The cpufreq hook should be called whenever the root cfs_rq
utilization changes so update_cfs_rq_load_avg() is a better
place for it. The current location is not invoked in the
enqueue_entity() or update_blocked_averages() paths.
Suggested-by: NVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: NSteve Muckle <smuckle@linaro.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <Juri.Lelli@arm.com>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1458606068-7476-1-git-send-email-smuckle@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

When asymmetric packing is set in the sched_domain and target CPU is
busy, update_sd_pick_busiest() may not select the busiest runqueue.
When target CPU is busy, find_busiest_group() will ignore checks for
asym packing and may continue to load balance using the currently
selected not-the-busiest runqueue as source runqueue.
Selecting the busiest runqueue as source when the target CPU is busy,
should result in achieving much better load balance.

Also when target CPU is not busy and asymmetric packing is set in sd,
select higher CPU as source CPU for load balancing.

While doing this change, move the check to see if target CPU is busy
into check_asym_packing().

The extent of performance benefit from this change decreases with the
increasing load. However there is benefit in undercommit as well as
overcommit conditions.

1. Record per second ebizzy (32 threads) on a 64 CPU power 7 box. (5 iterations)
4.6.0-rc2
	Testcase:         Min         Max         Avg      StdDev
	  ebizzy:  5223767.00 10368236.00  7946971.00  1753094.76

4.6.0-rc2+asym-changes
	Testcase:         Min         Max         Avg      StdDev     %Change
	  ebizzy:  8617191.00 13872356.00 11383980.00  1783400.89     +24.78%

2. Record per second ebizzy (64 threads) on a 64 CPU power 7 box. (5 iterations)
4.6.0-rc2
	Testcase:         Min         Max         Avg      StdDev
	  ebizzy:  6497666.00 18399783.00 10818093.20  4051452.08

4.6.0-rc2+asym-changes
	Testcase:         Min         Max         Avg      StdDev     %Change
	  ebizzy:  7567365.00 19456937.00 11674063.60  4295407.48      +4.40%

3. Record per second ebizzy (128 threads) on a 64 CPU power 7 box. (5 iterations)
4.6.0-rc2
	Testcase:         Min         Max         Avg      StdDev
	  ebizzy: 37073983.00 40341911.00 38776241.80  1259766.82

4.6.0-rc2+asym-changes
	Testcase:         Min         Max         Avg      StdDev     %Change
	  ebizzy: 38030399.00 41333378.00 39827404.40  1255001.86      +2.54%
Signed-off-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1459948660-16073-1-git-send-email-srikar@linux.vnet.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NIngo Molnar <mingo@kernel.org>

Now that local_clock() is explicitly inlined in sched.h, taking its
pointer would uninline it in the compilation unit where it's done,
making (among other things) comparing pointers to this function
produce different results in different compilation units.

Case in point, x86 perf core's user page updating function compares
event's clock against &local_clock to see if it needs to set zero
time offset related bits in the page.

This patch fixes the latter by looking at the "use_clockid" event
attribute instead, to determine whether local clock is used. Fixing
the uninlined local_clock() in perf core is left as an exercise for
the author of the prior work.
Signed-off-by: NAlexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: eranian@google.com
Cc: vince@deater.net
Fixes: http://lkml.kernel.org/r/1459541050-13654-1-git-send-email-daniel.lezcano@linaro.org
Link: http://lkml.kernel.org/r/1460635189-2320-1-git-send-email-alexander.shishkin@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Pull device mapper fix from Mike Snitzer:
 "Fix for earlier 4.6-rc4 stable@ commit that introduced improper use of
  write lock in cmd_read_lock() -- due to cut-n-paste gone awry (and
  sparse didn't catch it)"

* tag 'dm-4.6-fix-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm cache metadata: fix cmd_read_lock() acquiring write lock

Commit 9567366f ("dm cache metadata: fix READ_LOCK macros and
cleanup WRITE_LOCK macros") uses down_write() instead of down_read() in
cmd_read_lock(), yet up_read() is used to release the lock in
READ_UNLOCK().  Fix it.

