What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
-Date:		Oct. 2006
-KernelVersion:	2.6.20
-Contact:	Thomas Maier <balagi@justmail.de>
-Description:
-		==============	================================================
-		size		(RO) Contains the size of the bio write queue.
-
-		congestion_off	(RW) If bio write queue size is below this mark,
-				accept new bio requests from the block layer.
-
-		congestion_on	(RW) If bio write queue size is higher as this
-				mark, do no longer accept bio write requests
-				from the block layer and wait till the pktcdvd
-				device has processed enough bio's so that bio
-				write queue size is below congestion off mark.
-				A value of <= 0 disables congestion control.
-		==============	================================================
-
-
-Example:
---------
-To use the pktcdvd sysfs interface directly, you can do::
-
-    # create a new pktcdvd device mapped to /dev/hdc
-    echo "22:0" >/sys/class/pktcdvd/add
-    cat /sys/class/pktcdvd/device_map
-    # assuming device pktcdvd0 was created, look at stat's
-    cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
-    # print the device id of the mapped block device
-    fgrep pktcdvd0 /sys/class/pktcdvd/device_map
-    # remove device, using pktcdvd0 device id   253:0
-    echo "253:0" >/sys/class/pktcdvd/remove

Documentation/ABI/testing/sysfs-devices-mapping

 What:           /sys/devices/uncore_iio_x/dieX
 Date:           February 2020
-Contact:        Roman Sudarikov <roman.sudarikov@linux.intel.com>
+Contact:        Alexander Antonov <alexander.antonov@linux.intel.com>
 Description:
                 Each IIO stack (PCIe root port) has its own IIO PMON block, so
                 each dieX file (where X is die number) holds "Segment:Root Bus"
@@ -32,3 +32,31 @@ Description:
 		    IIO PMU 0 on die 1 belongs to PCI RP on bus 0x40, domain 0x0000
 		    IIO PMU 0 on die 2 belongs to PCI RP on bus 0x80, domain 0x0000
 		    IIO PMU 0 on die 3 belongs to PCI RP on bus 0xc0, domain 0x0000
+
+What:           /sys/devices/uncore_upi_x/dieX
+Date:           March 2022
+Contact:        Alexander Antonov <alexander.antonov@linux.intel.com>
+Description:
+                Each /sys/devices/uncore_upi_X/dieY file holds "upi_Z,die_W"
+                value that means UPI link number X on die Y is connected to UPI
+                link Z on die W and this link between sockets can be monitored
+                by UPI PMON block.
+                For example, 4-die Sapphire Rapids platform has the following
+                UPI 0 topology::
+
+		    # tail /sys/devices/uncore_upi_0/die*
+		    ==> /sys/devices/uncore_upi_0/die0 <==
+		    upi_1,die_1
+		    ==> /sys/devices/uncore_upi_0/die1 <==
+		    upi_0,die_3
+		    ==> /sys/devices/uncore_upi_0/die2 <==
+		    upi_1,die_3
+		    ==> /sys/devices/uncore_upi_0/die3 <==
+		    upi_0,die_1
+
+                Which means::
+
+		    UPI link 0 on die 0 is connected to UPI link 1 on die 1
+		    UPI link 0 on die 1 is connected to UPI link 0 on die 3
+		    UPI link 0 on die 2 is connected to UPI link 1 on die 3
+		    UPI link 0 on die 3 is connected to UPI link 0 on die 1
\ No newline at end of file

Documentation/ABI/testing/sysfs-driver-intel_sdsi

@@ -4,21 +4,21 @@ KernelVersion:	5.18
 Contact:	"David E. Box" <david.e.box@linux.intel.com>
 Description:
 		This directory contains interface files for accessing Intel
-		Software Defined Silicon (SDSi) features on a CPU. X
-		represents the socket instance (though not the socket ID).
-		The socket ID is determined by reading the registers file
-		and decoding it per the specification.
+		On Demand (formerly Software Defined Silicon or SDSi) features
+		on a CPU. X represents the socket instance (though not the
+		socket ID). The socket ID is determined by reading the
+		registers file and decoding it per the specification.
 
-		Some files communicate with SDSi hardware through a mailbox.
-		Should the operation fail, one of the following error codes
-		may be returned:
+		Some files communicate with On Demand hardware through a
+		mailbox. Should the operation fail, one of the following error
+		codes may be returned:
 
 		==========	=====
 		Error Code	Cause
 		==========	=====
 		EIO		General mailbox failure. Log may indicate cause.
 		EBUSY		Mailbox is owned by another agent.
-		EPERM		SDSI capability is not enabled in hardware.
+		EPERM		On Demand capability is not enabled in hardware.
 		EPROTO		Failure in mailbox protocol detected by driver.
 				See log for details.
 		EOVERFLOW	For provision commands, the size of the data
@@ -54,8 +54,8 @@ KernelVersion:	5.18
 Contact:	"David E. Box" <david.e.box@linux.intel.com>
 Description:
 		(WO) Used to write an Authentication Key Certificate (AKC) to
-		the SDSi NVRAM for the CPU. The AKC is used to authenticate a
-		Capability Activation Payload. Mailbox command.
+		the On Demand NVRAM for the CPU. The AKC is used to authenticate
+		a Capability Activation Payload. Mailbox command.
 
 What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/provision_cap
 Date:		Feb 2022
@@ -63,17 +63,28 @@ KernelVersion:	5.18
 Contact:	"David E. Box" <david.e.box@linux.intel.com>
 Description:
 		(WO) Used to write a Capability Activation Payload (CAP) to the
-		SDSi NVRAM for the CPU. CAPs are used to activate a given CPU
-		feature. A CAP is validated by SDSi hardware using a previously
-		provisioned AKC file. Upon successful authentication, the CPU
-		configuration is updated. A cold reboot is required to fully
-		activate the feature. Mailbox command.
+		On Demand NVRAM for the CPU. CAPs are used to activate a given
+		CPU feature. A CAP is validated by On Demand hardware using a
+		previously provisioned AKC file. Upon successful authentication,
+		the CPU configuration is updated. A cold reboot is required to
+		fully activate the feature. Mailbox command.
+
+What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/meter_certificate
+Date:		Nov 2022
+KernelVersion:	6.2
+Contact:	"David E. Box" <david.e.box@linux.intel.com>
+Description:
+		(RO) Used to read back the current meter certificate for the CPU
+		from Intel On Demand hardware. The meter certificate contains
+		utilization metrics of On Demand enabled features. Mailbox
+		command.
 
 What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/state_certificate
 Date:		Feb 2022
 KernelVersion:	5.18
 Contact:	"David E. Box" <david.e.box@linux.intel.com>
 Description:
-		(RO) Used to read back the current State Certificate for the CPU
-		from SDSi hardware. The State Certificate contains information
-		about the current licenses on the CPU. Mailbox command.
+		(RO) Used to read back the current state certificate for the CPU
+		from On Demand hardware. The state certificate contains
+		information about the current licenses on the CPU. Mailbox
+		command.

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -99,6 +99,12 @@ Description:	Controls the issue rate of discard commands that consist of small
 		checkpoint is triggered, and issued during the checkpoint.
 		By default, it is disabled with 0.
 
+What:		/sys/fs/f2fs/<disk>/max_ordered_discard
+Date:		October 2022
+Contact:	"Yangtao Li" <frank.li@vivo.com>
+Description:	Controls the maximum ordered discard, the unit size is one block(4KB).
+		Set it to 16 by default.
+
 What:		/sys/fs/f2fs/<disk>/max_discard_request
 Date:		December 2021
 Contact:	"Konstantin Vyshetsky" <vkon@google.com>
@@ -132,7 +138,8 @@ Contact:	"Chao Yu" <yuchao0@huawei.com>
 Description:	Controls discard granularity of inner discard thread. Inner thread
 		will not issue discards with size that is smaller than granularity.
 		The unit size is one block(4KB), now only support configuring
-		in range of [1, 512]. Default value is 4(=16KB).
+		in range of [1, 512]. Default value is 16.
+		For small devices, default value is 1.
 
 What:		/sys/fs/f2fs/<disk>/umount_discard_timeout
 Date:		January 2019
@@ -235,7 +242,7 @@ Description:	Shows total written kbytes issued to disk.
 What:		/sys/fs/f2fs/<disk>/features
 Date:		July 2017
 Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
-Description:	<deprecated: should use /sys/fs/f2fs/<disk>/feature_list/
+Description:	<deprecated: should use /sys/fs/f2fs/<disk>/feature_list/>
 		Shows all enabled features in current device.
 		Supported features:
 		encryption, blkzoned, extra_attr, projquota, inode_checksum,
@@ -592,10 +599,10 @@ Description:	With "mode=fragment:block" mount options, we can scatter block allo
 		in the length of 1..<max_fragment_hole> by turns. This value can be set
 		between 1..512 and the default value is 4.
 
-What:		/sys/fs/f2fs/<disk>/gc_urgent_high_remaining
-Date:		December 2021
-Contact:	"Daeho Jeong" <daehojeong@google.com>
-Description:	You can set the trial count limit for GC urgent high mode with this value.
+What:		/sys/fs/f2fs/<disk>/gc_remaining_trials
+Date:		October 2022
+Contact:	"Yangtao Li" <frank.li@vivo.com>
+Description:	You can set the trial count limit for GC urgent and idle mode with this value.
 		If GC thread gets to the limit, the mode will turn back to GC normal mode.
 		By default, the value is zero, which means there is no limit like before.
 
@@ -634,3 +641,31 @@ Date:		July 2022
 Contact:	"Daeho Jeong" <daehojeong@google.com>
 Description:	Show the accumulated total revoked atomic write block count after boot.
 		If you write "0" here, you can initialize to "0".
+
+What:		/sys/fs/f2fs/<disk>/gc_mode
+Date:		October 2022
+Contact:	"Yangtao Li" <frank.li@vivo.com>
+Description:	Show the current gc_mode as a string.
+		This is a read-only entry.
+
+What:		/sys/fs/f2fs/<disk>/discard_urgent_util
+Date:		November 2022
+Contact:	"Yangtao Li" <frank.li@vivo.com>
+Description:	When space utilization exceeds this, do background DISCARD aggressively.
+		Does DISCARD forcibly in a period of given min_discard_issue_time when the number
+		of discards is not 0 and set discard granularity to 1.
+		Default: 80
+
+What:		/sys/fs/f2fs/<disk>/hot_data_age_threshold
+Date:		November 2022
+Contact:	"Ping Xiong" <xiongping1@xiaomi.com>
+Description:	When DATA SEPARATION is on, it controls the age threshold to indicate
+		the data blocks as hot. By default it was initialized as 262144 blocks
+		(equals to 1GB).
+
+What:		/sys/fs/f2fs/<disk>/warm_data_age_threshold
+Date:		November 2022
+Contact:	"Ping Xiong" <xiongping1@xiaomi.com>
+Description:	When DATA SEPARATION is on, it controls the age threshold to indicate
+		the data blocks as warm. By default it was initialized as 2621440 blocks
+		(equals to 10GB).

Documentation/ABI/testing/sysfs-kernel-cpu_byteorder

+What:		/sys/kernel/cpu_byteorder
+Date:		February 2023
+KernelVersion:	6.2
+Contact:	Thomas Weißschuh <linux@weissschuh.net>
+Description:
+		The endianness of the running kernel.
+
+		Access: Read
+
+		Valid values:
+			"little", "big"
+Users:		util-linux

Documentation/ABI/testing/sysfs-kernel-mm-damon

@@ -27,6 +27,10 @@ Description:	Writing 'on' or 'off' to this file makes the kdamond starts or
 		makes the kdamond reads the user inputs in the sysfs files
 		except 'state' again.  Writing 'update_schemes_stats' to the
 		file updates contents of schemes stats files of the kdamond.
+		Writing 'update_schemes_tried_regions' to the file updates
+		contents of 'tried_regions' directory of every scheme directory
+		of this kdamond.  Writing 'clear_schemes_tried_regions' to the
+		file removes contents of the 'tried_regions' directory.
 
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/pid
 Date:		Mar 2022
@@ -283,3 +287,31 @@ Date:		Mar 2022
 Contact:	SeongJae Park <sj@kernel.org>
 Description:	Reading this file returns the number of the exceed events of
 		the scheme's quotas.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/tried_regions/<R>/start
+Date:		Oct 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the start address of a memory region
+		that corresponding DAMON-based Operation Scheme's action has
+		tried to be applied.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/tried_regions/<R>/end
+Date:		Oct 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the end address of a memory region
+		that corresponding DAMON-based Operation Scheme's action has
+		tried to be applied.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/tried_regions/<R>/nr_accesses
+Date:		Oct 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the 'nr_accesses' of a memory region
+		that corresponding DAMON-based Operation Scheme's action has
+		tried to be applied.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/tried_regions/<R>/age
+Date:		Oct 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the 'age' of a memory region that
+		corresponding DAMON-based Operation Scheme's action has tried
+		to be applied.

Documentation/ABI/testing/sysfs-kernel-oops_count

+What:		/sys/kernel/oops_count
+Date:		November 2022
+KernelVersion:	6.2.0
+Contact:	Linux Kernel Hardening List <linux-hardening@vger.kernel.org>
+Description:
+		Shows how many times the system has Oopsed since last boot.

Documentation/ABI/testing/sysfs-kernel-warn_count

+What:		/sys/kernel/warn_count
+Date:		November 2022
+KernelVersion:	6.2.0
+Contact:	Linux Kernel Hardening List <linux-hardening@vger.kernel.org>
+Description:
+		Shows how many times the system has Warned since last boot.

Documentation/ABI/testing/sysfs-platform-dell-wmi-ddv

+What:		/sys/class/power_supply/<battery_name>/eppid
+Date:		September 2022
+KernelVersion:	6.1
+Contact:	Armin Wolf <W_Armin@gmx.de>
+Description:
+		Reports the Dell ePPID (electronic Dell Piece Part Identification)
+		of the ACPI battery.

Documentation/ABI/testing/sysfs-platform-intel-ifs

 What:		/sys/devices/virtual/misc/intel_ifs_<N>/run_test
-Date:		April 21 2022
-KernelVersion:	5.19
+Date:		Nov 16 2022
+KernelVersion:	6.2
 Contact:	"Jithu Joseph" <jithu.joseph@intel.com>
 Description:	Write <cpu#> to trigger IFS test for one online core.
 		Note that the test is per core. The cpu# can be
 		for any thread on the core. Running on one thread
 		completes the test for the core containing that thread.
 		Example: to test the core containing cpu5: echo 5 >
-		/sys/devices/platform/intel_ifs.<N>/run_test
+		/sys/devices/virtual/misc/intel_ifs_<N>/run_test
 
 What:		/sys/devices/virtual/misc/intel_ifs_<N>/status
-Date:		April 21 2022
-KernelVersion:	5.19
+Date:		Nov 16 2022
+KernelVersion:	6.2
 Contact:	"Jithu Joseph" <jithu.joseph@intel.com>
 Description:	The status of the last test. It can be one of "pass", "fail"
 		or "untested".
 
 What:		/sys/devices/virtual/misc/intel_ifs_<N>/details
-Date:		April 21 2022
-KernelVersion:	5.19
+Date:		Nov 16 2022
+KernelVersion:	6.2
 Contact:	"Jithu Joseph" <jithu.joseph@intel.com>
 Description:	Additional information regarding the last test. The details file reports
 		the hex value of the SCAN_STATUS MSR. Note that the error_code field
 		may contain driver defined software code not defined in the Intel SDM.
 
 What:		/sys/devices/virtual/misc/intel_ifs_<N>/image_version
-Date:		April 21 2022
-KernelVersion:	5.19
+Date:		Nov 16 2022
+KernelVersion:	6.2
 Contact:	"Jithu Joseph" <jithu.joseph@intel.com>
 Description:	Version (hexadecimal) of loaded IFS binary image. If no scan image
 		is loaded reports "none".
 
-What:		/sys/devices/virtual/misc/intel_ifs_<N>/reload
-Date:		April 21 2022
-KernelVersion:	5.19
+What:		/sys/devices/virtual/misc/intel_ifs_<N>/current_batch
+Date:		Nov 16 2022
+KernelVersion:	6.2
 Contact:	"Jithu Joseph" <jithu.joseph@intel.com>
-Description:	Write "1" (or "y" or "Y") to reload the IFS image from
-		/lib/firmware/intel/ifs/ff-mm-ss.scan.
+Description:	Write a number less than or equal to 0xff to load an IFS test image.
+		The number written treated as the 2 digit suffix in the following file name:
+		/lib/firmware/intel/ifs_<N>/ff-mm-ss-02x.scan
+		Reading the file will provide the suffix of the currently loaded IFS test image.

Documentation/Makefile

@@ -95,6 +95,15 @@ htmldocs:
 	@$(srctree)/scripts/sphinx-pre-install --version-check
 	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var)))
 
+texinfodocs:
+	@$(srctree)/scripts/sphinx-pre-install --version-check
+	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,texinfo,$(var),texinfo,$(var)))
+
+# Note: the 'info' Make target is generated by sphinx itself when
+# running the texinfodocs target define above.
+infodocs: texinfodocs
+	$(MAKE) -C $(BUILDDIR)/texinfo info
+
 linkcheckdocs:
 	@$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var)))
 
@@ -143,6 +152,8 @@ cleandocs:
 dochelp:
 	@echo  ' Linux kernel internal documentation in different formats from ReST:'
 	@echo  '  htmldocs        - HTML'
+	@echo  '  texinfodocs     - Texinfo'
+	@echo  '  infodocs        - Info'
 	@echo  '  latexdocs       - LaTeX'
 	@echo  '  pdfdocs         - PDF'
 	@echo  '  epubdocs        - EPUB'

Documentation/PCI/msi-howto.rst

@@ -285,3 +285,13 @@ to bridges between the PCI root and the device, MSIs are disabled.
 It is also worth checking the device driver to see whether it supports MSIs.
 For example, it may contain calls to pci_alloc_irq_vectors() with the
 PCI_IRQ_MSI or PCI_IRQ_MSIX flags.
+
+
+List of device drivers MSI(-X) APIs
+===================================
+
+The PCI/MSI subystem has a dedicated C file for its exported device driver
+APIs — `drivers/pci/msi/api.c`. The following functions are exported:
+
+.. kernel-doc:: drivers/pci/msi/api.c
+   :export:

Documentation/PCI/pci-error-recovery.rst

@@ -83,6 +83,7 @@ This structure has the form::
 		int (*mmio_enabled)(struct pci_dev *dev);
 		int (*slot_reset)(struct pci_dev *dev);
 		void (*resume)(struct pci_dev *dev);
+		void (*cor_error_detected)(struct pci_dev *dev);
 	};
 
 The possible channel states are::
@@ -422,5 +423,11 @@ That is, the recovery API only requires that:
    - drivers/net/cxgb3
    - drivers/net/s2io.c
 
+   The cor_error_detected() callback is invoked in handle_error_source() when
+   the error severity is "correctable". The callback is optional and allows
+   additional logging to be done if desired. See example:
+
+   - drivers/cxl/pci.c
+
 The End
 -------

Documentation/RCU/Design/Requirements/Requirements.rst

@@ -1858,7 +1858,7 @@ unloaded. After a given module has been unloaded, any attempt to call
 one of its functions results in a segmentation fault. The module-unload
 functions must therefore cancel any delayed calls to loadable-module
 functions, for example, any outstanding mod_timer() must be dealt
-with via del_timer_sync() or similar.
+with via timer_shutdown_sync() or similar.
 
 Unfortunately, there is no way to cancel an RCU callback; once you
 invoke call_rcu(), the callback function is eventually going to be

Documentation/RCU/arrayRCU.rst

-.. _array_rcu_doc:
-
-Using RCU to Protect Read-Mostly Arrays
-=======================================
-
-Although RCU is more commonly used to protect linked lists, it can
-also be used to protect arrays.  Three situations are as follows:
-
-1.  :ref:`Hash Tables <hash_tables>`
-
-2.  :ref:`Static Arrays <static_arrays>`
-
-3.  :ref:`Resizable Arrays <resizable_arrays>`
-
-Each of these three situations involves an RCU-protected pointer to an
-array that is separately indexed.  It might be tempting to consider use
-of RCU to instead protect the index into an array, however, this use
-case is **not** supported.  The problem with RCU-protected indexes into
-arrays is that compilers can play way too many optimization games with
-integers, which means that the rules governing handling of these indexes
-are far more trouble than they are worth.  If RCU-protected indexes into
-arrays prove to be particularly valuable (which they have not thus far),
-explicit cooperation from the compiler will be required to permit them
-to be safely used.
-
-That aside, each of the three RCU-protected pointer situations are
-described in the following sections.
-
-.. _hash_tables:
-
-Situation 1: Hash Tables
-------------------------
-
-Hash tables are often implemented as an array, where each array entry
-has a linked-list hash chain.  Each hash chain can be protected by RCU
-as described in listRCU.rst.  This approach also applies to other
-array-of-list situations, such as radix trees.
-
-.. _static_arrays:
-
-Situation 2: Static Arrays
---------------------------
-
-Static arrays, where the data (rather than a pointer to the data) is
-located in each array element, and where the array is never resized,
-have not been used with RCU.  Rik van Riel recommends using seqlock in
-this situation, which would also have minimal read-side overhead as long
-as updates are rare.
-
-Quick Quiz:
-		Why is it so important that updates be rare when using seqlock?
-
-:ref:`Answer to Quick Quiz <answer_quick_quiz_seqlock>`
-
-.. _resizable_arrays:
-
-Situation 3: Resizable Arrays
-------------------------------
-
-Use of RCU for resizable arrays is demonstrated by the grow_ary()
-function formerly used by the System V IPC code.  The array is used
-to map from semaphore, message-queue, and shared-memory IDs to the data
-structure that represents the corresponding IPC construct.  The grow_ary()
-function does not acquire any locks; instead its caller must hold the
-ids->sem semaphore.
-
-The grow_ary() function, shown below, does some limit checks, allocates a
-new ipc_id_ary, copies the old to the new portion of the new, initializes
-the remainder of the new, updates the ids->entries pointer to point to
-the new array, and invokes ipc_rcu_putref() to free up the old array.
-Note that rcu_assign_pointer() is used to update the ids->entries pointer,
-which includes any memory barriers required on whatever architecture
-you are running on::
-
-	static int grow_ary(struct ipc_ids* ids, int newsize)
-	{
-		struct ipc_id_ary* new;
-		struct ipc_id_ary* old;
-		int i;
-		int size = ids->entries->size;
-
-		if(newsize > IPCMNI)
-			newsize = IPCMNI;
-		if(newsize <= size)
-			return newsize;
-
-		new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*newsize +
-				    sizeof(struct ipc_id_ary));
-		if(new == NULL)
-			return size;
-		new->size = newsize;
-		memcpy(new->p, ids->entries->p,
-		       sizeof(struct kern_ipc_perm *)*size +
-		       sizeof(struct ipc_id_ary));
-		for(i=size;i<newsize;i++) {
-			new->p[i] = NULL;
-		}
-		old = ids->entries;
-
-		/*
-		 * Use rcu_assign_pointer() to make sure the memcpyed
-		 * contents of the new array are visible before the new
-		 * array becomes visible.
-		 */
-		rcu_assign_pointer(ids->entries, new);
-
-		ipc_rcu_putref(old);
-		return newsize;
-	}
-
-The ipc_rcu_putref() function decrements the array's reference count
-and then, if the reference count has dropped to zero, uses call_rcu()
-to free the array after a grace period has elapsed.
-
-The array is traversed by the ipc_lock() function.  This function
-indexes into the array under the protection of rcu_read_lock(),
-using rcu_dereference() to pick up the pointer to the array so
-that it may later safely be dereferenced -- memory barriers are
-required on the Alpha CPU.  Since the size of the array is stored
-with the array itself, there can be no array-size mismatches, so
-a simple check suffices.  The pointer to the structure corresponding
-to the desired IPC object is placed in "out", with NULL indicating
-a non-existent entry.  After acquiring "out->lock", the "out->deleted"
-flag indicates whether the IPC object is in the process of being
-deleted, and, if not, the pointer is returned::
-
-	struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
-	{
-		struct kern_ipc_perm* out;
-		int lid = id % SEQ_MULTIPLIER;
-		struct ipc_id_ary* entries;
-
-		rcu_read_lock();
-		entries = rcu_dereference(ids->entries);
-		if(lid >= entries->size) {
-			rcu_read_unlock();
-			return NULL;
-		}
-		out = entries->p[lid];
-		if(out == NULL) {
-			rcu_read_unlock();
-			return NULL;
-		}
-		spin_lock(&out->lock);
-
-		/* ipc_rmid() may have already freed the ID while ipc_lock
-		 * was spinning: here verify that the structure is still valid
-		 */
-		if (out->deleted) {
-			spin_unlock(&out->lock);
-			rcu_read_unlock();
-			return NULL;
-		}
-		return out;
-	}
-
-.. _answer_quick_quiz_seqlock:
-
-Answer to Quick Quiz:
-	Why is it so important that updates be rare when using seqlock?
-
-	The reason that it is important that updates be rare when
-	using seqlock is that frequent updates can livelock readers.
-	One way to avoid this problem is to assign a seqlock for
-	each array entry rather than to the entire array.

Documentation/RCU/checklist.rst

@@ -32,8 +32,8 @@ over a rather long period of time, but improvements are always welcome!
 	for lockless updates.  This does result in the mildly
 	counter-intuitive situation where rcu_read_lock() and
 	rcu_read_unlock() are used to protect updates, however, this
-	approach provides the same potential simplifications that garbage
-	collectors do.
+	approach can provide the same simplifications to certain types
+	of lockless algorithms that garbage collectors do.
 
 1.	Does the update code have proper mutual exclusion?
 
@@ -49,12 +49,12 @@ over a rather long period of time, but improvements are always welcome!
 	them -- even x86 allows later loads to be reordered to precede
 	earlier stores), and be prepared to explain why this added
 	complexity is worthwhile.  If you choose #c, be prepared to
-	explain how this single task does not become a major bottleneck on
-	big multiprocessor machines (for example, if the task is updating
-	information relating to itself that other tasks can read, there
-	by definition can be no bottleneck).  Note that the definition
-	of "large" has changed significantly:  Eight CPUs was "large"
-	in the year 2000, but a hundred CPUs was unremarkable in 2017.
+	explain how this single task does not become a major bottleneck
+	on large systems (for example, if the task is updating information
+	relating to itself that other tasks can read, there by definition
+	can be no bottleneck).	Note that the definition of "large" has
+	changed significantly:	Eight CPUs was "large" in the year 2000,
+	but a hundred CPUs was unremarkable in 2017.
 
 2.	Do the RCU read-side critical sections make proper use of
 	rcu_read_lock() and friends?  These primitives are needed
@@ -97,33 +97,38 @@ over a rather long period of time, but improvements are always welcome!
 
 	b.	Proceed as in (a) above, but also maintain per-element
 		locks (that are acquired by both readers and writers)
-		that guard per-element state.  Of course, fields that
-		the readers refrain from accessing can be guarded by
-		some other lock acquired only by updaters, if desired.
+		that guard per-element state.  Fields that the readers
+		refrain from accessing can be guarded by some other lock
+		acquired only by updaters, if desired.
 
-		This works quite well, also.
+		This also works quite well.
 
 	c.	Make updates appear atomic to readers.	For example,
 		pointer updates to properly aligned fields will
 		appear atomic, as will individual atomic primitives.
 		Sequences of operations performed under a lock will *not*
 		appear to be atomic to RCU readers, nor will sequences
-		of multiple atomic primitives.
+		of multiple atomic primitives.	One alternative is to
+		move multiple individual fields to a separate structure,
+		thus solving the multiple-field problem by imposing an
+		additional level of indirection.
 
 		This can work, but is starting to get a bit tricky.
 
-	d.	Carefully order the updates and the reads so that
-		readers see valid data at all phases of the update.
-		This is often more difficult than it sounds, especially
-		given modern CPUs' tendency to reorder memory references.
-		One must usually liberally sprinkle memory barriers
-		(smp_wmb(), smp_rmb(), smp_mb()) through the code,
-		making it difficult to understand and to test.
-
-		It is usually better to group the changing data into
-		a separate structure, so that the change may be made
-		to appear atomic by updating a pointer to reference
-		a new structure containing updated values.
+	d.	Carefully order the updates and the reads so that readers
+		see valid data at all phases of the update.  This is often
+		more difficult than it sounds, especially given modern
+		CPUs' tendency to reorder memory references.  One must
+		usually liberally sprinkle memory-ordering operations
+		through the code, making it difficult to understand and
+		to test.  Where it works, it is better to use things
+		like smp_store_release() and smp_load_acquire(), but in
+		some cases the smp_mb() full memory barrier is required.
+
+		As noted earlier, it is usually better to group the
+		changing data into a separate structure, so that the
+		change may be made to appear atomic by updating a pointer
+		to reference a new structure containing updated values.
 
 4.	Weakly ordered CPUs pose special challenges.  Almost all CPUs
 	are weakly ordered -- even x86 CPUs allow later loads to be
@@ -188,26 +193,29 @@ over a rather long period of time, but improvements are always welcome!
 		when publicizing a pointer to a structure that can
 		be traversed by an RCU read-side critical section.
 
-5.	If call_rcu() or call_srcu() is used, the callback function will
-	be called from softirq context.  In particular, it cannot block.
-	If you need the callback to block, run that code in a workqueue
-	handler scheduled from the callback.  The queue_rcu_work()
-	function does this for you in the case of call_rcu().
+5.	If any of call_rcu(), call_srcu(), call_rcu_tasks(),
+	call_rcu_tasks_rude(), or call_rcu_tasks_trace() is used,
+	the callback function may be invoked from softirq context,
+	and in any case with bottom halves disabled.  In particular,
+	this callback function cannot block.  If you need the callback
+	to block, run that code in a workqueue handler scheduled from
+	the callback.  The queue_rcu_work() function does this for you
+	in the case of call_rcu().
 
 6.	Since synchronize_rcu() can block, it cannot be called
 	from any sort of irq context.  The same rule applies
-	for synchronize_srcu(), synchronize_rcu_expedited(), and
-	synchronize_srcu_expedited().
+	for synchronize_srcu(), synchronize_rcu_expedited(),
+	synchronize_srcu_expedited(), synchronize_rcu_tasks(),
+	synchronize_rcu_tasks_rude(), and synchronize_rcu_tasks_trace().
 
 	The expedited forms of these primitives have the same semantics
-	as the non-expedited forms, but expediting is both expensive and
-	(with the exception of synchronize_srcu_expedited()) unfriendly
-	to real-time workloads.  Use of the expedited primitives should
-	be restricted to rare configuration-change operations that would
-	not normally be undertaken while a real-time workload is running.
-	However, real-time workloads can use rcupdate.rcu_normal kernel
-	boot parameter to completely disable expedited grace periods,
-	though this might have performance implications.
+	as the non-expedited forms, but expediting is more CPU intensive.
+	Use of the expedited primitives should be restricted to rare
+	configuration-change operations that would not normally be
+	undertaken while a real-time workload is running.  Note that
+	IPI-sensitive real-time workloads can use the rcupdate.rcu_normal
+	kernel boot parameter to completely disable expedited grace
+	periods, though this might have performance implications.
 
 	In particular, if you find yourself invoking one of the expedited
 	primitives repeatedly in a loop, please do everyone a favor:
@@ -215,8 +223,9 @@ over a rather long period of time, but improvements are always welcome!
 	a single non-expedited primitive to cover the entire batch.
 	This will very likely be faster than the loop containing the
 	expedited primitive, and will be much much easier on the rest
-	of the system, especially to real-time workloads running on
-	the rest of the system.
+	of the system, especially to real-time workloads running on the
+	rest of the system.  Alternatively, instead use asynchronous
+	primitives such as call_rcu().
 
 7.	As of v4.20, a given kernel implements only one RCU flavor, which
 	is RCU-sched for PREEMPTION=n and RCU-preempt for PREEMPTION=y.
@@ -239,7 +248,8 @@ over a rather long period of time, but improvements are always welcome!
 	the corresponding readers must use rcu_read_lock_trace() and
 	rcu_read_unlock_trace().  If an updater uses call_rcu_tasks_rude()
 	or synchronize_rcu_tasks_rude(), then the corresponding readers
-	must use anything that disables interrupts.
+	must use anything that disables preemption, for example,
+	preempt_disable() and preempt_enable().
 
 	Mixing things up will result in confusion and broken kernels, and
 	has even resulted in an exploitable security issue.  Therefore,
@@ -253,15 +263,16 @@ over a rather long period of time, but improvements are always welcome!
 	that this usage is safe is that readers can use anything that
 	disables BH when updaters use call_rcu() or synchronize_rcu().
 
-8.	Although synchronize_rcu() is slower than is call_rcu(), it
-	usually results in simpler code.  So, unless update performance is
-	critically important, the updaters cannot block, or the latency of
-	synchronize_rcu() is visible from userspace, synchronize_rcu()
-	should be used in preference to call_rcu().  Furthermore,
-	kfree_rcu() usually results in even simpler code than does
-	synchronize_rcu() without synchronize_rcu()'s multi-millisecond
-	latency.  So please take advantage of kfree_rcu()'s "fire and
-	forget" memory-freeing capabilities where it applies.
+8.	Although synchronize_rcu() is slower than is call_rcu(),
+	it usually results in simpler code.  So, unless update
+	performance is critically important, the updaters cannot block,
+	or the latency of synchronize_rcu() is visible from userspace,
+	synchronize_rcu() should be used in preference to call_rcu().
+	Furthermore, kfree_rcu() and kvfree_rcu() usually result
+	in even simpler code than does synchronize_rcu() without
+	synchronize_rcu()'s multi-millisecond latency.	So please take
+	advantage of kfree_rcu()'s and kvfree_rcu()'s "fire and forget"
+	memory-freeing capabilities where it applies.
 
 	An especially important property of the synchronize_rcu()
 	primitive is that it automatically self-limits: if grace periods
@@ -271,8 +282,8 @@ over a rather long period of time, but improvements are always welcome!
 	cases where grace periods are delayed, as failing to do so can
 	result in excessive realtime latencies or even OOM conditions.
 
-	Ways of gaining this self-limiting property when using call_rcu()
-	include:
+	Ways of gaining this self-limiting property when using call_rcu(),
+	kfree_rcu(), or kvfree_rcu() include:
 
 	a.	Keeping a count of the number of data-structure elements
 		used by the RCU-protected data structure, including
@@ -304,18 +315,21 @@ over a rather long period of time, but improvements are always welcome!
 		here is that superuser already has lots of ways to crash
 		the machine.
 
-	d.	Periodically invoke synchronize_rcu(), permitting a limited
-		number of updates per grace period.  Better yet, periodically
-		invoke rcu_barrier() to wait for all outstanding callbacks.
+	d.	Periodically invoke rcu_barrier(), permitting a limited
+		number of updates per grace period.
 
-	The same cautions apply to call_srcu() and kfree_rcu().
+	The same cautions apply to call_srcu(), call_rcu_tasks(),
+	call_rcu_tasks_rude(), and call_rcu_tasks_trace().  This is
+	why there is an srcu_barrier(), rcu_barrier_tasks(),
+	rcu_barrier_tasks_rude(), and rcu_barrier_tasks_rude(),
+	respectively.
 
-	Note that although these primitives do take action to avoid memory
-	exhaustion when any given CPU has too many callbacks, a determined
-	user could still exhaust memory.  This is especially the case
-	if a system with a large number of CPUs has been configured to
-	offload all of its RCU callbacks onto a single CPU, or if the
-	system has relatively little free memory.
+	Note that although these primitives do take action to avoid
+	memory exhaustion when any given CPU has too many callbacks,
+	a determined user or administrator can still exhaust memory.
+	This is especially the case if a system with a large number of
+	CPUs has been configured to offload all of its RCU callbacks onto
+	a single CPU, or if the system has relatively little free memory.
 
 9.	All RCU list-traversal primitives, which include
 	rcu_dereference(), list_for_each_entry_rcu(), and
@@ -344,14 +358,14 @@ over a rather long period of time, but improvements are always welcome!
 	and you don't hold the appropriate update-side lock, you *must*
 	use the "_rcu()" variants of the list macros.  Failing to do so
 	will break Alpha, cause aggressive compilers to generate bad code,
-	and confuse people trying to read your code.
+	and confuse people trying to understand your code.
 
 11.	Any lock acquired by an RCU callback must be acquired elsewhere
-	with softirq disabled, e.g., via spin_lock_irqsave(),
-	spin_lock_bh(), etc.  Failing to disable softirq on a given
-	acquisition of that lock will result in deadlock as soon as
-	the RCU softirq handler happens to run your RCU callback while
-	interrupting that acquisition's critical section.
+	with softirq disabled, e.g., via spin_lock_bh().  Failing to
+	disable softirq on a given acquisition of that lock will result
+	in deadlock as soon as the RCU softirq handler happens to run
+	your RCU callback while interrupting that acquisition's critical
+	section.
 
 12.	RCU callbacks can be and are executed in parallel.  In many cases,
 	the callback code simply wrappers around kfree(), so that this
@@ -372,7 +386,17 @@ over a rather long period of time, but improvements are always welcome!
 	for some  real-time workloads, this is the whole point of using
 	the rcu_nocbs= kernel boot parameter.
 
-13.	Unlike other forms of RCU, it *is* permissible to block in an
+	In addition, do not assume that callbacks queued in a given order
+	will be invoked in that order, even if they all are queued on the
+	same CPU.  Furthermore, do not assume that same-CPU callbacks will
+	be invoked serially.  For example, in recent kernels, CPUs can be
+	switched between offloaded and de-offloaded callback invocation,
+	and while a given CPU is undergoing such a switch, its callbacks
+	might be concurrently invoked by that CPU's softirq handler and
+	that CPU's rcuo kthread.  At such times, that CPU's callbacks
+	might be executed both concurrently and out of order.
+
+13.	Unlike most flavors of RCU, it *is* permissible to block in an
 	SRCU read-side critical section (demarked by srcu_read_lock()
 	and srcu_read_unlock()), hence the "SRCU": "sleepable RCU".
 	Please note that if you don't need to sleep in read-side critical
@@ -412,6 +436,12 @@ over a rather long period of time, but improvements are always welcome!
 	never sends IPIs to other CPUs, so it is easier on
 	real-time workloads than is synchronize_rcu_expedited().
 
+	It is also permissible to sleep in RCU Tasks Trace read-side
+	critical, which are delimited by rcu_read_lock_trace() and
+	rcu_read_unlock_trace().  However, this is a specialized flavor
+	of RCU, and you should not use it without first checking with
+	its current users.  In most cases, you should instead use SRCU.
+
 	Note that rcu_assign_pointer() relates to SRCU just as it does to
 	other forms of RCU, but instead of rcu_dereference() you should
 	use srcu_dereference() in order to avoid lockdep splats.
@@ -442,50 +472,62 @@ over a rather long period of time, but improvements are always welcome!
 	find problems as follows:
 
 	CONFIG_PROVE_LOCKING:
-		check that accesses to RCU-protected data
-		structures are carried out under the proper RCU
-		read-side critical section, while holding the right
-		combination of locks, or whatever other conditions
-		are appropriate.
+		check that accesses to RCU-protected data structures
+		are carried out under the proper RCU read-side critical
+		section, while holding the right combination of locks,
+		or whatever other conditions are appropriate.
 
 	CONFIG_DEBUG_OBJECTS_RCU_HEAD:
-		check that you don't pass the
-		same object to call_rcu() (or friends) before an RCU
-		grace period has elapsed since the last time that you
-		passed that same object to call_rcu() (or friends).
+		check that you don't pass the same object to call_rcu()
+		(or friends) before an RCU grace period has elapsed
+		since the last time that you passed that same object to
+		call_rcu() (or friends).
 
 	__rcu sparse checks:
-		tag the pointer to the RCU-protected data
-		structure with __rcu, and sparse will warn you if you
-		access that pointer without the services of one of the
-		variants of rcu_dereference().
+		tag the pointer to the RCU-protected data structure
+		with __rcu, and sparse will warn you if you access that
+		pointer without the services of one of the variants
+		of rcu_dereference().
 
 	These debugging aids can help you find problems that are
 	otherwise extremely difficult to spot.
 
-17.	If you register a callback using call_rcu() or call_srcu(), and
-	pass in a function defined within a loadable module, then it in
-	necessary to wait for all pending callbacks to be invoked after
-	the last invocation and before unloading that module.  Note that
-	it is absolutely *not* sufficient to wait for a grace period!
-	The current (say) synchronize_rcu() implementation is *not*
-	guaranteed to wait for callbacks registered on other CPUs.
-	Or even on the current CPU if that CPU recently went offline
-	and came back online.
+17.	If you pass a callback function defined within a module to one of
+	call_rcu(), call_srcu(), call_rcu_tasks(), call_rcu_tasks_rude(),
+	or call_rcu_tasks_trace(), then it is necessary to wait for all
+	pending callbacks to be invoked before unloading that module.
+	Note that it is absolutely *not* sufficient to wait for a grace
+	period!  For example, synchronize_rcu() implementation is *not*
+	guaranteed to wait for callbacks registered on other CPUs via
+	call_rcu().  Or even on the current CPU if that CPU recently
+	went offline and came back online.
 
 	You instead need to use one of the barrier functions:
 
 	-	call_rcu() -> rcu_barrier()
 	-	call_srcu() -> srcu_barrier()
+	-	call_rcu_tasks() -> rcu_barrier_tasks()
+	-	call_rcu_tasks_rude() -> rcu_barrier_tasks_rude()
+	-	call_rcu_tasks_trace() -> rcu_barrier_tasks_trace()
 
 	However, these barrier functions are absolutely *not* guaranteed
-	to wait for a grace period.  In fact, if there are no call_rcu()
-	callbacks waiting anywhere in the system, rcu_barrier() is within
-	its rights to return immediately.
-
-	So if you need to wait for both an RCU grace period and for
-	all pre-existing call_rcu() callbacks, you will need to execute
-	both rcu_barrier() and synchronize_rcu(), if necessary, using
-	something like workqueues to execute them concurrently.
+	to wait for a grace period.  For example, if there are no
+	call_rcu() callbacks queued anywhere in the system, rcu_barrier()
+	can and will return immediately.
+
+	So if you need to wait for both a grace period and for all
+	pre-existing callbacks, you will need to invoke both functions,
+	with the pair depending on the flavor of RCU:
+
+	-	Either synchronize_rcu() or synchronize_rcu_expedited(),
+		together with rcu_barrier()
+	-	Either synchronize_srcu() or synchronize_srcu_expedited(),
+		together with and srcu_barrier()
+	-	synchronize_rcu_tasks() and rcu_barrier_tasks()
+	-	synchronize_tasks_rude() and rcu_barrier_tasks_rude()
+	-	synchronize_tasks_trace() and rcu_barrier_tasks_trace()
+
+	If necessary, you can use something like workqueues to execute
+	the requisite pair of functions concurrently.
 
 	See rcubarrier.rst for more information.

Documentation/RCU/index.rst

@@ -9,7 +9,6 @@ RCU concepts
 .. toctree::
    :maxdepth: 3
 
-   arrayRCU
    checklist
    lockdep
    lockdep-splat

Documentation/RCU/listRCU.rst

@@ -3,11 +3,10 @@
 Using RCU to Protect Read-Mostly Linked Lists
 =============================================
 
-One of the best applications of RCU is to protect read-mostly linked lists
-(``struct list_head`` in list.h).  One big advantage of this approach
-is that all of the required memory barriers are included for you in
-the list macros.  This document describes several applications of RCU,
-with the best fits first.
+One of the most common uses of RCU is protecting read-mostly linked lists
+(``struct list_head`` in list.h).  One big advantage of this approach is
+that all of the required memory ordering is provided by the list macros.
+This document describes several list-based RCU use cases.
 
 
 Example 1: Read-mostly list: Deferred Destruction
@@ -35,7 +34,8 @@ The code traversing the list of all processes typically looks like::
 	}
 	rcu_read_unlock();
 
-The simplified code for removing a process from a task list is::
+The simplified and heavily inlined code for removing a process from a
+task list is::
 
 	void release_task(struct task_struct *p)
 	{
@@ -45,39 +45,48 @@ The simplified code for removing a process from a task list is::
 		call_rcu(&p->rcu, delayed_put_task_struct);
 	}
 
-When a process exits, ``release_task()`` calls ``list_del_rcu(&p->tasks)`` under
-``tasklist_lock`` writer lock protection, to remove the task from the list of
-all tasks. The ``tasklist_lock`` prevents concurrent list additions/removals
-from corrupting the list. Readers using ``for_each_process()`` are not protected
-with the ``tasklist_lock``. To prevent readers from noticing changes in the list
-pointers, the ``task_struct`` object is freed only after one or more grace
-periods elapse (with the help of call_rcu()). This deferring of destruction
-ensures that any readers traversing the list will see valid ``p->tasks.next``
-pointers and deletion/freeing can happen in parallel with traversal of the list.
-This pattern is also called an **existence lock**, since RCU pins the object in
-memory until all existing readers finish.
+When a process exits, ``release_task()`` calls ``list_del_rcu(&p->tasks)``
+via __exit_signal() and __unhash_process() under ``tasklist_lock``
+writer lock protection.  The list_del_rcu() invocation removes
+the task from the list of all tasks. The ``tasklist_lock``
+prevents concurrent list additions/removals from corrupting the
+list. Readers using ``for_each_process()`` are not protected with the
+``tasklist_lock``. To prevent readers from noticing changes in the list
+pointers, the ``task_struct`` object is freed only after one or more
+grace periods elapse, with the help of call_rcu(), which is invoked via
+put_task_struct_rcu_user(). This deferring of destruction ensures that
+any readers traversing the list will see valid ``p->tasks.next`` pointers
+and deletion/freeing can happen in parallel with traversal of the list.
+This pattern is also called an **existence lock**, since RCU refrains
+from invoking the delayed_put_task_struct() callback function until
+all existing readers finish, which guarantees that the ``task_struct``
+object in question will remain in existence until after the completion
+of all RCU readers that might possibly have a reference to that object.
 
 
 Example 2: Read-Side Action Taken Outside of Lock: No In-Place Updates
 ----------------------------------------------------------------------
 
-The best applications are cases where, if reader-writer locking were
-used, the read-side lock would be dropped before taking any action
-based on the results of the search.  The most celebrated example is
-the routing table.  Because the routing table is tracking the state of
-equipment outside of the computer, it will at times contain stale data.
-Therefore, once the route has been computed, there is no need to hold
-the routing table static during transmission of the packet.  After all,
-you can hold the routing table static all you want, but that won't keep
-the external Internet from changing, and it is the state of the external
-Internet that really matters.  In addition, routing entries are typically
-added or deleted, rather than being modified in place.
-
-A straightforward example of this use of RCU may be found in the
-system-call auditing support.  For example, a reader-writer locked
+Some reader-writer locking use cases compute a value while holding
+the read-side lock, but continue to use that value after that lock is
+released.  These use cases are often good candidates for conversion
+to RCU.  One prominent example involves network packet routing.
+Because the packet-routing data tracks the state of equipment outside
+of the computer, it will at times contain stale data.  Therefore, once
+the route has been computed, there is no need to hold the routing table
+static during transmission of the packet.  After all, you can hold the
+routing table static all you want, but that won't keep the external
+Internet from changing, and it is the state of the external Internet
+that really matters.  In addition, routing entries are typically added
+or deleted, rather than being modified in place.  This is a rare example
+of the finite speed of light and the non-zero size of atoms actually
+helping make synchronization be lighter weight.
+
+A straightforward example of this type of RCU use case may be found in
+the system-call auditing support.  For example, a reader-writer locked
 implementation of ``audit_filter_task()`` might be as follows::
 
-	static enum audit_state audit_filter_task(struct task_struct *tsk)
+	static enum audit_state audit_filter_task(struct task_struct *tsk, char **key)
 	{
 		struct audit_entry *e;
 		enum audit_state   state;
@@ -86,6 +95,8 @@ implementation of ``audit_filter_task()`` might be as follows::
 		/* Note: audit_filter_mutex held by caller. */
 		list_for_each_entry(e, &audit_tsklist, list) {
 			if (audit_filter_rules(tsk, &e->rule, NULL, &state)) {
+				if (state == AUDIT_STATE_RECORD)
+					*key = kstrdup(e->rule.filterkey, GFP_ATOMIC);
 				read_unlock(&auditsc_lock);
 				return state;
 			}
@@ -101,7 +112,7 @@ you are turning auditing off, it is OK to audit a few extra system calls.
 
 This means that RCU can be easily applied to the read side, as follows::
 
-	static enum audit_state audit_filter_task(struct task_struct *tsk)
+	static enum audit_state audit_filter_task(struct task_struct *tsk, char **key)
 	{
 		struct audit_entry *e;
 		enum audit_state   state;
@@ -110,6 +121,8 @@ This means that RCU can be easily applied to the read side, as follows::
 		/* Note: audit_filter_mutex held by caller. */
 		list_for_each_entry_rcu(e, &audit_tsklist, list) {
 			if (audit_filter_rules(tsk, &e->rule, NULL, &state)) {
+				if (state == AUDIT_STATE_RECORD)
+					*key = kstrdup(e->rule.filterkey, GFP_ATOMIC);
 				rcu_read_unlock();
 				return state;
 			}
@@ -118,13 +131,15 @@ This means that RCU can be easily applied to the read side, as follows::
 		return AUDIT_BUILD_CONTEXT;
 	}
 
-The ``read_lock()`` and ``read_unlock()`` calls have become rcu_read_lock()
-and rcu_read_unlock(), respectively, and the list_for_each_entry() has
-become list_for_each_entry_rcu().  The **_rcu()** list-traversal primitives
-insert the read-side memory barriers that are required on DEC Alpha CPUs.
+The read_lock() and read_unlock() calls have become rcu_read_lock()
+and rcu_read_unlock(), respectively, and the list_for_each_entry()
+has become list_for_each_entry_rcu().  The **_rcu()** list-traversal
+primitives add READ_ONCE() and diagnostic checks for incorrect use
+outside of an RCU read-side critical section.
 
 The changes to the update side are also straightforward. A reader-writer lock
-might be used as follows for deletion and insertion::
+might be used as follows for deletion and insertion in these simplified
+versions of audit_del_rule() and audit_add_rule()::
 
 	static inline int audit_del_rule(struct audit_rule *rule,
 					 struct list_head *list)
@@ -188,16 +203,16 @@ Following are the RCU equivalents for these two functions::
 		return 0;
 	}
 
-Normally, the ``write_lock()`` and ``write_unlock()`` would be replaced by a
+Normally, the write_lock() and write_unlock() would be replaced by a
 spin_lock() and a spin_unlock(). But in this case, all callers hold
 ``audit_filter_mutex``, so no additional locking is required. The
-``auditsc_lock`` can therefore be eliminated, since use of RCU eliminates the
+auditsc_lock can therefore be eliminated, since use of RCU eliminates the
 need for writers to exclude readers.
 
 The list_del(), list_add(), and list_add_tail() primitives have been
 replaced by list_del_rcu(), list_add_rcu(), and list_add_tail_rcu().
-The **_rcu()** list-manipulation primitives add memory barriers that are needed on
-weakly ordered CPUs (most of them!).  The list_del_rcu() primitive omits the
+The **_rcu()** list-manipulation primitives add memory barriers that are
+needed on weakly ordered CPUs.  The list_del_rcu() primitive omits the
 pointer poisoning debug-assist code that would otherwise cause concurrent
 readers to fail spectacularly.
 
@@ -238,7 +253,9 @@ need to be filled in)::
 The RCU version creates a copy, updates the copy, then replaces the old
 entry with the newly updated entry.  This sequence of actions, allowing
 concurrent reads while making a copy to perform an update, is what gives
-RCU (*read-copy update*) its name.  The RCU code is as follows::
+RCU (*read-copy update*) its name.
+
+The RCU version of audit_upd_rule() is as follows::
 
 	static inline int audit_upd_rule(struct audit_rule *rule,
 					 struct list_head *list,
@@ -267,6 +284,9 @@ RCU (*read-copy update*) its name.  The RCU code is as follows::
 Again, this assumes that the caller holds ``audit_filter_mutex``.  Normally, the
 writer lock would become a spinlock in this sort of code.
 
+The update_lsm_rule() does something very similar, for those who would
+prefer to look at real Linux-kernel code.
+
 Another use of this pattern can be found in the openswitch driver's *connection
 tracking table* code in ``ct_limit_set()``.  The table holds connection tracking
 entries and has a limit on the maximum entries.  There is one such table
@@ -281,9 +301,10 @@ Example 4: Eliminating Stale Data
 ---------------------------------
 
 The auditing example above tolerates stale data, as do most algorithms
-that are tracking external state.  Because there is a delay from the
-time the external state changes before Linux becomes aware of the change,
-additional RCU-induced staleness is generally not a problem.
+that are tracking external state.  After all, given there is a delay
+from the time the external state changes before Linux becomes aware
+of the change, and so as noted earlier, a small quantity of additional
+RCU-induced staleness is generally not a problem.
 
 However, there are many examples where stale data cannot be tolerated.
 One example in the Linux kernel is the System V IPC (see the shm_lock()
@@ -302,7 +323,7 @@ Quick Quiz:
 
 If the system-call audit module were to ever need to reject stale data, one way
 to accomplish this would be to add a ``deleted`` flag and a ``lock`` spinlock to the
-audit_entry structure, and modify ``audit_filter_task()`` as follows::
+``audit_entry`` structure, and modify audit_filter_task() as follows::
 
 	static enum audit_state audit_filter_task(struct task_struct *tsk)
 	{
@@ -319,6 +340,8 @@ audit_entry structure, and modify ``audit_filter_task()`` as follows::
 					return AUDIT_BUILD_CONTEXT;
 				}
 				rcu_read_unlock();
+				if (state == AUDIT_STATE_RECORD)
+					*key = kstrdup(e->rule.filterkey, GFP_ATOMIC);
 				return state;
 			}
 		}
@@ -326,12 +349,6 @@ audit_entry structure, and modify ``audit_filter_task()`` as follows::
 		return AUDIT_BUILD_CONTEXT;
 	}
 
-Note that this example assumes that entries are only added and deleted.
-Additional mechanism is required to deal correctly with the update-in-place
-performed by ``audit_upd_rule()``.  For one thing, ``audit_upd_rule()`` would
-need additional memory barriers to ensure that the list_add_rcu() was really
-executed before the list_del_rcu().
-
 The ``audit_del_rule()`` function would need to set the ``deleted`` flag under the
 spinlock as follows::
 
@@ -357,24 +374,32 @@ spinlock as follows::
 
 This too assumes that the caller holds ``audit_filter_mutex``.
 
+Note that this example assumes that entries are only added and deleted.
+Additional mechanism is required to deal correctly with the update-in-place
+performed by audit_upd_rule().  For one thing, audit_upd_rule() would
+need to hold the locks of both the old ``audit_entry`` and its replacement
+while executing the list_replace_rcu().
+
 
 Example 5: Skipping Stale Objects
 ---------------------------------
 
-For some usecases, reader performance can be improved by skipping stale objects
-during read-side list traversal if the object in concern is pending destruction
-after one or more grace periods. One such example can be found in the timerfd
-subsystem. When a ``CLOCK_REALTIME`` clock is reprogrammed - for example due to
-setting of the system time, then all programmed timerfds that depend on this
-clock get triggered and processes waiting on them to expire are woken up in
-advance of their scheduled expiry. To facilitate this, all such timers are added
-to an RCU-managed ``cancel_list`` when they are setup in
+For some use cases, reader performance can be improved by skipping
+stale objects during read-side list traversal, where stale objects
+are those that will be removed and destroyed after one or more grace
+periods. One such example can be found in the timerfd subsystem. When a
+``CLOCK_REALTIME`` clock is reprogrammed (for example due to setting
+of the system time) then all programmed ``timerfds`` that depend on
+this clock get triggered and processes waiting on them are awakened in
+advance of their scheduled expiry. To facilitate this, all such timers
+are added to an RCU-managed ``cancel_list`` when they are setup in
 ``timerfd_setup_cancel()``::
 
 	static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags)
 	{
 		spin_lock(&ctx->cancel_lock);
-		if ((ctx->clockid == CLOCK_REALTIME &&
+		if ((ctx->clockid == CLOCK_REALTIME ||
+		     ctx->clockid == CLOCK_REALTIME_ALARM) &&
 		    (flags & TFD_TIMER_ABSTIME) && (flags & TFD_TIMER_CANCEL_ON_SET)) {
 			if (!ctx->might_cancel) {
 				ctx->might_cancel = true;
@@ -382,13 +407,16 @@ to an RCU-managed ``cancel_list`` when they are setup in
 				list_add_rcu(&ctx->clist, &cancel_list);
 				spin_unlock(&cancel_lock);
 			}
+		} else {
+			__timerfd_remove_cancel(ctx);
 		}
 		spin_unlock(&ctx->cancel_lock);
 	}
 
-When a timerfd is freed (fd is closed), then the ``might_cancel`` flag of the
-timerfd object is cleared, the object removed from the ``cancel_list`` and
-destroyed::
+When a timerfd is freed (fd is closed), then the ``might_cancel``
+flag of the timerfd object is cleared, the object removed from the
+``cancel_list`` and destroyed, as shown in this simplified and inlined
+version of timerfd_release()::
 
 	int timerfd_release(struct inode *inode, struct file *file)
 	{
@@ -403,7 +431,10 @@ destroyed::
 		}
 		spin_unlock(&ctx->cancel_lock);
 
-		hrtimer_cancel(&ctx->t.tmr);
+		if (isalarm(ctx))
+			alarm_cancel(&ctx->t.alarm);
+		else
+			hrtimer_cancel(&ctx->t.tmr);
 		kfree_rcu(ctx, rcu);
 		return 0;
 	}
@@ -416,6 +447,7 @@ objects::
 
 	void timerfd_clock_was_set(void)
 	{
+		ktime_t moffs = ktime_mono_to_real(0);
 		struct timerfd_ctx *ctx;
 		unsigned long flags;
 
@@ -424,7 +456,7 @@ objects::
 			if (!ctx->might_cancel)
 				continue;
 			spin_lock_irqsave(&ctx->wqh.lock, flags);
-			if (ctx->moffs != ktime_mono_to_real(0)) {
+			if (ctx->moffs != moffs) {
 				ctx->moffs = KTIME_MAX;
 				ctx->ticks++;
 				wake_up_locked_poll(&ctx->wqh, EPOLLIN);
@@ -434,10 +466,10 @@ objects::
 		rcu_read_unlock();
 	}
 
-The key point here is, because RCU-traversal of the ``cancel_list`` happens
-while objects are being added and removed to the list, sometimes the traversal
-can step on an object that has been removed from the list. In this example, it
-is seen that it is better to skip such objects using a flag.
+The key point is that because RCU-protected traversal of the
+``cancel_list`` happens concurrently with object addition and removal,
+sometimes the traversal can access an object that has been removed from
+the list. In this example, a flag is used to skip such objects.
 
 
 Summary

Documentation/RCU/lockdep.rst

@@ -17,7 +17,9 @@ state::
 	rcu_read_lock_held() for normal RCU.
 	rcu_read_lock_bh_held() for RCU-bh.
 	rcu_read_lock_sched_held() for RCU-sched.
+	rcu_read_lock_any_held() for any of normal RCU, RCU-bh, and RCU-sched.
 	srcu_read_lock_held() for SRCU.
+	rcu_read_lock_trace_held() for RCU Tasks Trace.
 
 These functions are conservative, and will therefore return 1 if they
 aren't certain (for example, if CONFIG_DEBUG_LOCK_ALLOC is not set).
@@ -53,6 +55,8 @@ checking of rcu_dereference() primitives:
 		is invoked by both SRCU readers and updaters.
 	rcu_dereference_raw(p):
 		Don't check.  (Use sparingly, if at all.)
+	rcu_dereference_raw_check(p):
+		Don't do lockdep at all.  (Use sparingly, if at all.)
 	rcu_dereference_protected(p, c):
 		Use explicit check expression "c", and omit all barriers
 		and compiler constraints.  This is useful when the data

Documentation/accel/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+Compute Accelerators
+====================
+
+.. toctree::
+   :maxdepth: 1
+
+   introduction
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`

Documentation/accel/introduction.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+============
+Introduction
+============
+
+The Linux compute accelerators subsystem is designed to expose compute
+accelerators in a common way to user-space and provide a common set of
+functionality.
+
+These devices can be either stand-alone ASICs or IP blocks inside an SoC/GPU.
+Although these devices are typically designed to accelerate
+Machine-Learning (ML) and/or Deep-Learning (DL) computations, the accel layer
+is not limited to handling these types of accelerators.
+
+Typically, a compute accelerator will belong to one of the following
+categories:
+
+- Edge AI - doing inference at an edge device. It can be an embedded ASIC/FPGA,
+  or an IP inside a SoC (e.g. laptop web camera). These devices
+  are typically configured using registers and can work with or without DMA.
+
+- Inference data-center - single/multi user devices in a large server. This
+  type of device can be stand-alone or an IP inside a SoC or a GPU. It will
+  have on-board DRAM (to hold the DL topology), DMA engines and
+  command submission queues (either kernel or user-space queues).
+  It might also have an MMU to manage multiple users and might also enable
+  virtualization (SR-IOV) to support multiple VMs on the same device. In
+  addition, these devices will usually have some tools, such as profiler and
+  debugger.
+
+- Training data-center - Similar to Inference data-center cards, but typically
+  have more computational power and memory b/w (e.g. HBM) and will likely have
+  a method of scaling-up/out, i.e. connecting to other training cards inside
+  the server or in other servers, respectively.
+
+All these devices typically have different runtime user-space software stacks,
+that are tailored-made to their h/w. In addition, they will also probably
+include a compiler to generate programs to their custom-made computational
+engines. Typically, the common layer in user-space will be the DL frameworks,
+such as PyTorch and TensorFlow.
+
+Sharing code with DRM
+=====================
+
+Because this type of devices can be an IP inside GPUs or have similar
+characteristics as those of GPUs, the accel subsystem will use the
+DRM subsystem's code and functionality. i.e. the accel core code will
+be part of the DRM subsystem and an accel device will be a new type of DRM
+device.
+
+This will allow us to leverage the extensive DRM code-base and
+collaborate with DRM developers that have experience with this type of
+devices. In addition, new features that will be added for the accelerator
+drivers can be of use to GPU drivers as well.
+
+Differentiation from GPUs
+=========================
+
+Because we want to prevent the extensive user-space graphic software stack
+from trying to use an accelerator as a GPU, the compute accelerators will be
+differentiated from GPUs by using a new major number and new device char files.
+
+Furthermore, the drivers will be located in a separate place in the kernel
+tree - drivers/accel/.
+
+The accelerator devices will be exposed to the user space with the dedicated
+261 major number and will have the following convention:
+
+- device char files - /dev/accel/accel*
+- sysfs             - /sys/class/accel/accel*/
+- debugfs           - /sys/kernel/debug/accel/accel*/
+
+Getting Started
+===============
+
+First, read the DRM documentation at Documentation/gpu/index.rst.
+Not only it will explain how to write a new DRM driver but it will also
+contain all the information on how to contribute, the Code Of Conduct and
+what is the coding style/documentation. All of that is the same for the
+accel subsystem.
+
+Second, make sure the kernel is configured with CONFIG_DRM_ACCEL.
+
+To expose your device as an accelerator, two changes are needed to
+be done in your driver (as opposed to a standard DRM driver):
+
+- Add the DRIVER_COMPUTE_ACCEL feature flag in your drm_driver's
+  driver_features field. It is important to note that this driver feature is
+  mutually exclusive with DRIVER_RENDER and DRIVER_MODESET. Devices that want
+  to expose both graphics and compute device char files should be handled by
+  two drivers that are connected using the auxiliary bus framework.
+
+- Change the open callback in your driver fops structure to accel_open().
+  Alternatively, your driver can use DEFINE_DRM_ACCEL_FOPS macro to easily
+  set the correct function operations pointers structure.
+
+External References
+===================
+
+email threads
+-------------
+
+* `Initial discussion on the New subsystem for acceleration devices <https://lkml.org/lkml/2022/7/31/83>`_ - Oded Gabbay (2022)
+* `patch-set to add the new subsystem <https://lkml.org/lkml/2022/10/22/544>`_ - Oded Gabbay (2022)
+
+Conference talks
+----------------
+
+* `LPC 2022 Accelerators BOF outcomes summary <https://airlied.blogspot.com/2022/09/accelerators-bof-outcomes-summary.html>`_ - Dave Airlie (2022)

Documentation/admin-guide/blockdev/zram.rst

@@ -348,8 +348,13 @@ this can be accomplished with::
 
         echo huge_idle > /sys/block/zramX/writeback
 
+If a user chooses to writeback only incompressible pages (pages that none of
+algorithms can compress) this can be accomplished with::
+
+	echo incompressible > /sys/block/zramX/writeback
+
 If an admin wants to write a specific page in zram device to the backing device,
-they could write a page index into the interface.
+they could write a page index into the interface::
 
 	echo "page_index=1251" > /sys/block/zramX/writeback
 
@@ -401,6 +406,87 @@ budget in next setting is user's job.
 If admin wants to measure writeback count in a certain period, they could
 know it via /sys/block/zram0/bd_stat's 3rd column.
 
+recompression
+-------------
+
+With CONFIG_ZRAM_MULTI_COMP, zram can recompress pages using alternative
+(secondary) compression algorithms. The basic idea is that alternative
+compression algorithm can provide better compression ratio at a price of
+(potentially) slower compression/decompression speeds. Alternative compression
+algorithm can, for example, be more successful compressing huge pages (those
+that default algorithm failed to compress). Another application is idle pages
+recompression - pages that are cold and sit in the memory can be recompressed
+using more effective algorithm and, hence, reduce zsmalloc memory usage.
+
+With CONFIG_ZRAM_MULTI_COMP, zram supports up to 4 compression algorithms:
+one primary and up to 3 secondary ones. Primary zram compressor is explained
+in "3) Select compression algorithm", secondary algorithms are configured
+using recomp_algorithm device attribute.
+
+Example:::
+
+	#show supported recompression algorithms
+	cat /sys/block/zramX/recomp_algorithm
+	#1: lzo lzo-rle lz4 lz4hc [zstd]
+	#2: lzo lzo-rle lz4 [lz4hc] zstd
+
+Alternative compression algorithms are sorted by priority. In the example
+above, zstd is used as the first alternative algorithm, which has priority
+of 1, while lz4hc is configured as a compression algorithm with priority 2.
+Alternative compression algorithm's priority is provided during algorithms
+configuration:::
+
+	#select zstd recompression algorithm, priority 1
+	echo "algo=zstd priority=1" > /sys/block/zramX/recomp_algorithm
+
+	#select deflate recompression algorithm, priority 2
+	echo "algo=deflate priority=2" > /sys/block/zramX/recomp_algorithm
+
+Another device attribute that CONFIG_ZRAM_MULTI_COMP enables is recompress,
+which controls recompression.
+
+Examples:::
+
+	#IDLE pages recompression is activated by `idle` mode
+	echo "type=idle" > /sys/block/zramX/recompress
+
+	#HUGE pages recompression is activated by `huge` mode
+	echo "type=huge" > /sys/block/zram0/recompress
+
+	#HUGE_IDLE pages recompression is activated by `huge_idle` mode
+	echo "type=huge_idle" > /sys/block/zramX/recompress
+
+The number of idle pages can be significant, so user-space can pass a size
+threshold (in bytes) to the recompress knob: zram will recompress only pages
+of equal or greater size:::
+
+	#recompress all pages larger than 3000 bytes
+	echo "threshold=3000" > /sys/block/zramX/recompress
+
+	#recompress idle pages larger than 2000 bytes
+	echo "type=idle threshold=2000" > /sys/block/zramX/recompress
+
+Recompression of idle pages requires memory tracking.
+
+During re-compression for every page, that matches re-compression criteria,
+ZRAM iterates the list of registered alternative compression algorithms in
+order of their priorities. ZRAM stops either when re-compression was
+successful (re-compressed object is smaller in size than the original one)
+and matches re-compression criteria (e.g. size threshold) or when there are
+no secondary algorithms left to try. If none of the secondary algorithms can
+successfully re-compressed the page such a page is marked as incompressible,
+so ZRAM will not attempt to re-compress it in the future.
+
+This re-compression behaviour, when it iterates through the list of
+registered compression algorithms, increases our chances of finding the
+algorithm that successfully compresses a particular page. Sometimes, however,
+it is convenient (and sometimes even necessary) to limit recompression to
+only one particular algorithm so that it will not try any other algorithms.
+This can be achieved by providing a algo=NAME parameter:::
+
+	#use zstd algorithm only (if registered)
+	echo "type=huge algo=zstd" > /sys/block/zramX/recompress
+
 memory tracking
 ===============
 
@@ -411,9 +497,11 @@ pages of the process with*pagemap.
 If you enable the feature, you could see block state via
 /sys/kernel/debug/zram/zram0/block_state". The output is as follows::
 
-	  300    75.033841 .wh.
-	  301    63.806904 s...
-	  302    63.806919 ..hi
+	  300    75.033841 .wh...
+	  301    63.806904 s.....
+	  302    63.806919 ..hi..
+	  303    62.801919 ....r.
+	  304   146.781902 ..hi.n
 
 First column
 	zram's block index.
@@ -430,6 +518,10 @@ Third column
 		huge page
 	i:
 		idle page
+	r:
+		recompressed page (secondary compression algorithm)
+	n:
+		none (including secondary) of algorithms could compress it
 
 First line of above example says 300th block is accessed at 75.033841sec
 and the block's state is huge so it is written back to the backing

Documentation/admin-guide/bootconfig.rst

@@ -229,7 +229,7 @@ In addition to the kernel command line, the boot config can be used for
 passing the kernel parameters. All the key-value pairs under ``kernel``
 key will be passed to kernel cmdline directly. Moreover, the key-value
 pairs under ``init`` will be passed to init process via the cmdline.
-The parameters are concatinated with user-given kernel cmdline string
+The parameters are concatenated with user-given kernel cmdline string
 as the following order, so that the command line parameter can override
 bootconfig parameters (this depends on how the subsystem handles parameters
 but in general, earlier parameter will be overwritten by later one.)::

Documentation/admin-guide/cgroup-v1/memory.rst

@@ -543,7 +543,8 @@ inactive_anon	# of bytes of anonymous and swap cache memory on inactive
 		LRU list.
 active_anon	# of bytes of anonymous and swap cache memory on active
 		LRU list.
-inactive_file	# of bytes of file-backed memory on inactive LRU list.
+inactive_file	# of bytes of file-backed memory and MADV_FREE anonymous memory(
+                LazyFree pages) on inactive LRU list.
 active_file	# of bytes of file-backed memory on active LRU list.
 unevictable	# of bytes of memory that cannot be reclaimed (mlocked etc).
 =============== ===============================================================

Documentation/admin-guide/cgroup-v2.rst

@@ -1245,17 +1245,13 @@ PAGE_SIZE multiple when read back.
 	This is a simple interface to trigger memory reclaim in the
 	target cgroup.
 
-	This file accepts a single key, the number of bytes to reclaim.
-	No nested keys are currently supported.
+	This file accepts a string which contains the number of bytes to
+	reclaim.
 
 	Example::
 
 	  echo "1G" > memory.reclaim
 
-	The interface can be later extended with nested keys to
-	configure the reclaim behavior. For example, specify the
-	type of memory to reclaim from (anon, file, ..).
-
 	Please note that the kernel can over or under reclaim from
 	the target cgroup. If less bytes are reclaimed than the
 	specified amount, -EAGAIN is returned.
@@ -1267,6 +1263,13 @@ PAGE_SIZE multiple when read back.
 	This means that the networking layer will not adapt based on
 	reclaim induced by memory.reclaim.
 
+	This file also allows the user to specify the nodes to reclaim from,
+	via the 'nodes=' key, for example::
+
+	  echo "1G nodes=0,1" > memory.reclaim
+
+	The above instructs the kernel to reclaim memory from nodes 0,1.
+
   memory.peak
 	A read-only single value file which exists on non-root
 	cgroups.
@@ -1488,12 +1491,18 @@ PAGE_SIZE multiple when read back.
 	  pgscan_direct (npn)
 		Amount of scanned pages directly  (in an inactive LRU list)
 
+	  pgscan_khugepaged (npn)
+		Amount of scanned pages by khugepaged  (in an inactive LRU list)
+
 	  pgsteal_kswapd (npn)
 		Amount of reclaimed pages by kswapd
 
 	  pgsteal_direct (npn)
 		Amount of reclaimed pages directly
 
+	  pgsteal_khugepaged (npn)
+		Amount of reclaimed pages by khugepaged
+
 	  pgfault (npn)
 		Total number of page faults incurred
 

Documentation/admin-guide/cifs/usage.rst

@@ -858,7 +858,7 @@ CIFS kernel module parameters
 These module parameters can be specified or modified either during the time of
 module loading or during the runtime by using the interface::
 
-	/proc/module/cifs/parameters/<param>
+	/sys/module/cifs/parameters/<param>
 
 i.e.::
 

Documentation/admin-guide/device-mapper/dm-init.rst

@@ -123,3 +123,11 @@ Other examples (per target):
     0 1638400 verity 1 8:1 8:2 4096 4096 204800 1 sha256
     fb1a5a0f00deb908d8b53cb270858975e76cf64105d412ce764225d53b8f3cfd
     51934789604d1b92399c52e7cb149d1b3a1b74bbbcb103b2a0aaacbed5c08584
+
+For setups using device-mapper on top of asynchronously probed block
+devices (MMC, USB, ..), it may be necessary to tell dm-init to
+explicitly wait for them to become available before setting up the
+device-mapper tables. This can be done with the "dm-mod.waitfor="
+module parameter, which takes a list of devices to wait for::
+
+  dm-mod.waitfor=<device1>[,..,<deviceN>]

Documentation/admin-guide/devices.txt

@@ -3080,6 +3080,11 @@
 		  ...
 		  255 = /dev/osd255	256th OSD Device
 
+ 261 char	Compute Acceleration Devices
+		  0 = /dev/accel/accel0	First acceleration device
+		  1 = /dev/accel/accel1	Second acceleration device
+		    ...
+
  384-511 char	RESERVED FOR DYNAMIC ASSIGNMENT
 		Character devices that request a dynamic allocation of major
 		number will take numbers starting from 511 and downward,

Documentation/admin-guide/hw_random.rst

-==========================================================
-Linux support for random number generator in i8xx chipsets
-==========================================================
+=================================
+Hardware random number generators
+=================================
 
 Introduction
 ============

Documentation/admin-guide/kdump/vmcoreinfo.rst

@@ -595,3 +595,32 @@ X2TLB
 -----
 
 Indicates whether the crashed kernel enabled SH extended mode.
+
+RISCV64
+=======
+
+VA_BITS
+-------
+
+The maximum number of bits for virtual addresses. Used to compute the
+virtual memory ranges.
+
+PAGE_OFFSET
+-----------
+
+Indicates the virtual kernel start address of the direct-mapped RAM region.
+
+phys_ram_base
+-------------
+
+Indicates the start physical RAM address.
+
+MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END|KERNEL_LINK_ADDR
+----------------------------------------------------------------------------------------------
+
+Used to get the correct ranges:
+
+  * MODULES_VADDR ~ MODULES_END : Kernel module space.
+  * VMALLOC_START ~ VMALLOC_END : vmalloc() / ioremap() space.
+  * VMEMMAP_START ~ VMEMMAP_END : vmemmap space, used for struct page array.
+  * KERNEL_LINK_ADDR : start address of Kernel link and BPF

Documentation/admin-guide/kernel-parameters.txt

@@ -703,6 +703,17 @@
 	condev=		[HW,S390] console device
 	conmode=
 
+	con3215_drop=	[S390] 3215 console drop mode.
+			Format: y|n|Y|N|1|0
+			When set to true, drop data on the 3215 console when
+			the console buffer is full. In this case the
+			operator using a 3270 terminal emulator (for example
+			x3270) does not have to enter the clear key for the
+			console output to advance and the kernel to continue.
+			This leads to a much faster boot time when a 3270
+			terminal emulator is active. If no 3270 terminal
+			emulator is used, this parameter has no effect.
+
 	console=	[KNL] Output console device and options.
 
 		tty<n>	Use the virtual console device <n>.
@@ -831,7 +842,7 @@
 			memory region [offset, offset + size] for that kernel
 			image. If '@offset' is omitted, then a suitable offset
 			is selected automatically.
-			[KNL, X86-64] Select a region under 4G first, and
+			[KNL, X86-64, ARM64] Select a region under 4G first, and
 			fall back to reserve region above 4G when '@offset'
 			hasn't been specified.
 			See Documentation/admin-guide/kdump/kdump.rst for further details.
@@ -851,26 +862,23 @@
 			available.
 			It will be ignored if crashkernel=X is specified.
 	crashkernel=size[KMG],low
-			[KNL, X86-64] range under 4G. When crashkernel=X,high
+			[KNL, X86-64, ARM64] range under 4G. When crashkernel=X,high
 			is passed, kernel could allocate physical memory region
 			above 4G, that cause second kernel crash on system
 			that require some amount of low memory, e.g. swiotlb
 			requires at least 64M+32K low memory, also enough extra
 			low memory is needed to make sure DMA buffers for 32-bit
 			devices won't run out. Kernel would try to allocate
-			at least 256M below 4G automatically.
+			default	size of memory below 4G automatically. The default
+			size is	platform dependent.
+			  --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
+			  --> arm64: 128MiB
 			This one lets the user specify own low range under 4G
 			for second kernel instead.
 			0: to disable low allocation.
 			It will be ignored when crashkernel=X,high is not used
 			or memory reserved is below 4G.
 
-			[KNL, ARM64] range in low memory.
-			This one lets the user specify a low range in the
-			DMA zone for the crash dump kernel.
-			It will be ignored when crashkernel=X,high is not used
-			or memory reserved is located in the DMA zones.
-
 	cryptomgr.notests
 			[KNL] Disable crypto self-tests
 
@@ -1042,6 +1050,11 @@
 			them frequently to increase the rate of SLB faults
 			on kernel addresses.
 
+	stress_hpt	[PPC]
+			Limits the number of kernel HPT entries in the hash
+			page table to increase the rate of hash page table
+			faults on kernel addresses.
+
 	disable=	[IPV6]
 			See Documentation/networking/ipv6.rst.
 
@@ -2300,7 +2313,13 @@
 			Provide an override to the IOAPIC-ID<->DEVICE-ID
 			mapping provided in the IVRS ACPI table.
 			By default, PCI segment is 0, and can be omitted.
-			For example:
+
+			For example, to map IOAPIC-ID decimal 10 to
+			PCI segment 0x1 and PCI device 00:14.0,
+			write the parameter as:
+				ivrs_ioapic=10@0001:00:14.0
+
+			Deprecated formats:
 			* To map IOAPIC-ID decimal 10 to PCI device 00:14.0
 			  write the parameter as:
 				ivrs_ioapic[10]=00:14.0
@@ -2312,7 +2331,13 @@
 			Provide an override to the HPET-ID<->DEVICE-ID
 			mapping provided in the IVRS ACPI table.
 			By default, PCI segment is 0, and can be omitted.
-			For example:
+
+			For example, to map HPET-ID decimal 10 to
+			PCI segment 0x1 and PCI device 00:14.0,
+			write the parameter as:
+				ivrs_hpet=10@0001:00:14.0
+
+			Deprecated formats:
 			* To map HPET-ID decimal 0 to PCI device 00:14.0
 			  write the parameter as:
 				ivrs_hpet[0]=00:14.0
@@ -2323,15 +2348,20 @@
 	ivrs_acpihid	[HW,X86-64]
 			Provide an override to the ACPI-HID:UID<->DEVICE-ID
 			mapping provided in the IVRS ACPI table.
+			By default, PCI segment is 0, and can be omitted.
 
 			For example, to map UART-HID:UID AMD0020:0 to
 			PCI segment 0x1 and PCI device ID 00:14.5,
 			write the parameter as:
-				ivrs_acpihid[0001:00:14.5]=AMD0020:0
+				ivrs_acpihid=AMD0020:0@0001:00:14.5
 
-			By default, PCI segment is 0, and can be omitted.
-			For example, PCI device 00:14.5 write the parameter as:
+			Deprecated formats:
+			* To map UART-HID:UID AMD0020:0 to PCI segment is 0,
+			  PCI device ID 00:14.5, write the parameter as:
 				ivrs_acpihid[00:14.5]=AMD0020:0
+			* To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
+			  PCI device ID 00:14.5, write the parameter as:
+				ivrs_acpihid[0001:00:14.5]=AMD0020:0
 
 	js=		[HW,JOY] Analog joystick
 			See Documentation/input/joydev/joystick.rst.
@@ -4569,17 +4599,15 @@
 
 	ramdisk_start=	[RAM] RAM disk image start address
 
-	random.trust_cpu={on,off}
-			[KNL] Enable or disable trusting the use of the
-			CPU's random number generator (if available) to
-			fully seed the kernel's CRNG. Default is controlled
-			by CONFIG_RANDOM_TRUST_CPU.
+	random.trust_cpu=off
+			[KNL] Disable trusting the use of the CPU's
+			random number generator (if available) to
+			initialize the kernel's RNG.
 
-	random.trust_bootloader={on,off}
-			[KNL] Enable or disable trusting the use of a
-			seed passed by the bootloader (if available) to
-			fully seed the kernel's CRNG. Default is controlled
-			by CONFIG_RANDOM_TRUST_BOOTLOADER.
+	random.trust_bootloader=off
+			[KNL] Disable trusting the use of the a seed
+			passed by the bootloader (if available) to
+			initialize the kernel's RNG.
 
 	randomize_kstack_offset=
 			[KNL] Enable or disable kernel stack offset
@@ -6260,6 +6288,25 @@
 			See also Documentation/trace/ftrace.rst "trace options"
 			section.
 
+	trace_trigger=[trigger-list]
+			[FTRACE] Add a event trigger on specific events.
+			Set a trigger on top of a specific event, with an optional
+			filter.
+
+			The format is is "trace_trigger=<event>.<trigger>[ if <filter>],..."
+			Where more than one trigger may be specified that are comma deliminated.
+
+			For example:
+
+			  trace_trigger="sched_switch.stacktrace if prev_state == 2"
+
+			The above will enable the "stacktrace" trigger on the "sched_switch"
+			event but only trigger it if the "prev_state" of the "sched_switch"
+			event is "2" (TASK_UNINTERUPTIBLE).
+
+			See also "Event triggers" in Documentation/trace/events.rst
+
+
 	traceoff_on_warning
 			[FTRACE] enable this option to disable tracing when a
 			warning is hit. This turns off "tracing_on". Tracing can
@@ -6962,3 +7009,14 @@
 				memory, and other data can't be written using
 				xmon commands.
 			off	xmon is disabled.
+
+	amd_pstate=	[X86]
+			disable
+			  Do not enable amd_pstate as the default
+			  scaling driver for the supported processors
+			passive
+			  Use amd_pstate as a scaling driver, driver requests a
+			  desired performance on this abstract scale and the power
+			  management firmware translates the requests into actual
+			  hardware states (core frequency, data fabric and memory
+			  clocks etc.)

Documentation/admin-guide/media/cec-drivers.rst

-.. SPDX-License-Identifier: GPL-2.0
-
-=================================
-CEC driver-specific documentation
-=================================
-
-.. toctree::
-	:maxdepth: 2
-
-	pulse8-cec

Documentation/admin-guide/media/cec.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+========
+HDMI CEC
+========
+
+Supported hardware in mainline
+==============================
+
+HDMI Transmitters:
+
+- Exynos4
+- Exynos5
+- STIH4xx HDMI CEC
+- V4L2 adv7511 (same HW, but a different driver from the drm adv7511)
+- stm32
+- Allwinner A10 (sun4i)
+- Raspberry Pi
+- dw-hdmi (Synopsis IP)
+- amlogic (meson ao-cec and ao-cec-g12a)
+- drm adv7511/adv7533
+- omap4
+- tegra
+- rk3288, rk3399
+- tda998x
+- DisplayPort CEC-Tunneling-over-AUX on i915, nouveau and amdgpu
+- ChromeOS EC CEC
+- CEC for SECO boards (UDOO x86).
+- Chrontel CH7322
+
+
+HDMI Receivers:
+
+- adv7604/11/12
+- adv7842
+- tc358743
+
+USB Dongles (see below for additional information on how to use these
+dongles):
+
+- Pulse-Eight: the pulse8-cec driver implements the following module option:
+  ``persistent_config``: by default this is off, but when set to 1 the driver
+  will store the current settings to the device's internal eeprom and restore
+  it the next time the device is connected to the USB port.
+- RainShadow Tech. Note: this driver does not support the persistent_config
+  module option of the Pulse-Eight driver. The hardware supports it, but I
+  have no plans to add this feature. But I accept patches :-)
+
+Miscellaneous:
+
+- vivid: emulates a CEC receiver and CEC transmitter.
+  Can be used to test CEC applications without actual CEC hardware.
+
+- cec-gpio. If the CEC pin is hooked up to a GPIO pin then
+  you can control the CEC line through this driver. This supports error
+  injection as well.
+
+
+Utilities
+=========
+
+Utilities are available here: https://git.linuxtv.org/v4l-utils.git
+
+``utils/cec-ctl``: control a CEC device
+
+``utils/cec-compliance``: test compliance of a remote CEC device
+
+``utils/cec-follower``: emulate a CEC follower device
+
+Note that ``cec-ctl`` has support for the CEC Hospitality Profile as is
+used in some hotel displays. See http://www.htng.org.
+
+Note that the libcec library (https://github.com/Pulse-Eight/libcec) supports
+the linux CEC framework.
+
+If you want to get the CEC specification, then look at the References of
+the HDMI wikipedia page: https://en.wikipedia.org/wiki/HDMI. CEC is part
+of the HDMI specification. HDMI 1.3 is freely available (very similar to
+HDMI 1.4 w.r.t. CEC) and should be good enough for most things.
+
+
+DisplayPort to HDMI Adapters with working CEC
+=============================================
+
+Background: most adapters do not support the CEC Tunneling feature,
+and of those that do many did not actually connect the CEC pin.
+Unfortunately, this means that while a CEC device is created, it
+is actually all alone in the world and will never be able to see other
+CEC devices.
+
+This is a list of known working adapters that have CEC Tunneling AND
+that properly connected the CEC pin. If you find adapters that work
+but are not in this list, then drop me a note.
+
+To test: hook up your DP-to-HDMI adapter to a CEC capable device
+(typically a TV), then run::
+
+	cec-ctl --playback	# Configure the PC as a CEC Playback device
+	cec-ctl -S		# Show the CEC topology
+
+The ``cec-ctl -S`` command should show at least two CEC devices,
+ourselves and the CEC device you are connected to (i.e. typically the TV).
+
+General note: I have only seen this work with the Parade PS175, PS176 and
+PS186 chipsets and the MegaChips 2900. While MegaChips 28x0 claims CEC support,
+I have never seen it work.
+
+USB-C to HDMI
+-------------
+
+Samsung Multiport Adapter EE-PW700: https://www.samsung.com/ie/support/model/EE-PW700BBEGWW/
+
+Kramer ADC-U31C/HF: https://www.kramerav.com/product/ADC-U31C/HF
+
+Club3D CAC-2504: https://www.club-3d.com/en/detail/2449/usb_3.1_type_c_to_hdmi_2.0_uhd_4k_60hz_active_adapter/
+
+DisplayPort to HDMI
+-------------------
+
+Club3D CAC-1080: https://www.club-3d.com/en/detail/2442/displayport_1.4_to_hdmi_2.0b_hdr/
+
+CableCreation (SKU: CD0712): https://www.cablecreation.com/products/active-displayport-to-hdmi-adapter-4k-hdr
+
+HP DisplayPort to HDMI True 4k Adapter (P/N 2JA63AA): https://www.hp.com/us-en/shop/pdp/hp-displayport-to-hdmi-true-4k-adapter
+
+Mini-DisplayPort to HDMI
+------------------------
+
+Club3D CAC-1180: https://www.club-3d.com/en/detail/2443/mini_displayport_1.4_to_hdmi_2.0b_hdr/
+
+Note that passive adapters will never work, you need an active adapter.
+
+The Club3D adapters in this list are all MegaChips 2900 based. Other Club3D adapters
+are PS176 based and do NOT have the CEC pin hooked up, so only the three Club3D
+adapters above are known to work.
+
+I suspect that MegaChips 2900 based designs in general are likely to work
+whereas with the PS176 it is more hit-and-miss (mostly miss). The PS186 is
+likely to have the CEC pin hooked up, it looks like they changed the reference
+design for that chipset.
+
+
+USB CEC Dongles
+===============
+
+These dongles appear as ``/dev/ttyACMX`` devices and need the ``inputattach``
+utility to create the ``/dev/cecX`` devices. Support for the Pulse-Eight
+has been added to ``inputattach`` 1.6.0. Support for the Rainshadow Tech has
+been added to ``inputattach`` 1.6.1.
+
+You also need udev rules to automatically start systemd services::
+
+	SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="2548", ATTRS{idProduct}=="1002", ACTION=="add", TAG+="systemd", ENV{SYSTEMD_WANTS}+="pulse8-cec-inputattach@%k.service"
+	SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="2548", ATTRS{idProduct}=="1001", ACTION=="add", TAG+="systemd", ENV{SYSTEMD_WANTS}+="pulse8-cec-inputattach@%k.service"
+	SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="04d8", ATTRS{idProduct}=="ff59", ACTION=="add", TAG+="systemd", ENV{SYSTEMD_WANTS}+="rainshadow-cec-inputattach@%k.service"
+
+and these systemd services:
+
+For Pulse-Eight make /lib/systemd/system/pulse8-cec-inputattach@.service::
+
+	[Unit]
+	Description=inputattach for pulse8-cec device on %I
+
+	[Service]
+	Type=simple
+	ExecStart=/usr/bin/inputattach --pulse8-cec /dev/%I
+
+For the RainShadow Tech make /lib/systemd/system/rainshadow-cec-inputattach@.service::
+
+	[Unit]
+	Description=inputattach for rainshadow-cec device on %I
+
+	[Service]
+	Type=simple
+	ExecStart=/usr/bin/inputattach --rainshadow-cec /dev/%I
+
+
+For proper suspend/resume support create: /lib/systemd/system/restart-cec-inputattach.service::
+
+	[Unit]
+	Description=restart inputattach for cec devices
+	After=suspend.target
+
+	[Service]
+	Type=forking
+	ExecStart=/bin/bash -c 'for d in /dev/serial/by-id/usb-Pulse-Eight*; do /usr/bin/inputattach --daemon --pulse8-cec $d; done; for d in /dev/serial/by-id/usb-RainShadow_Tech*; do /usr/bin/inputattach --daemon --rainshadow-cec $d; done'
+
+	[Install]
+	WantedBy=suspend.target
+
+And run ``systemctl enable restart-cec-inputattach``.
+
+To automatically set the physical address of the CEC device whenever the
+EDID changes, you can use ``cec-ctl`` with the ``-E`` option::
+
+	cec-ctl -E /sys/class/drm/card0-DP-1/edid
+
+This assumes the dongle is connected to the card0-DP-1 output (``xrandr`` will tell
+you which output is used) and it will poll for changes to the EDID and update
+the Physical Address whenever they occur.
+
+To automatically run this command you can use cron. Edit crontab with
+``crontab -e`` and add this line::
+
+	@reboot /usr/local/bin/cec-ctl -E /sys/class/drm/card0-DP-1/edid
+
+This only works for display drivers that expose the EDID in ``/sys/class/drm``,
+such as the i915 driver.
+
+
+CEC Without HPD
+===============
+
+Some displays when in standby mode have no HDMI Hotplug Detect signal, but
+CEC is still enabled so connected devices can send an <Image View On> CEC
+message in order to wake up such displays. Unfortunately, not all CEC
+adapters can support this. An example is the Odroid-U3 SBC that has a
+level-shifter that is powered off when the HPD signal is low, thus
+blocking the CEC pin. Even though the SoC can use CEC without a HPD,
+the level-shifter will prevent this from functioning.
+
+There is a CEC capability flag to signal this: ``CEC_CAP_NEEDS_HPD``.
+If set, then the hardware cannot wake up displays with this behavior.
+
+Note for CEC application implementers: the <Image View On> message must
+be the first message you send, don't send any other messages before.
+Certain very bad but unfortunately not uncommon CEC implementations
+get very confused if they receive anything else but this message and
+they won't wake up.
+
+When writing a driver it can be tricky to test this. There are two
+ways to do this:
+
+1) Get a Pulse-Eight USB CEC dongle, connect an HDMI cable from your
+   device to the Pulse-Eight, but do not connect the Pulse-Eight to
+   the display.
+
+   Now configure the Pulse-Eight dongle::
+
+	cec-ctl -p0.0.0.0 --tv
+
+   and start monitoring::
+
+	sudo cec-ctl -M
+
+   On the device you are testing run::
+
+	cec-ctl --playback
+
+   It should report a physical address of f.f.f.f. Now run this
+   command::
+
+	cec-ctl -t0 --image-view-on
+
+   The Pulse-Eight should see the <Image View On> message. If not,
+   then something (hardware and/or software) is preventing the CEC
+   message from going out.
+
+   To make sure you have the wiring correct just connect the
+   Pulse-Eight to a CEC-enabled display and run the same command
+   on your device: now there is a HPD, so you should see the command
+   arriving at the Pulse-Eight.
+
+2) If you have another linux device supporting CEC without HPD, then
+   you can just connect your device to that device. Yes, you can connect
+   two HDMI outputs together. You won't have a HPD (which is what we
+   want for this test), but the second device can monitor the CEC pin.
+
+   Otherwise use the same commands as in 1.
+
+If CEC messages do not come through when there is no HPD, then you
+need to figure out why. Typically it is either a hardware restriction
+or the software powers off the CEC core when the HPD goes low. The
+first cannot be corrected of course, the second will likely required
+driver changes.
+
+
+Microcontrollers & CEC
+======================
+
+We have seen some CEC implementations in displays that use a microcontroller
+to sample the bus. This does not have to be a problem, but some implementations
+have timing issues. This is hard to discover unless you can hook up a low-level
+CEC debugger (see the next section).
+
+You will see cases where the CEC transmitter holds the CEC line high or low for
+a longer time than is allowed. For directed messages this is not a problem since
+if that happens the message will not be Acked and it will be retransmitted.
+For broadcast messages no such mechanism exists.
+
+It's not clear what to do about this. It is probably wise to transmit some
+broadcast messages twice to reduce the chance of them being lost. Specifically
+<Standby> and <Active Source> are candidates for that.
+
+
+Making a CEC debugger
+=====================
+
+By using a Raspberry Pi 2B/3/4 and some cheap components you can make
+your own low-level CEC debugger.
+
+Here is a picture of my setup:
+
+https://hverkuil.home.xs4all.nl/rpi3-cec.jpg
+
+It's a Raspberry Pi 3 together with a breadboard and some breadboard wires:
+
+http://www.dx.com/p/diy-40p-male-to-female-male-to-male-female-to-female-dupont-line-wire-3pcs-356089#.WYLOOXWGN7I
+
+Finally on of these HDMI female-female passthrough connectors (full soldering type 1):
+
+https://elabbay.myshopify.com/collections/camera/products/hdmi-af-af-v1a-hdmi-type-a-female-to-hdmi-type-a-female-pass-through-adapter-breakout-board?variant=45533926147
+
+We've tested this and it works up to 4kp30 (297 MHz). The quality is not high
+enough to pass-through 4kp60 (594 MHz).
+
+I also added an RTC and a breakout shield:
+
+https://www.amazon.com/Makerfire%C2%AE-Raspberry-Module-DS1307-Battery/dp/B00ZOXWHK4
+
+https://www.dx.com/p/raspberry-pi-gpio-expansion-board-breadboard-easy-multiplexing-board-one-to-three-with-screw-for-raspberry-pi-2-3-b-b-2729992.html#.YGRCG0MzZ7I
+
+These two are not needed but they make life a bit easier.
+
+If you want to monitor the HPD line as well, then you need one of these
+level shifters:
+
+https://www.adafruit.com/product/757
+
+(This is just where I got these components, there are many other places you
+can get similar things).
+
+The CEC pin of the HDMI connector needs to be connected to these pins:
+CE0/IO8 and CE1/IO7 (pull-up GPIOs). The (optional) HPD pin of the HDMI
+connector should be connected (via a level shifter to convert the 5V
+to 3.3V) to these pins: IO17 and IO27. The (optional) 5V pin of the HDMI
+connector should be connected (via a level shifter) to these pins: IO22
+and IO24. Monitoring the HPD an 5V lines is not necessary, but it is helpful.
+
+This kernel patch will hook up the cec-gpio driver correctly to
+e.g. ``arch/arm/boot/dts/bcm2837-rpi-3-b-plus.dts``::
+
+	cec-gpio@7 {
+		compatible = "cec-gpio";
+		cec-gpios = <&gpio 7 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
+		hpd-gpios = <&gpio 17 GPIO_ACTIVE_HIGH>;
+		v5-gpios = <&gpio 22 GPIO_ACTIVE_HIGH>;
+	};
+
+	cec-gpio@8 {
+		compatible = "cec-gpio";
+		cec-gpios = <&gpio 8 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
+		hpd-gpios = <&gpio 27 GPIO_ACTIVE_HIGH>;
+		v5-gpios = <&gpio 24 GPIO_ACTIVE_HIGH>;
+	};
+
+This dts change will enable two cec GPIO devices: I typically use one to
+send/receive CEC commands and the other to monitor. If you monitor using
+an unconfigured CEC adapter then it will use GPIO interrupts which makes
+monitoring very accurate.
+
+The documentation on how to use the error injection is here: :ref:`cec_pin_error_inj`.
+
+``cec-ctl --monitor-pin`` will do low-level CEC bus sniffing and analysis.
+You can also store the CEC traffic to file using ``--store-pin`` and analyze
+it later using ``--analyze-pin``.
+
+You can also use this as a full-fledged CEC device by configuring it
+using ``cec-ctl --tv -p0.0.0.0`` or ``cec-ctl --playback -p1.0.0.0``.

Documentation/admin-guide/media/index.rst

@@ -38,13 +38,14 @@ The media subsystem
 
 	remote-controller
 
+	cec
+
 	dvb
 
 	cardlist
 
 	v4l-drivers
 	dvb-drivers
-	cec-drivers
 
 **Copyright** |copy| 1999-2020 : LinuxTV Developers
 

Documentation/admin-guide/media/pulse8-cec.rst

-.. SPDX-License-Identifier: GPL-2.0
-
-Pulse-Eight CEC Adapter driver
-==============================
-
-The pulse8-cec driver implements the following module option:
-
-``persistent_config``
----------------------
-
-By default this is off, but when set to 1 the driver will store the current
-settings to the device's internal eeprom and restore it the next time the
-device is connected to the USB port.

Documentation/admin-guide/media/v4l-drivers.rst

@@ -31,4 +31,5 @@ Video4Linux (V4L) driver-specific documentation
 	si4713
 	si476x
 	vimc
+	visl
 	vivid

Documentation/admin-guide/media/vimc.rst

@@ -35,11 +35,11 @@ of commands fits for the default topology:
 
         media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
         media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
-        media-ctl -d platform:vimc -V '"Sensor B":0[fmt:SBGGR8_1X8/640x480]'
-        media-ctl -d platform:vimc -V '"Debayer B":0[fmt:SBGGR8_1X8/640x480]'
-        v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440
+        media-ctl -d platform:vimc -V '"Scaler":0[fmt:RGB888_1X24/640x480]'
+        media-ctl -d platform:vimc -V '"Scaler":0[crop:(100,50)/400x150]'
+        media-ctl -d platform:vimc -V '"Scaler":1[fmt:RGB888_1X24/300x700]'
+        v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=300,height=700
         v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
-        v4l2-ctl -z platform:vimc -d "Raw Capture 1" -v pixelformat=BA81
 
 Subdevices
 ----------

Documentation/admin-guide/media/visl.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+The Virtual Stateless Decoder Driver (visl)
+===========================================
+
+A virtual stateless decoder device for stateless uAPI development
+purposes.
+
+This tool's objective is to help the development and testing of
+userspace applications that use the V4L2 stateless API to decode media.
+
+A userspace implementation can use visl to run a decoding loop even when
+no hardware is available or when the kernel uAPI for the codec has not
+been upstreamed yet. This can reveal bugs at an early stage.
+
+This driver can also trace the contents of the V4L2 controls submitted
+to it.  It can also dump the contents of the vb2 buffers through a
+debugfs interface. This is in many ways similar to the tracing
+infrastructure available for other popular encode/decode APIs out there
+and can help develop a userspace application by using another (working)
+one as a reference.
+
+.. note::
+
+        No actual decoding of video frames is performed by visl. The
+        V4L2 test pattern generator is used to write various debug information
+        to the capture buffers instead.
+
+Module parameters
+-----------------
+
+- visl_debug: Activates debug info, printing various debug messages through
+  dprintk. Also controls whether per-frame debug info is shown. Defaults to off.
+  Note that enabling this feature can result in slow performance through serial.
+
+- visl_transtime_ms: Simulated process time in milliseconds. Slowing down the
+  decoding speed can be useful for debugging.
+
+- visl_dprintk_frame_start, visl_dprintk_frame_nframes: Dictates a range of
+  frames where dprintk is activated. This only controls the dprintk tracing on a
+  per-frame basis. Note that printing a lot of data can be slow through serial.
+
+- keep_bitstream_buffers: Controls whether bitstream (i.e. OUTPUT) buffers are
+  kept after a decoding session. Defaults to false so as to reduce the amount of
+  clutter. keep_bitstream_buffers == false works well when live debugging the
+  client program with GDB.
+
+- bitstream_trace_frame_start, bitstream_trace_nframes: Similar to
+  visl_dprintk_frame_start, visl_dprintk_nframes, but controls the dumping of
+  buffer data through debugfs instead.
+
+What is the default use case for this driver?
+---------------------------------------------
+
+This driver can be used as a way to compare different userspace implementations.
+This assumes that a working client is run against visl and that the ftrace and
+OUTPUT buffer data is subsequently used to debug a work-in-progress
+implementation.
+
+Information on reference frames, their timestamps, the status of the OUTPUT and
+CAPTURE queues and more can be read directly from the CAPTURE buffers.
+
+Supported codecs
+----------------
+
+The following codecs are supported:
+
+- FWHT
+- MPEG2
+- VP8
+- VP9
+- H.264
+- HEVC
+
+visl trace events
+-----------------
+The trace events are defined on a per-codec basis, e.g.:
+
+.. code-block:: bash
+
+        $ ls /sys/kernel/debug/tracing/events/ | grep visl
+        visl_fwht_controls
+        visl_h264_controls
+        visl_hevc_controls
+        visl_mpeg2_controls
+        visl_vp8_controls
+        visl_vp9_controls
+
+For example, in order to dump HEVC SPS data:
+
+.. code-block:: bash
+
+        $ echo 1 >  /sys/kernel/debug/tracing/events/visl_hevc_controls/v4l2_ctrl_hevc_sps/enable
+
+The SPS data will be dumped to the trace buffer, i.e.:
+
+.. code-block:: bash
+
+        $ cat /sys/kernel/debug/tracing/trace
+        video_parameter_set_id 0
+        seq_parameter_set_id 0
+        pic_width_in_luma_samples 1920
+        pic_height_in_luma_samples 1080
+        bit_depth_luma_minus8 0
+        bit_depth_chroma_minus8 0
+        log2_max_pic_order_cnt_lsb_minus4 4
+        sps_max_dec_pic_buffering_minus1 6
+        sps_max_num_reorder_pics 2
+        sps_max_latency_increase_plus1 0
+        log2_min_luma_coding_block_size_minus3 0
+        log2_diff_max_min_luma_coding_block_size 3
+        log2_min_luma_transform_block_size_minus2 0
+        log2_diff_max_min_luma_transform_block_size 3
+        max_transform_hierarchy_depth_inter 2
+        max_transform_hierarchy_depth_intra 2
+        pcm_sample_bit_depth_luma_minus1 0
+        pcm_sample_bit_depth_chroma_minus1 0
+        log2_min_pcm_luma_coding_block_size_minus3 0
+        log2_diff_max_min_pcm_luma_coding_block_size 0
+        num_short_term_ref_pic_sets 0
+        num_long_term_ref_pics_sps 0
+        chroma_format_idc 1
+        sps_max_sub_layers_minus1 0
+        flags AMP_ENABLED|SAMPLE_ADAPTIVE_OFFSET|TEMPORAL_MVP_ENABLED|STRONG_INTRA_SMOOTHING_ENABLED
+
+
+Dumping OUTPUT buffer data through debugfs
+------------------------------------------
+
+If the **VISL_DEBUGFS** Kconfig is enabled, visl will populate
+**/sys/kernel/debug/visl/bitstream** with OUTPUT buffer data according to the
+values of bitstream_trace_frame_start and bitstream_trace_nframes. This can
+highlight errors as broken clients may fail to fill the buffers properly.
+
+A single file is created for each processed OUTPUT buffer. Its name contains an
+integer that denotes the buffer sequence, i.e.:
+
+.. code-block:: c
+
+	snprintf(name, 32, "bitstream%d", run->src->sequence);
+
+Dumping the values is simply a matter of reading from the file, i.e.:
+
+For the buffer with sequence == 0:
+
+.. code-block:: bash
+
+        $ xxd /sys/kernel/debug/visl/bitstream/bitstream0
+        00000000: 2601 af04 d088 bc25 a173 0e41 a4f2 3274  &......%.s.A..2t
+        00000010: c668 cb28 e775 b4ac f53a ba60 f8fd 3aa1  .h.(.u...:.`..:.
+        00000020: 46b4 bcfc 506c e227 2372 e5f5 d7ea 579f  F...Pl.'#r....W.
+        00000030: 6371 5eb5 0eb8 23b5 ca6a 5de5 983a 19e4  cq^...#..j]..:..
+        00000040: e8c3 4320 b4ba a226 cbc1 4138 3a12 32d6  ..C ...&..A8:.2.
+        00000050: fef3 247b 3523 4e90 9682 ac8e eb0c a389  ..${5#N.........
+        00000060: ddd0 6cfc 0187 0e20 7aae b15b 1812 3d33  ..l.... z..[..=3
+        00000070: e1c5 f425 a83a 00b7 4f18 8127 3c4c aefb  ...%.:..O..'<L..
+
+For the buffer with sequence == 1:
+
+.. code-block:: bash
+
+        $ xxd /sys/kernel/debug/visl/bitstream/bitstream1
+        00000000: 0201 d021 49e1 0c40 aa11 1449 14a6 01dc  ...!I..@...I....
+        00000010: 7023 889a c8cd 2cd0 13b4 dab0 e8ca 21fe  p#....,.......!.
+        00000020: c4c8 ab4c 486e 4e2f b0df 96cc c74e 8dde  ...LHnN/.....N..
+        00000030: 8ce7 ee36 d880 4095 4d64 30a0 ff4f 0c5e  ...6..@.Md0..O.^
+        00000040: f16b a6a1 d806 ca2a 0ece a673 7bea 1f37  .k.....*...s{..7
+        00000050: 370f 5bb9 1dc4 ba21 6434 bc53 0173 cba0  7.[....!d4.S.s..
+        00000060: dfe6 bc99 01ea b6e0 346b 92b5 c8de 9f5d  ........4k.....]
+        00000070: e7cc 3484 1769 fef2 a693 a945 2c8b 31da  ..4..i.....E,.1.
+
+And so on.
+
+By default, the files are removed during STREAMOFF. This is to reduce the amount
+of clutter.

Documentation/admin-guide/media/vivid.rst

@@ -392,7 +392,7 @@ Which one is returned depends on the chosen channel, each next valid channel
 will cycle through the possible audio subchannel combinations. This allows
 you to test the various combinations by just switching channels..
 
-Finally, for these inputs the v4l2_timecode struct is filled in in the
+Finally, for these inputs the v4l2_timecode struct is filled in the
 dequeued v4l2_buffer struct.
 
 

Documentation/admin-guide/mm/damon/usage.rst

@@ -88,6 +88,9 @@ comma (","). ::
     │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil
     │ │ │ │ │ │ │ watermarks/metric,interval_us,high,mid,low
     │ │ │ │ │ │ │ stats/nr_tried,sz_tried,nr_applied,sz_applied,qt_exceeds
+    │ │ │ │ │ │ │ tried_regions/
+    │ │ │ │ │ │ │ │ 0/start,end,nr_accesses,age
+    │ │ │ │ │ │ │ │ ...
     │ │ │ │ │ │ ...
     │ │ │ │ ...
     │ │ ...
@@ -125,7 +128,14 @@ in the state.  Writing ``commit`` to the ``state`` file makes kdamond reads the
 user inputs in the sysfs files except ``state`` file again.  Writing
 ``update_schemes_stats`` to ``state`` file updates the contents of stats files
 for each DAMON-based operation scheme of the kdamond.  For details of the
-stats, please refer to :ref:`stats section <sysfs_schemes_stats>`.
+stats, please refer to :ref:`stats section <sysfs_schemes_stats>`.  Writing
+``update_schemes_tried_regions`` to ``state`` file updates the DAMON-based
+operation scheme action tried regions directory for each DAMON-based operation
+scheme of the kdamond.  Writing ``clear_schemes_tried_regions`` to ``state``
+file clears the DAMON-based operating scheme action tried regions directory for
+each DAMON-based operation scheme of the kdamond.  For details of the
+DAMON-based operation scheme action tried regions directory, please refer to
+:ref:tried_regions section <sysfs_schemes_tried_regions>`.
 
 If the state is ``on``, reading ``pid`` shows the pid of the kdamond thread.
 
@@ -166,6 +176,8 @@ You can set and get what type of monitoring operations DAMON will use for the
 context by writing one of the keywords listed in ``avail_operations`` file and
 reading from the ``operations`` file.
 
+.. _sysfs_monitoring_attrs:
+
 contexts/<N>/monitoring_attrs/
 ------------------------------
 
@@ -235,6 +247,9 @@ In each region directory, you will find two files (``start`` and ``end``).  You
 can set and get the start and end addresses of the initial monitoring target
 region by writing to and reading from the files, respectively.
 
+Each region should not overlap with others.  ``end`` of directory ``N`` should
+be equal or smaller than ``start`` of directory ``N+1``.
+
 contexts/<N>/schemes/
 ---------------------
 
@@ -252,8 +267,9 @@ to ``N-1``.  Each directory represents each DAMON-based operation scheme.
 schemes/<N>/
 ------------
 
-In each scheme directory, four directories (``access_pattern``, ``quotas``,
-``watermarks``, and ``stats``) and one file (``action``) exist.
+In each scheme directory, five directories (``access_pattern``, ``quotas``,
+``watermarks``, ``stats``, and ``tried_regions``) and one file (``action``)
+exist.
 
 The ``action`` file is for setting and getting what action you want to apply to
 memory regions having specific access pattern of the interest.  The keywords
@@ -348,6 +364,32 @@ should ask DAMON sysfs interface to updte the content of the files for the
 stats by writing a special keyword, ``update_schemes_stats`` to the relevant
 ``kdamonds/<N>/state`` file.
 
+.. _sysfs_schemes_tried_regions:
+
+schemes/<N>/tried_regions/
+--------------------------
+
+When a special keyword, ``update_schemes_tried_regions``, is written to the
+relevant ``kdamonds/<N>/state`` file, DAMON creates directories named integer
+starting from ``0`` under this directory.  Each directory contains files
+exposing detailed information about each of the memory region that the
+corresponding scheme's ``action`` has tried to be applied under this directory,
+during next :ref:`aggregation interval <sysfs_monitoring_attrs>`.  The
+information includes address range, ``nr_accesses``, , and ``age`` of the
+region.
+
+The directories will be removed when another special keyword,
+``clear_schemes_tried_regions``, is written to the relevant
+``kdamonds/<N>/state`` file.
+
+tried_regions/<N>/
+------------------
+
+In each region directory, you will find four files (``start``, ``end``,
+``nr_accesses``, and ``age``).  Reading the files will show the start and end
+addresses, ``nr_accesses``, and ``age`` of the region that corresponding
+DAMON-based operation scheme ``action`` has tried to be applied.
+
 Example
 ~~~~~~~
 
@@ -465,8 +507,9 @@ regions in case of physical memory monitoring.  Therefore, users should set the
 monitoring target regions by themselves.
 
 In such cases, users can explicitly set the initial monitoring target regions
-as they want, by writing proper values to the ``init_regions`` file.  Each line
-of the input should represent one region in below form.::
+as they want, by writing proper values to the ``init_regions`` file.  The input
+should be a sequence of three integers separated by white spaces that represent
+one region in below form.::
 
     <target idx> <start address> <end address>
 
@@ -481,9 +524,9 @@ ranges, ``20-40`` and ``50-100`` as that of pid 4242, which is the second one
     # cd <debugfs>/damon
     # cat target_ids
     42 4242
-    # echo "0   1       100
-            0   100     200
-            1   20      40
+    # echo "0   1       100 \
+            0   100     200 \
+            1   20      40  \
             1   50      100" > init_regions
 
 Note that this sets the initial monitoring target regions only.  In case of

Documentation/admin-guide/mm/zswap.rst

@@ -14,13 +14,7 @@ for potentially reduced swap I/O.  This trade-off can also result in a
 significant performance improvement if reads from the compressed cache are
 faster than reads from a swap device.
 
-.. note::
-   Zswap is a new feature as of v3.11 and interacts heavily with memory
-   reclaim.  This interaction has not been fully explored on the large set of
-   potential configurations and workloads that exist.  For this reason, zswap
-   is a work in progress and should be considered experimental.
-
-   Some potential benefits:
+Some potential benefits:
 
 * Desktop/laptop users with limited RAM capacities can mitigate the
   performance impact of swapping.

Documentation/admin-guide/perf/hisi-pcie-pmu.rst

@@ -15,10 +15,10 @@ HiSilicon PCIe PMU driver
 The PCIe PMU driver registers a perf PMU with the name of its sicl-id and PCIe
 Core id.::
 
-  /sys/bus/event_source/hisi_pcie<sicl>_<core>
+  /sys/bus/event_source/hisi_pcie<sicl>_core<core>
 
 PMU driver provides description of available events and filter options in sysfs,
-see /sys/bus/event_source/devices/hisi_pcie<sicl>_<core>.
+see /sys/bus/event_source/devices/hisi_pcie<sicl>_core<core>.
 
 The "format" directory describes all formats of the config (events) and config1
 (filter options) fields of the perf_event_attr structure. The "events" directory
@@ -33,13 +33,13 @@ monitored by PMU.
 Example usage of perf::
 
   $# perf list
-  hisi_pcie0_0/rx_mwr_latency/ [kernel PMU event]
-  hisi_pcie0_0/rx_mwr_cnt/ [kernel PMU event]
+  hisi_pcie0_core0/rx_mwr_latency/ [kernel PMU event]
+  hisi_pcie0_core0/rx_mwr_cnt/ [kernel PMU event]
   ------------------------------------------
 
-  $# perf stat -e hisi_pcie0_0/rx_mwr_latency/
-  $# perf stat -e hisi_pcie0_0/rx_mwr_cnt/
-  $# perf stat -g -e hisi_pcie0_0/rx_mwr_latency/ -e hisi_pcie0_0/rx_mwr_cnt/
+  $# perf stat -e hisi_pcie0_core0/rx_mwr_latency/
+  $# perf stat -e hisi_pcie0_core0/rx_mwr_cnt/
+  $# perf stat -g -e hisi_pcie0_core0/rx_mwr_latency/ -e hisi_pcie0_core0/rx_mwr_cnt/
 
 The current driver does not support sampling. So "perf record" is unsupported.
 Also attach to a task is unsupported for PCIe PMU.
@@ -48,59 +48,83 @@ Filter options
 --------------
 
 1. Target filter
-PMU could only monitor the performance of traffic downstream target Root Ports
-or downstream target Endpoint. PCIe PMU driver support "port" and "bdf"
-interfaces for users, and these two interfaces aren't supported at the same
-time.
 
--port
-"port" filter can be used in all PCIe PMU events, target Root Port can be
-selected by configuring the 16-bits-bitmap "port". Multi ports can be selected
-for AP-layer-events, and only one port can be selected for TL/DL-layer-events.
+   PMU could only monitor the performance of traffic downstream target Root
+   Ports or downstream target Endpoint. PCIe PMU driver support "port" and
+   "bdf" interfaces for users, and these two interfaces aren't supported at the
+   same time.
 
-For example, if target Root Port is 0000:00:00.0 (x8 lanes), bit0 of bitmap
-should be set, port=0x1; if target Root Port is 0000:00:04.0 (x4 lanes),
-bit8 is set, port=0x100; if these two Root Ports are both monitored, port=0x101.
+   - port
 
-Example usage of perf::
+     "port" filter can be used in all PCIe PMU events, target Root Port can be
+     selected by configuring the 16-bits-bitmap "port". Multi ports can be
+     selected for AP-layer-events, and only one port can be selected for
+     TL/DL-layer-events.
 
-  $# perf stat -e hisi_pcie0_0/rx_mwr_latency,port=0x1/ sleep 5
+     For example, if target Root Port is 0000:00:00.0 (x8 lanes), bit0 of
+     bitmap should be set, port=0x1; if target Root Port is 0000:00:04.0 (x4
+     lanes), bit8 is set, port=0x100; if these two Root Ports are both
+     monitored, port=0x101.
 
--bdf
+     Example usage of perf::
 
-"bdf" filter can only be used in bandwidth events, target Endpoint is selected
-by configuring BDF to "bdf". Counter only counts the bandwidth of message
-requested by target Endpoint.
+       $# perf stat -e hisi_pcie0_core0/rx_mwr_latency,port=0x1/ sleep 5
 
-For example, "bdf=0x3900" means BDF of target Endpoint is 0000:39:00.0.
+   - bdf
 
-Example usage of perf::
+     "bdf" filter can only be used in bandwidth events, target Endpoint is
+     selected by configuring BDF to "bdf". Counter only counts the bandwidth of
+     message requested by target Endpoint.
+
+     For example, "bdf=0x3900" means BDF of target Endpoint is 0000:39:00.0.
+
+     Example usage of perf::
 
-  $# perf stat -e hisi_pcie0_0/rx_mrd_flux,bdf=0x3900/ sleep 5
+       $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,bdf=0x3900/ sleep 5
 
 2. Trigger filter
-Event statistics start when the first time TLP length is greater/smaller
-than trigger condition. You can set the trigger condition by writing "trig_len",
-and set the trigger mode by writing "trig_mode". This filter can only be used
-in bandwidth events.
 
-For example, "trig_len=4" means trigger condition is 2^4 DW, "trig_mode=0"
-means statistics start when TLP length > trigger condition, "trig_mode=1"
-means start when TLP length < condition.
+   Event statistics start when the first time TLP length is greater/smaller
+   than trigger condition. You can set the trigger condition by writing
+   "trig_len", and set the trigger mode by writing "trig_mode". This filter can
+   only be used in bandwidth events.
 
-Example usage of perf::
+   For example, "trig_len=4" means trigger condition is 2^4 DW, "trig_mode=0"
+   means statistics start when TLP length > trigger condition, "trig_mode=1"
+   means start when TLP length < condition.
+
+   Example usage of perf::
 
-  $# perf stat -e hisi_pcie0_0/rx_mrd_flux,trig_len=0x4,trig_mode=1/ sleep 5
+     $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,trig_len=0x4,trig_mode=1/ sleep 5
 
 3. Threshold filter
-Counter counts when TLP length within the specified range. You can set the
-threshold by writing "thr_len", and set the threshold mode by writing
-"thr_mode". This filter can only be used in bandwidth events.
 
-For example, "thr_len=4" means threshold is 2^4 DW, "thr_mode=0" means
-counter counts when TLP length >= threshold, and "thr_mode=1" means counts
-when TLP length < threshold.
+   Counter counts when TLP length within the specified range. You can set the
+   threshold by writing "thr_len", and set the threshold mode by writing
+   "thr_mode". This filter can only be used in bandwidth events.
 
-Example usage of perf::
+   For example, "thr_len=4" means threshold is 2^4 DW, "thr_mode=0" means
+   counter counts when TLP length >= threshold, and "thr_mode=1" means counts
+   when TLP length < threshold.
+
+   Example usage of perf::
+
+     $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,thr_len=0x4,thr_mode=1/ sleep 5
+
+4. TLP Length filter
+
+   When counting bandwidth, the data can be composed of certain parts of TLP
+   packets. You can specify it through "len_mode":
+
+   - 2'b00: Reserved (Do not use this since the behaviour is undefined)
+   - 2'b01: Bandwidth of TLP payloads
+   - 2'b10: Bandwidth of TLP headers
+   - 2'b11: Bandwidth of both TLP payloads and headers
+
+   For example, "len_mode=2" means only counting the bandwidth of TLP headers
+   and "len_mode=3" means the final bandwidth data is composed of both TLP
+   headers and payloads. Default value if not specified is 2'b11.
+
+   Example usage of perf::
 
-  $# perf stat -e hisi_pcie0_0/rx_mrd_flux,thr_len=0x4,thr_mode=1/ sleep 5
+     $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,len_mode=0x1/ sleep 5

Documentation/admin-guide/perf/index.rst

@@ -19,3 +19,5 @@ Performance monitor support
    arm_dsu_pmu
    thunderx2-pmu
    alibaba_pmu
+   nvidia-pmu
+   meson-ddr-pmu

Documentation/admin-guide/perf/meson-ddr-pmu.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===========================================================
+Amlogic SoC DDR Bandwidth Performance Monitoring Unit (PMU)
+===========================================================
+
+The Amlogic Meson G12 SoC contains a bandwidth monitor inside DRAM controller.
+The monitor includes 4 channels. Each channel can count the request accessing
+DRAM. The channel can count up to 3 AXI port simultaneously. It can be helpful
+to show if the performance bottleneck is on DDR bandwidth.
+
+Currently, this driver supports the following 5 perf events:
+
++ meson_ddr_bw/total_rw_bytes/
++ meson_ddr_bw/chan_1_rw_bytes/
++ meson_ddr_bw/chan_2_rw_bytes/
++ meson_ddr_bw/chan_3_rw_bytes/
++ meson_ddr_bw/chan_4_rw_bytes/
+
+meson_ddr_bw/chan_{1,2,3,4}_rw_bytes/ events are channel-specific events.
+Each channel support filtering, which can let the channel to monitor
+individual IP module in SoC.
+
+Below are DDR access request event filter keywords:
+
++ arm             - from CPU
++ vpu_read1       - from OSD + VPP read
++ gpu             - from 3D GPU
++ pcie            - from PCIe controller
++ hdcp            - from HDCP controller
++ hevc_front      - from HEVC codec front end
++ usb3_0          - from USB3.0 controller
++ hevc_back       - from HEVC codec back end
++ h265enc         - from HEVC encoder
++ vpu_read2       - from DI read
++ vpu_write1      - from VDIN write
++ vpu_write2      - from di write
++ vdec            - from legacy codec video decoder
++ hcodec          - from H264 encoder
++ ge2d            - from ge2d
++ spicc1          - from SPI controller 1
++ usb0            - from USB2.0 controller 0
++ dma             - from system DMA controller 1
++ arb0            - from arb0
++ sd_emmc_b       - from SD eMMC b controller
++ usb1            - from USB2.0 controller 1
++ audio           - from Audio module
++ sd_emmc_c       - from SD eMMC c controller
++ spicc2          - from SPI controller 2
++ ethernet        - from Ethernet controller
+
+
+Examples:
+
+  + Show the total DDR bandwidth per seconds:
+
+    .. code-block:: bash
+
+       perf stat -a -e meson_ddr_bw/total_rw_bytes/ -I 1000 sleep 10
+
+
+  + Show individual DDR bandwidth from CPU and GPU respectively, as well as
+    sum of them:
+
+    .. code-block:: bash
+
+       perf stat -a -e meson_ddr_bw/chan_1_rw_bytes,arm=1/ -I 1000 sleep 10
+       perf stat -a -e meson_ddr_bw/chan_2_rw_bytes,gpu=1/ -I 1000 sleep 10
+       perf stat -a -e meson_ddr_bw/chan_3_rw_bytes,arm=1,gpu=1/ -I 1000 sleep 10
+

Documentation/admin-guide/perf/nvidia-pmu.rst

+=========================================================
+NVIDIA Tegra SoC Uncore Performance Monitoring Unit (PMU)
+=========================================================
+
+The NVIDIA Tegra SoC includes various system PMUs to measure key performance
+metrics like memory bandwidth, latency, and utilization:
+
+* Scalable Coherency Fabric (SCF)
+* NVLink-C2C0
+* NVLink-C2C1
+* CNVLink
+* PCIE
+
+PMU Driver
+----------
+
+The PMUs in this document are based on ARM CoreSight PMU Architecture as
+described in document: ARM IHI 0091. Since this is a standard architecture, the
+PMUs are managed by a common driver "arm-cs-arch-pmu". This driver describes
+the available events and configuration of each PMU in sysfs. Please see the
+sections below to get the sysfs path of each PMU. Like other uncore PMU drivers,
+the driver provides "cpumask" sysfs attribute to show the CPU id used to handle
+the PMU event. There is also "associated_cpus" sysfs attribute, which contains a
+list of CPUs associated with the PMU instance.
+
+.. _SCF_PMU_Section:
+
+SCF PMU
+-------
+
+The SCF PMU monitors system level cache events, CPU traffic, and
+strongly-ordered (SO) PCIE write traffic to local/remote memory. Please see
+:ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section` for more info about the PMU
+traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_sources/devices/nvidia_scf_pmu_<socket-id>.
+
+Example usage:
+
+* Count event id 0x0 in socket 0::
+
+   perf stat -a -e nvidia_scf_pmu_0/event=0x0/
+
+* Count event id 0x0 in socket 1::
+
+   perf stat -a -e nvidia_scf_pmu_1/event=0x0/
+
+NVLink-C2C0 PMU
+--------------------
+
+The NVLink-C2C0 PMU monitors incoming traffic from a GPU/CPU connected with
+NVLink-C2C (Chip-2-Chip) interconnect. The type of traffic captured by this PMU
+varies dependent on the chip configuration:
+
+* NVIDIA Grace Hopper Superchip: Hopper GPU is connected with Grace SoC.
+
+  In this config, the PMU captures GPU ATS translated or EGM traffic from the GPU.
+
+* NVIDIA Grace CPU Superchip: two Grace CPU SoCs are connected.
+
+  In this config, the PMU captures read and relaxed ordered (RO) writes from
+  PCIE device of the remote SoC.
+
+Please see :ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section` for more info about
+the PMU traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_sources/devices/nvidia_nvlink_c2c0_pmu_<socket-id>.
+
+Example usage:
+
+* Count event id 0x0 from the GPU/CPU connected with socket 0::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_0/event=0x0/
+
+* Count event id 0x0 from the GPU/CPU connected with socket 1::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_1/event=0x0/
+
+* Count event id 0x0 from the GPU/CPU connected with socket 2::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_2/event=0x0/
+
+* Count event id 0x0 from the GPU/CPU connected with socket 3::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_3/event=0x0/
+
+NVLink-C2C1 PMU
+-------------------
+
+The NVLink-C2C1 PMU monitors incoming traffic from a GPU connected with
+NVLink-C2C (Chip-2-Chip) interconnect. This PMU captures untranslated GPU
+traffic, in contrast with NvLink-C2C0 PMU that captures ATS translated traffic.
+Please see :ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section` for more info about
+the PMU traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_sources/devices/nvidia_nvlink_c2c1_pmu_<socket-id>.
+
+Example usage:
+
+* Count event id 0x0 from the GPU connected with socket 0::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_0/event=0x0/
+
+* Count event id 0x0 from the GPU connected with socket 1::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_1/event=0x0/
+
+* Count event id 0x0 from the GPU connected with socket 2::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_2/event=0x0/
+
+* Count event id 0x0 from the GPU connected with socket 3::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_3/event=0x0/
+
+CNVLink PMU
+---------------
+
+The CNVLink PMU monitors traffic from GPU and PCIE device on remote sockets
+to local memory. For PCIE traffic, this PMU captures read and relaxed ordered
+(RO) write traffic. Please see :ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section`
+for more info about the PMU traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_sources/devices/nvidia_cnvlink_pmu_<socket-id>.
+
+Each SoC socket can be connected to one or more sockets via CNVLink. The user can
+use "rem_socket" bitmap parameter to select the remote socket(s) to monitor.
+Each bit represents the socket number, e.g. "rem_socket=0xE" corresponds to
+socket 1 to 3.
+/sys/bus/event_sources/devices/nvidia_cnvlink_pmu_<socket-id>/format/rem_socket
+shows the valid bits that can be set in the "rem_socket" parameter.
+
+The PMU can not distinguish the remote traffic initiator, therefore it does not
+provide filter to select the traffic source to monitor. It reports combined
+traffic from remote GPU and PCIE devices.
+
+Example usage:
+
+* Count event id 0x0 for the traffic from remote socket 1, 2, and 3 to socket 0::
+
+   perf stat -a -e nvidia_cnvlink_pmu_0/event=0x0,rem_socket=0xE/
+
+* Count event id 0x0 for the traffic from remote socket 0, 2, and 3 to socket 1::
+
+   perf stat -a -e nvidia_cnvlink_pmu_1/event=0x0,rem_socket=0xD/
+
+* Count event id 0x0 for the traffic from remote socket 0, 1, and 3 to socket 2::
+
+   perf stat -a -e nvidia_cnvlink_pmu_2/event=0x0,rem_socket=0xB/
+
+* Count event id 0x0 for the traffic from remote socket 0, 1, and 2 to socket 3::
+
+   perf stat -a -e nvidia_cnvlink_pmu_3/event=0x0,rem_socket=0x7/
+
+
+PCIE PMU
+------------
+
+The PCIE PMU monitors all read/write traffic from PCIE root ports to
+local/remote memory. Please see :ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section`
+for more info about the PMU traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_sources/devices/nvidia_pcie_pmu_<socket-id>.
+
+Each SoC socket can support multiple root ports. The user can use
+"root_port" bitmap parameter to select the port(s) to monitor, i.e.
+"root_port=0xF" corresponds to root port 0 to 3.
+/sys/bus/event_sources/devices/nvidia_pcie_pmu_<socket-id>/format/root_port
+shows the valid bits that can be set in the "root_port" parameter.
+
+Example usage:
+
+* Count event id 0x0 from root port 0 and 1 of socket 0::
+
+   perf stat -a -e nvidia_pcie_pmu_0/event=0x0,root_port=0x3/
+
+* Count event id 0x0 from root port 0 and 1 of socket 1::
+
+   perf stat -a -e nvidia_pcie_pmu_1/event=0x0,root_port=0x3/
+
+.. _NVIDIA_Uncore_PMU_Traffic_Coverage_Section:
+
+Traffic Coverage
+----------------
+
+The PMU traffic coverage may vary dependent on the chip configuration:
+
+* **NVIDIA Grace Hopper Superchip**: Hopper GPU is connected with Grace SoC.
+
+  Example configuration with two Grace SoCs::
+
+   *********************************          *********************************
+   * SOCKET-A                      *          * SOCKET-B                      *
+   *                               *          *                               *
+   *                     ::::::::  *          *  ::::::::                     *
+   *                     : PCIE :  *          *  : PCIE :                     *
+   *                     ::::::::  *          *  ::::::::                     *
+   *                         |     *          *      |                        *
+   *                         |     *          *      |                        *
+   *  :::::::            ::::::::: *          *  :::::::::            ::::::: *
+   *  :     :            :       : *          *  :       :            :     : *
+   *  : GPU :<--NVLink-->: Grace :<---CNVLink--->: Grace :<--NVLink-->: GPU : *
+   *  :     :    C2C     :  SoC  : *          *  :  SoC  :    C2C     :     : *
+   *  :::::::            ::::::::: *          *  :::::::::            ::::::: *
+   *     |                   |     *          *      |                   |    *
+   *     |                   |     *          *      |                   |    *
+   *  &&&&&&&&           &&&&&&&&  *          *   &&&&&&&&           &&&&&&&& *
+   *  & GMEM &           & CMEM &  *          *   & CMEM &           & GMEM & *
+   *  &&&&&&&&           &&&&&&&&  *          *   &&&&&&&&           &&&&&&&& *
+   *                               *          *                               *
+   *********************************          *********************************
+
+   GMEM = GPU Memory (e.g. HBM)
+   CMEM = CPU Memory (e.g. LPDDR5X)
+
+  |
+  | Following table contains traffic coverage of Grace SoC PMU in socket-A:
+
+  ::
+
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+   |              |                        Source                             |
+   +              +-------+-----------+-----------+-----+----------+----------+
+   | Destination  |       |GPU ATS    |GPU Not-ATS|     | Socket-B | Socket-B |
+   |              |PCI R/W|Translated,|Translated | CPU | CPU/PCIE1| GPU/PCIE2|
+   |              |       |EGM        |           |     |          |          |
+   +==============+=======+===========+===========+=====+==========+==========+
+   | Local        | PCIE  |NVLink-C2C0|NVLink-C2C1| SCF | SCF PMU  | CNVLink  |
+   | SYSRAM/CMEM  | PMU   |PMU        |PMU        | PMU |          | PMU      |
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+   | Local GMEM   | PCIE  |    N/A    |NVLink-C2C1| SCF | SCF PMU  | CNVLink  |
+   |              | PMU   |           |PMU        | PMU |          | PMU      |
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+   | Remote       | PCIE  |NVLink-C2C0|NVLink-C2C1| SCF |          |          |
+   | SYSRAM/CMEM  | PMU   |PMU        |PMU        | PMU |   N/A    |   N/A    |
+   | over CNVLink |       |           |           |     |          |          |
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+   | Remote GMEM  | PCIE  |NVLink-C2C0|NVLink-C2C1| SCF |          |          |
+   | over CNVLink | PMU   |PMU        |PMU        | PMU |   N/A    |   N/A    |
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+
+   PCIE1 traffic represents strongly ordered (SO) writes.
+   PCIE2 traffic represents reads and relaxed ordered (RO) writes.
+
+* **NVIDIA Grace CPU Superchip**: two Grace CPU SoCs are connected.
+
+  Example configuration with two Grace SoCs::
+
+   *******************             *******************
+   * SOCKET-A        *             * SOCKET-B        *
+   *                 *             *                 *
+   *    ::::::::     *             *    ::::::::     *
+   *    : PCIE :     *             *    : PCIE :     *
+   *    ::::::::     *             *    ::::::::     *
+   *        |        *             *        |        *
+   *        |        *             *        |        *
+   *    :::::::::    *             *    :::::::::    *
+   *    :       :    *             *    :       :    *
+   *    : Grace :<--------NVLink------->: Grace :    *
+   *    :  SoC  :    *     C2C     *    :  SoC  :    *
+   *    :::::::::    *             *    :::::::::    *
+   *        |        *             *        |        *
+   *        |        *             *        |        *
+   *     &&&&&&&&    *             *     &&&&&&&&    *
+   *     & CMEM &    *             *     & CMEM &    *
+   *     &&&&&&&&    *             *     &&&&&&&&    *
+   *                 *             *                 *
+   *******************             *******************
+
+   GMEM = GPU Memory (e.g. HBM)
+   CMEM = CPU Memory (e.g. LPDDR5X)
+
+  |
+  | Following table contains traffic coverage of Grace SoC PMU in socket-A:
+
+  ::
+
+   +-----------------+-----------+---------+----------+-------------+
+   |                 |                      Source                  |
+   +                 +-----------+---------+----------+-------------+
+   | Destination     |           |         | Socket-B | Socket-B    |
+   |                 |  PCI R/W  |   CPU   | CPU/PCIE1| PCIE2       |
+   |                 |           |         |          |             |
+   +=================+===========+=========+==========+=============+
+   | Local           |  PCIE PMU | SCF PMU | SCF PMU  | NVLink-C2C0 |
+   | SYSRAM/CMEM     |           |         |          | PMU         |
+   +-----------------+-----------+---------+----------+-------------+
+   | Remote          |           |         |          |             |
+   | SYSRAM/CMEM     |  PCIE PMU | SCF PMU |   N/A    |     N/A     |
+   | over NVLink-C2C |           |         |          |             |
+   +-----------------+-----------+---------+----------+-------------+
+
+   PCIE1 traffic represents strongly ordered (SO) writes.
+   PCIE2 traffic represents reads and relaxed ordered (RO) writes.

Documentation/admin-guide/sysctl/fs.rst

@@ -2,8 +2,6 @@
 Documentation for /proc/sys/fs/
 ===============================
 
-kernel version 2.2.10
-
 Copyright (c) 1998, 1999,  Rik van Riel <riel@nl.linux.org>
 
 Copyright (c) 2009,        Shen Feng<shen@cn.fujitsu.com>
@@ -12,58 +10,40 @@ For general info and legal blurb, please look in intro.rst.
 
 ------------------------------------------------------------------------------
 
-This file contains documentation for the sysctl files in
-/proc/sys/fs/ and is valid for Linux kernel version 2.2.
+This file contains documentation for the sysctl files and directories
+in ``/proc/sys/fs/``.
 
 The files in this directory can be used to tune and monitor
 miscellaneous and general things in the operation of the Linux
-kernel. Since some of the files _can_ be used to screw up your
+kernel. Since some of the files *can* be used to screw up your
 system, it is advisable to read both documentation and source
 before actually making adjustments.
 
 1. /proc/sys/fs
 ===============
 
-Currently, these files are in /proc/sys/fs:
-
-- aio-max-nr
-- aio-nr
-- dentry-state
-- dquot-max
-- dquot-nr
-- file-max
-- file-nr
-- inode-max
-- inode-nr
-- inode-state
-- nr_open
-- overflowuid
-- overflowgid
-- pipe-user-pages-hard
-- pipe-user-pages-soft
-- protected_fifos
-- protected_hardlinks
-- protected_regular
-- protected_symlinks
-- suid_dumpable
-- super-max
-- super-nr
+Currently, these files might (depending on your configuration)
+show up in ``/proc/sys/fs``:
+
+.. contents:: :local:
 
 
 aio-nr & aio-max-nr
 -------------------
 
-aio-nr is the running total of the number of events specified on the
-io_setup system call for all currently active aio contexts.  If aio-nr
-reaches aio-max-nr then io_setup will fail with EAGAIN.  Note that
-raising aio-max-nr does not result in the pre-allocation or re-sizing
-of any kernel data structures.
+``aio-nr`` shows the current system-wide number of asynchronous io
+requests.  ``aio-max-nr`` allows you to change the maximum value
+``aio-nr`` can grow to.  If ``aio-nr`` reaches ``aio-nr-max`` then
+``io_setup`` will fail with ``EAGAIN``.  Note that raising
+``aio-max-nr`` does not result in the
+pre-allocation or re-sizing of any kernel data structures.
 
 
 dentry-state
 ------------
 
-From linux/include/linux/dcache.h::
+This file shows the values in ``struct dentry_stat``, as defined in
+``linux/include/linux/dcache.h``::
 
   struct dentry_stat_t dentry_stat {
         int nr_dentry;
@@ -76,95 +56,84 @@ From linux/include/linux/dcache.h::
 
 Dentries are dynamically allocated and deallocated.
 
-nr_dentry shows the total number of dentries allocated (active
-+ unused). nr_unused shows the number of dentries that are not
+``nr_dentry`` shows the total number of dentries allocated (active
++ unused). ``nr_unused shows`` the number of dentries that are not
 actively used, but are saved in the LRU list for future reuse.
 
-Age_limit is the age in seconds after which dcache entries
-can be reclaimed when memory is short and want_pages is
-nonzero when shrink_dcache_pages() has been called and the
+``age_limit`` is the age in seconds after which dcache entries
+can be reclaimed when memory is short and ``want_pages`` is
+nonzero when ``shrink_dcache_pages()`` has been called and the
 dcache isn't pruned yet.
 
-nr_negative shows the number of unused dentries that are also
+``nr_negative`` shows the number of unused dentries that are also
 negative dentries which do not map to any files. Instead,
 they help speeding up rejection of non-existing files provided
 by the users.
 
 
-dquot-max & dquot-nr
---------------------
-
-The file dquot-max shows the maximum number of cached disk
-quota entries.
-
-The file dquot-nr shows the number of allocated disk quota
-entries and the number of free disk quota entries.
-
-If the number of free cached disk quotas is very low and
-you have some awesome number of simultaneous system users,
-you might want to raise the limit.
-
-
 file-max & file-nr
 ------------------
 
-The value in file-max denotes the maximum number of file-
+The value in ``file-max`` denotes the maximum number of file-
 handles that the Linux kernel will allocate. When you get lots
 of error messages about running out of file handles, you might
 want to increase this limit.
 
 Historically,the kernel was able to allocate file handles
 dynamically, but not to free them again. The three values in
-file-nr denote the number of allocated file handles, the number
+``file-nr`` denote the number of allocated file handles, the number
 of allocated but unused file handles, and the maximum number of
-file handles. Linux 2.6 always reports 0 as the number of free
+file handles. Linux 2.6 and later always reports 0 as the number of free
 file handles -- this is not an error, it just means that the
 number of allocated file handles exactly matches the number of
 used file handles.
 
-Attempts to allocate more file descriptors than file-max are
-reported with printk, look for "VFS: file-max limit <number>
-reached".
+Attempts to allocate more file descriptors than ``file-max`` are
+reported with ``printk``, look for::
 
+  VFS: file-max limit <number> reached
 
-nr_open
--------
-
-This denotes the maximum number of file-handles a process can
-allocate. Default value is 1024*1024 (1048576) which should be
-enough for most machines. Actual limit depends on RLIMIT_NOFILE
-resource limit.
+in the kernel logs.
 
 
-inode-max, inode-nr & inode-state
----------------------------------
+inode-nr & inode-state
+----------------------
 
 As with file handles, the kernel allocates the inode structures
 dynamically, but can't free them yet.
 
-The value in inode-max denotes the maximum number of inode
-handlers. This value should be 3-4 times larger than the value
-in file-max, since stdin, stdout and network sockets also
-need an inode struct to handle them. When you regularly run
-out of inodes, you need to increase this value.
-
-The file inode-nr contains the first two items from
-inode-state, so we'll skip to that file...
+The file ``inode-nr`` contains the first two items from
+``inode-state``, so we'll skip to that file...
 
-Inode-state contains three actual numbers and four dummies.
-The actual numbers are, in order of appearance, nr_inodes,
-nr_free_inodes and preshrink.
+``inode-state`` contains three actual numbers and four dummies.
+The actual numbers are, in order of appearance, ``nr_inodes``,
+``nr_free_inodes`` and ``preshrink``.
 
-Nr_inodes stands for the number of inodes the system has
-allocated, this can be slightly more than inode-max because
-Linux allocates them one pageful at a time.
+``nr_inodes`` stands for the number of inodes the system has
+allocated.
 
-Nr_free_inodes represents the number of free inodes (?) and
-preshrink is nonzero when the nr_inodes > inode-max and the
+``nr_free_inodes`` represents the number of free inodes (?) and
+preshrink is nonzero when the
 system needs to prune the inode list instead of allocating
 more.
 
 
+mount-max
+---------
+
+This denotes the maximum number of mounts that may exist
+in a mount namespace.
+
+
+nr_open
+-------
+
+This denotes the maximum number of file-handles a process can
+allocate. Default value is 1024*1024 (1048576) which should be
+enough for most machines. Actual limit depends on ``RLIMIT_NOFILE``
+resource limit.
+
+
 overflowgid & overflowuid
 -------------------------
 
@@ -192,7 +161,7 @@ pipe-user-pages-soft
 Maximum total number of pages a non-privileged user may allocate for pipes
 before the pipe size gets limited to a single page. Once this limit is reached,
 new pipes will be limited to a single page in size for this user in order to
-limit total memory usage, and trying to increase them using fcntl() will be
+limit total memory usage, and trying to increase them using ``fcntl()`` will be
 denied until usage goes below the limit again. The default value allows to
 allocate up to 1024 pipes at their default size. When set to 0, no limit is
 applied.
@@ -207,7 +176,7 @@ file.
 
 When set to "0", writing to FIFOs is unrestricted.
 
-When set to "1" don't allow O_CREAT open on FIFOs that we don't own
+When set to "1" don't allow ``O_CREAT`` open on FIFOs that we don't own
 in world writable sticky directories, unless they are owned by the
 owner of the directory.
 
@@ -221,7 +190,7 @@ protected_hardlinks
 
 A long-standing class of security issues is the hardlink-based
 time-of-check-time-of-use race, most commonly seen in world-writable
-directories like /tmp. The common method of exploitation of this flaw
+directories like ``/tmp``. The common method of exploitation of this flaw
 is to cross privilege boundaries when following a given hardlink (i.e. a
 root process follows a hardlink created by another user). Additionally,
 on systems without separated partitions, this stops unauthorized users
@@ -239,13 +208,13 @@ This protection is based on the restrictions in Openwall and grsecurity.
 protected_regular
 -----------------
 
-This protection is similar to protected_fifos, but it
+This protection is similar to `protected_fifos`_, but it
 avoids writes to an attacker-controlled regular file, where a program
 expected to create one.
 
 When set to "0", writing to regular files is unrestricted.
 
-When set to "1" don't allow O_CREAT open on regular files that we
+When set to "1" don't allow ``O_CREAT`` open on regular files that we
 don't own in world writable sticky directories, unless they are
 owned by the owner of the directory.
 
@@ -257,7 +226,7 @@ protected_symlinks
 
 A long-standing class of security issues is the symlink-based
 time-of-check-time-of-use race, most commonly seen in world-writable
-directories like /tmp. The common method of exploitation of this flaw
+directories like ``/tmp``. The common method of exploitation of this flaw
 is to cross privilege boundaries when following a given symlink (i.e. a
 root process follows a symlink belonging to another user). For a likely
 incomplete list of hundreds of examples across the years, please see:
@@ -272,23 +241,25 @@ follower match, or when the directory owner matches the symlink's owner.
 This protection is based on the restrictions in Openwall and grsecurity.
 
 
-suid_dumpable:
---------------
+suid_dumpable
+-------------
 
 This value can be used to query and set the core dump mode for setuid
 or otherwise protected/tainted binaries. The modes are
 
 =   ==========  ===============================================================
-0   (default)	traditional behaviour. Any process which has changed
+0   (default)	Traditional behaviour. Any process which has changed
 		privilege levels or is execute only will not be dumped.
-1   (debug)	all processes dump core when possible. The core dump is
+1   (debug)	All processes dump core when possible. The core dump is
 		owned by the current user and no security is applied. This is
 		intended for system debugging situations only.
 		Ptrace is unchecked.
 		This is insecure as it allows regular users to examine the
 		memory contents of privileged processes.
-2   (suidsafe)	any binary which normally would not be dumped is dumped
-		anyway, but only if the "core_pattern" kernel sysctl is set to
+2   (suidsafe)	Any binary which normally would not be dumped is dumped
+		anyway, but only if the ``core_pattern`` kernel sysctl (see
+		:ref:`Documentation/admin-guide/sysctl/kernel.rst <core_pattern>`)
+		is set to
 		either a pipe handler or a fully qualified path. (For more
 		details on this limitation, see CVE-2006-2451.) This mode is
 		appropriate when administrators are attempting to debug
@@ -301,36 +272,11 @@ or otherwise protected/tainted binaries. The modes are
 =   ==========  ===============================================================
 
 
-super-max & super-nr
---------------------
-
-These numbers control the maximum number of superblocks, and
-thus the maximum number of mounted filesystems the kernel
-can have. You only need to increase super-max if you need to
-mount more filesystems than the current value in super-max
-allows you to.
-
-
-aio-nr & aio-max-nr
--------------------
-
-aio-nr shows the current system-wide number of asynchronous io
-requests.  aio-max-nr allows you to change the maximum value
-aio-nr can grow to.
-
-
-mount-max
----------
-
-This denotes the maximum number of mounts that may exist
-in a mount namespace.
-
-
 
 2. /proc/sys/fs/binfmt_misc
 ===========================
 
-Documentation for the files in /proc/sys/fs/binfmt_misc is
+Documentation for the files in ``/proc/sys/fs/binfmt_misc`` is
 in Documentation/admin-guide/binfmt-misc.rst.
 
 
@@ -343,28 +289,32 @@ creation of a  user space  library that  implements  the  POSIX message queues
 API (as noted by the  MSG tag in the  POSIX 1003.1-2001 version  of the System
 Interfaces specification.)
 
-The "mqueue" filesystem contains values for determining/setting  the amount of
-resources used by the file system.
+The "mqueue" filesystem contains values for determining/setting the
+amount of resources used by the file system.
 
-/proc/sys/fs/mqueue/queues_max is a read/write  file for  setting/getting  the
-maximum number of message queues allowed on the system.
+``/proc/sys/fs/mqueue/queues_max`` is a read/write file for
+setting/getting the maximum number of message queues allowed on the
+system.
 
-/proc/sys/fs/mqueue/msg_max  is  a  read/write file  for  setting/getting  the
-maximum number of messages in a queue value.  In fact it is the limiting value
-for another (user) limit which is set in mq_open invocation. This attribute of
-a queue must be less or equal then msg_max.
+``/proc/sys/fs/mqueue/msg_max`` is a read/write file for
+setting/getting the maximum number of messages in a queue value.  In
+fact it is the limiting value for another (user) limit which is set in
+``mq_open`` invocation.  This attribute of a queue must be less than
+or equal to ``msg_max``.
 
-/proc/sys/fs/mqueue/msgsize_max is  a read/write  file for setting/getting the
-maximum  message size value (it is every  message queue's attribute set during
-its creation).
+``/proc/sys/fs/mqueue/msgsize_max`` is a read/write file for
+setting/getting the maximum message size value (it is an attribute of
+every message queue, set during its creation).
 
-/proc/sys/fs/mqueue/msg_default is  a read/write  file for setting/getting the
-default number of messages in a queue value if attr parameter of mq_open(2) is
-NULL. If it exceed msg_max, the default value is initialized msg_max.
+``/proc/sys/fs/mqueue/msg_default`` is a read/write file for
+setting/getting the default number of messages in a queue value if the
+``attr`` parameter of ``mq_open(2)`` is ``NULL``. If it exceeds
+``msg_max``, the default value is initialized to ``msg_max``.
 
-/proc/sys/fs/mqueue/msgsize_default is a read/write file for setting/getting
-the default message size value if attr parameter of mq_open(2) is NULL. If it
-exceed msgsize_max, the default value is initialized msgsize_max.
+``/proc/sys/fs/mqueue/msgsize_default`` is a read/write file for
+setting/getting the default message size value if the ``attr``
+parameter of ``mq_open(2)`` is ``NULL``. If it exceeds
+``msgsize_max``, the default value is initialized to ``msgsize_max``.
 
 4. /proc/sys/fs/epoll - Configuration options for the epoll interface
 =====================================================================
@@ -378,7 +328,7 @@ Every epoll file descriptor can store a number of files to be monitored
 for event readiness. Each one of these monitored files constitutes a "watch".
 This configuration option sets the maximum number of "watches" that are
 allowed for each user.
-Each "watch" costs roughly 90 bytes on a 32bit kernel, and roughly 160 bytes
-on a 64bit one.
-The current default value for  max_user_watches  is the 1/25 (4%) of the
-available low memory, divided for the "watch" cost in bytes.
+Each "watch" costs roughly 90 bytes on a 32-bit kernel, and roughly 160 bytes
+on a 64-bit one.
+The current default value for ``max_user_watches`` is 4% of the
+available low memory, divided by the "watch" cost in bytes.

Documentation/admin-guide/sysctl/kernel.rst

@@ -139,6 +139,8 @@ Highest valid capability of the running kernel.  Exports
 ``CAP_LAST_CAP`` from the kernel.
 
 
+.. _core_pattern:
+
 core_pattern
 ============
 
@@ -174,6 +176,7 @@ core_pattern
 	%f      	executable filename
 	%E		executable path
 	%c		maximum size of core file by resource limit RLIMIT_CORE
+	%C		CPU the task ran on
 	%<OTHER>	both are dropped
 	========	==========================================
 
@@ -433,8 +436,8 @@ ignore-unaligned-usertrap
 
 On architectures where unaligned accesses cause traps, and where this
 feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN``;
-currently, ``arc`` and ``ia64``), controls whether all unaligned traps
-are logged.
+currently, ``arc``, ``ia64`` and ``loongarch``), controls whether all
+unaligned traps are logged.
 
 = =============================================================
 0 Log all unaligned accesses.
@@ -667,6 +670,15 @@ This is the default behavior.
 an oops event is detected.
 
 
+oops_limit
+==========
+
+Number of kernel oopses after which the kernel should panic when
+``panic_on_oops`` is not set. Setting this to 0 disables checking
+the count. Setting this to  1 has the same effect as setting
+``panic_on_oops=1``. The default value is 10000.
+
+
 osrelease, ostype & version
 ===========================
 
@@ -1314,6 +1326,29 @@ watchdog work to be queued by the watchdog timer function, otherwise the NMI
 watchdog — if enabled — can detect a hard lockup condition.
 
 
+split_lock_mitigate (x86 only)
+==============================
+
+On x86, each "split lock" imposes a system-wide performance penalty. On larger
+systems, large numbers of split locks from unprivileged users can result in
+denials of service to well-behaved and potentially more important users.
+
+The kernel mitigates these bad users by detecting split locks and imposing
+penalties: forcing them to wait and only allowing one core to execute split
+locks at a time.
+
+These mitigations can make those bad applications unbearably slow. Setting
+split_lock_mitigate=0 may restore some application performance, but will also
+increase system exposure to denial of service attacks from split lock users.
+
+= ===================================================================
+0 Disable the mitigation mode - just warns the split lock on kernel log
+  and exposes the system to denials of service from the split lockers.
+1 Enable the mitigation mode (this is the default) - penalizes the split
+  lockers with intentional performance degradation.
+= ===================================================================
+
+
 stack_erasing
 =============
 
@@ -1457,8 +1492,8 @@ unaligned-trap
 
 On architectures where unaligned accesses cause traps, and where this
 feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW``; currently,
-``arc`` and ``parisc``), controls whether unaligned traps are caught
-and emulated (instead of failing).
+``arc``, ``parisc`` and ``loongarch``), controls whether unaligned traps
+are caught and emulated (instead of failing).
 
 = ========================================================
 0 Do not emulate unaligned accesses.
@@ -1500,6 +1535,16 @@ entry will default to 2 instead of 0.
 2 Unprivileged calls to ``bpf()`` are disabled
 = =============================================================
 
+
+warn_limit
+==========
+
+Number of kernel warnings after which the kernel should panic when
+``panic_on_warn`` is not set. Setting this to 0 disables checking
+the warning count. Setting this to 1 has the same effect as setting
+``panic_on_warn=1``. The default value is 0.
+
+
 watchdog
 ========
 

Documentation/arm/marvell.rst

@@ -14,18 +14,20 @@ Orion family
 
   Flavors:
         - 88F5082
-        - 88F5181
-        - 88F5181L
-        - 88F5182
+        - 88F5181  a.k.a Orion-1
+        - 88F5181L a.k.a Orion-VoIP
+        - 88F5182  a.k.a Orion-NAS
 
                - Datasheet: https://web.archive.org/web/20210124231420/http://csclub.uwaterloo.ca/~board/ts7800/MV88F5182-datasheet.pdf
                - Programmer's User Guide: https://web.archive.org/web/20210124231536/http://csclub.uwaterloo.ca/~board/ts7800/MV88F5182-opensource-manual.pdf
                - User Manual: https://web.archive.org/web/20210124231631/http://csclub.uwaterloo.ca/~board/ts7800/MV88F5182-usermanual.pdf
                - Functional Errata: https://web.archive.org/web/20210704165540/https://www.digriz.org.uk/ts78xx/88F5182_Functional_Errata.pdf
-        - 88F5281
+        - 88F5281  a.k.a Orion-2
 
                - Datasheet: https://web.archive.org/web/20131028144728/http://www.ocmodshop.com/images/reviews/networking/qnap_ts409u/marvel_88f5281_data_sheet.pdf
-        - 88F6183
+        - 88F6183  a.k.a Orion-1-90
+  Homepage:
+        https://web.archive.org/web/20080607215437/http://www.marvell.com/products/media/index.jsp
   Core:
 	Feroceon 88fr331 (88f51xx) or 88fr531-vd (88f52xx) ARMv5 compatible
   Linux kernel mach directory:

Documentation/arm64/acpi_object_usage.rst

@@ -163,7 +163,7 @@ FPDT   Section 5.2.23 (signature == "FPDT")
 
        **Firmware Performance Data Table**
 
-       Optional, not currently supported.
+       Optional, useful for boot performance profiling.
 
 GTDT   Section 5.2.24 (signature == "GTDT")
 

Documentation/arm64/booting.rst

@@ -121,8 +121,9 @@ Header notes:
 			  to the base of DRAM, since memory below it is not
 			  accessible via the linear mapping
 			1
-			  2MB aligned base may be anywhere in physical
-			  memory
+			  2MB aligned base such that all image_size bytes
+			  counted from the start of the image are within
+			  the 48-bit addressable range of physical memory
   Bits 4-63	Reserved.
   ============= ===============================================================
 
@@ -348,7 +349,7 @@ Before jumping into the kernel, the following conditions must be met:
 
     - HWFGWTR_EL2.nSMPRI_EL1 (bit 54) must be initialised to 0b01.
 
-  For CPUs with the Scalable Matrix Extension FA64 feature (FEAT_SME_FA64)
+  For CPUs with the Scalable Matrix Extension FA64 feature (FEAT_SME_FA64):
 
   - If EL3 is present:
 

Documentation/arm64/elf_hwcaps.rst

@@ -275,6 +275,15 @@ HWCAP2_EBF16
 HWCAP2_SVE_EBF16
     Functionality implied by ID_AA64ZFR0_EL1.BF16 == 0b0010.
 
+HWCAP2_CSSC
+    Functionality implied by ID_AA64ISAR2_EL1.CSSC == 0b0001.
+
+HWCAP2_RPRFM
+    Functionality implied by ID_AA64ISAR2_EL1.RPRFM == 0b0001.
+
+HWCAP2_SVE2P1
+    Functionality implied by ID_AA64ZFR0_EL1.SVEver == 0b0010.
+
 4. Unused AT_HWCAP bits
 -----------------------
 

Documentation/arm64/sve.rst

@@ -52,6 +52,7 @@ model features for SVE is included in Appendix A.
 	HWCAP2_SVEBITPERM
 	HWCAP2_SVESHA3
 	HWCAP2_SVESM4
+	HWCAP2_SVE2P1
 
   This list may be extended over time as the SVE architecture evolves.
 

Documentation/block/inline-encryption.rst

@@ -142,7 +142,7 @@ Therefore, we also introduce *blk-crypto-fallback*, which is an implementation
 of inline encryption using the kernel crypto API.  blk-crypto-fallback is built
 into the block layer, so it works on any block device without any special setup.
 Essentially, when a bio with an encryption context is submitted to a
-request_queue that doesn't support that encryption context, the block layer will
+block_device that doesn't support that encryption context, the block layer will
 handle en/decryption of the bio using blk-crypto-fallback.
 
 For encryption, the data cannot be encrypted in-place, as callers usually rely
@@ -187,7 +187,7 @@ API presented to users of the block layer
 
 ``blk_crypto_config_supported()`` allows users to check ahead of time whether
 inline encryption with particular crypto settings will work on a particular
-request_queue -- either via hardware or via blk-crypto-fallback.  This function
+block_device -- either via hardware or via blk-crypto-fallback.  This function
 takes in a ``struct blk_crypto_config`` which is like blk_crypto_key, but omits
 the actual bytes of the key and instead just contains the algorithm, data unit
 size, etc.  This function can be useful if blk-crypto-fallback is disabled.
@@ -195,7 +195,7 @@ size, etc.  This function can be useful if blk-crypto-fallback is disabled.
 ``blk_crypto_init_key()`` allows users to initialize a blk_crypto_key.
 
 Users must call ``blk_crypto_start_using_key()`` before actually starting to use
-a blk_crypto_key on a request_queue (even if ``blk_crypto_config_supported()``
+a blk_crypto_key on a block_device (even if ``blk_crypto_config_supported()``
 was called earlier).  This is needed to initialize blk-crypto-fallback if it
 will be needed.  This must not be called from the data path, as this may have to
 allocate resources, which may deadlock in that case.
@@ -207,7 +207,7 @@ for en/decryption.  Users don't need to worry about freeing the bio_crypt_ctx
 later, as that happens automatically when the bio is freed or reset.
 
 Finally, when done using inline encryption with a blk_crypto_key on a
-request_queue, users must call ``blk_crypto_evict_key()``.  This ensures that
+block_device, users must call ``blk_crypto_evict_key()``.  This ensures that
 the key is evicted from all keyslots it may be programmed into and unlinked from
 any kernel data structures it may be linked into.
 
@@ -221,9 +221,9 @@ as follows:
 5. ``blk_crypto_evict_key()`` (after all I/O has completed)
 6. Zeroize the blk_crypto_key (this has no dedicated function)
 
-If a blk_crypto_key is being used on multiple request_queues, then
+If a blk_crypto_key is being used on multiple block_devices, then
 ``blk_crypto_config_supported()`` (if used), ``blk_crypto_start_using_key()``,
-and ``blk_crypto_evict_key()`` must be called on each request_queue.
+and ``blk_crypto_evict_key()`` must be called on each block_device.
 
 API presented to device drivers
 ===============================

Documentation/bpf/bpf_design_QA.rst

@@ -298,3 +298,48 @@ A: NO.
 
 The BTF_ID macro does not cause a function to become part of the ABI
 any more than does the EXPORT_SYMBOL_GPL macro.
+
+Q: What is the compatibility story for special BPF types in map values?
+-----------------------------------------------------------------------
+Q: Users are allowed to embed bpf_spin_lock, bpf_timer fields in their BPF map
+values (when using BTF support for BPF maps). This allows to use helpers for
+such objects on these fields inside map values. Users are also allowed to embed
+pointers to some kernel types (with __kptr and __kptr_ref BTF tags). Will the
+kernel preserve backwards compatibility for these features?
+
+A: It depends. For bpf_spin_lock, bpf_timer: YES, for kptr and everything else:
+NO, but see below.
+
+For struct types that have been added already, like bpf_spin_lock and bpf_timer,
+the kernel will preserve backwards compatibility, as they are part of UAPI.
+
+For kptrs, they are also part of UAPI, but only with respect to the kptr
+mechanism. The types that you can use with a __kptr and __kptr_ref tagged
+pointer in your struct are NOT part of the UAPI contract. The supported types can
+and will change across kernel releases. However, operations like accessing kptr
+fields and bpf_kptr_xchg() helper will continue to be supported across kernel
+releases for the supported types.
+
+For any other supported struct type, unless explicitly stated in this document
+and added to bpf.h UAPI header, such types can and will arbitrarily change their
+size, type, and alignment, or any other user visible API or ABI detail across
+kernel releases. The users must adapt their BPF programs to the new changes and
+update them to make sure their programs continue to work correctly.
+
+NOTE: BPF subsystem specially reserves the 'bpf\_' prefix for type names, in
+order to introduce more special fields in the future. Hence, user programs must
+avoid defining types with 'bpf\_' prefix to not be broken in future releases.
+In other words, no backwards compatibility is guaranteed if one using a type
+in BTF with 'bpf\_' prefix.
+
+Q: What is the compatibility story for special BPF types in allocated objects?
+------------------------------------------------------------------------------
+Q: Same as above, but for allocated objects (i.e. objects allocated using
+bpf_obj_new for user defined types). Will the kernel preserve backwards
+compatibility for these features?
+
+A: NO.
+
+Unlike map value types, there are no stability guarantees for this case. The
+whole API to work with allocated objects and any support for special fields
+inside them is unstable (since it is exposed through kfuncs).

Documentation/bpf/bpf_devel_QA.rst

@@ -44,6 +44,33 @@ is a guarantee that the reported issue will be overlooked.**
 Submitting patches
 ==================
 
+Q: How do I run BPF CI on my changes before sending them out for review?
+------------------------------------------------------------------------
+A: BPF CI is GitHub based and hosted at https://github.com/kernel-patches/bpf.
+While GitHub also provides a CLI that can be used to accomplish the same
+results, here we focus on the UI based workflow.
+
+The following steps lay out how to start a CI run for your patches:
+
+- Create a fork of the aforementioned repository in your own account (one time
+  action)
+
+- Clone the fork locally, check out a new branch tracking either the bpf-next
+  or bpf branch, and apply your to-be-tested patches on top of it
+
+- Push the local branch to your fork and create a pull request against
+  kernel-patches/bpf's bpf-next_base or bpf_base branch, respectively
+
+Shortly after the pull request has been created, the CI workflow will run. Note
+that capacity is shared with patches submitted upstream being checked and so
+depending on utilization the run can take a while to finish.
+
+Note furthermore that both base branches (bpf-next_base and bpf_base) will be
+updated as patches are pushed to the respective upstream branches they track. As
+such, your patch set will automatically (be attempted to) be rebased as well.
+This behavior can result in a CI run being aborted and restarted with the new
+base line.
+
 Q: To which mailing list do I need to submit my BPF patches?
 ------------------------------------------------------------
 A: Please submit your BPF patches to the bpf kernel mailing list:

Documentation/bpf/btf.rst

@@ -1062,4 +1062,9 @@ format.::
 7. Testing
 ==========
 
-Kernel bpf selftest `test_btf.c` provides extensive set of BTF-related tests.
+The kernel BPF selftest `tools/testing/selftests/bpf/prog_tests/btf.c`_
+provides an extensive set of BTF-related tests.
+
+.. Links
+.. _tools/testing/selftests/bpf/prog_tests/btf.c:
+   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/testing/selftests/bpf/prog_tests/btf.c

Documentation/bpf/index.rst

@@ -24,11 +24,13 @@ that goes into great technical depth about the BPF Architecture.
    maps
    bpf_prog_run
    classic_vs_extended.rst
+   bpf_iterators
    bpf_licensing
    test_debug
    clang-notes
    linux-notes
    other
+   redirect
 
 .. only::  subproject and html
 

Documentation/bpf/instruction-set.rst

@@ -122,11 +122,11 @@ BPF_END   0xd0   byte swap operations (see `Byte swap instructions`_ below)
 
 ``BPF_XOR | BPF_K | BPF_ALU`` means::
 
-  src_reg = (u32) src_reg ^ (u32) imm32
+  dst_reg = (u32) dst_reg ^ (u32) imm32
 
 ``BPF_XOR | BPF_K | BPF_ALU64`` means::
 
-  src_reg = src_reg ^ imm32
+  dst_reg = dst_reg ^ imm32
 
 
 Byte swap instructions

Documentation/bpf/libbpf/index.rst

 .. SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
 
+.. _libbpf:
+
 libbpf
 ======
 
@@ -7,6 +9,7 @@ libbpf
    :maxdepth: 1
 
    API Documentation <https://libbpf.readthedocs.io/en/latest/api.html>
+   program_types
    libbpf_naming_convention
    libbpf_build
 

Documentation/bpf/programs.rst

@@ -7,3 +7,6 @@ Program Types
    :glob:
 
    prog_*
+
+For a list of all program types, see :ref:`program_types_and_elf` in
+the :ref:`libbpf` documentation.

Documentation/core-api/local_ops.rst

@@ -191,7 +191,7 @@ Here is a sample module which implements a basic per cpu counter using
 
     static void __exit test_exit(void)
     {
-            del_timer_sync(&test_timer);
+            timer_shutdown_sync(&test_timer);
     }
 
     module_init(test_init);