Fixes: 9567366f ("dm cache metadata: fix READ_LOCK macros and cleanup WRITE_LOCK macros")
Cc: stable@vger.kernel.org
Signed-off-by: NAhmed Samy <f.fallen45@gmail.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Pull char/misc fixes from Greg KH:
 "Here are some small char/misc driver fixes for 4.6-rc4.  Full details
  are in the shortlog, nothing major here.

  These have all been in linux-next for a while with no reported issues"

* tag 'char-misc-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  lkdtm: do not leak free page on kmalloc failure
  lkdtm: fix memory leak of base
  lkdtm: fix memory leak of val
  extcon: palmas: Drop stray IRQF_EARLY_RESUME flag

Pull misc fixes from Greg KH:
 "Here are three small fixes for 4.6-rc4.

  Two fix up some lz4 issues with big endian systems, and the remaining
  one resolves a minor debugfs issue that was reported.

  All have been in linux-next with no reported issues"

* tag 'driver-core-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  lib: lz4: cleanup unaligned access efficiency detection
  lib: lz4: fixed zram with lz4 on big endian machines
  debugfs: Make automount point inodes permanently empty

Pull USB driver fixes from Greg KH:
 "Here are some small USB fixes for 4.6-rc4.

  Mostly xhci fixes for reported issues, a UAS bug that has hit a number
  of people, including stable tree users, and a few other minor things.

  All have been in linux-next for a while with no reported issues"

* tag 'usb-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: hcd: out of bounds access in for_each_companion
  USB: uas: Add a new NO_REPORT_LUNS quirk
  USB: uas: Limit qdepth at the scsi-host level
  doc: usb: Fix typo in gadget_multi documentation
  usb: host: xhci-plat: Make enum xhci_plat_type start at a non zero value
  xhci: fix 10 second timeout on removal of PCI hotpluggable xhci controllers
  usb: xhci: fix wild pointers in xhci_mem_cleanup
  usb: host: xhci-plat: fix cannot work if R-Car Gen2/3 run on above 4GB phys
  usb: host: xhci: add a new quirk XHCI_NO_64BIT_SUPPORT
  xhci: resume USB 3 roothub first
  usb: xhci: applying XHCI_PME_STUCK_QUIRK to Intel BXT B0 host
  cdc-acm: fix crash if flushed with nothing buffered

Pull dmaengine fixes from Vinod Koul:
 "This time we have some odd fixes in hsu, edma, omap and xilinx.

  Usual fixes and nothing special"

* tag 'dmaengine-fix-4.6-rc4' of git://git.infradead.org/users/vkoul/slave-dma:
  dmaengine: dw: fix master selection
  dmaengine: edma: special case slot limit workaround
  dmaengine: edma: Remove dynamic TPTC power management feature
  dmaengine: vdma: don't crash when bad channel is requested
  dmaengine: omap-dma: Do not suppress interrupts for memcpy
  dmaengine: omap-dma: Fix polled channel completion detection and handling
  dmaengine: hsu: correct use of channel status register
  dmaengine: hsu: correct residue calculation of active descriptor
  dmaengine: hsu: set HSU_CH_MTSR to memory width

Pull locking fixlet from Ingo Molnar:
 "Fixes a build warning on certain Kconfig combinations"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Fix print_collision() unused warning

Pull EFI fix from Ingo Molnar:
 "An arm64 boot crash fix"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/arm64: Don't apply MEMBLOCK_NOMAP to UEFI memory map mapping

Pull block fixes from Jens Axboe:
 "A few fixes for the current series. This contains:

   - Two fixes for NVMe:

     One fixes a reset race that can be triggered by repeated
     insert/removal of the module.

     The other fixes an issue on some platforms, where we get probe
     timeouts since legacy interrupts isn't working.  This used not to
     be a problem since we had the worker thread poll for completions,
     but since that was killed off, it means those poor souls can't
     successfully probe their NVMe device.  Use a proper IRQ check and
     probe (msi-x -> msi ->legacy), like most other drivers to work
     around this.  Both from Keith.

   - A loop corruption issue with offset in iters, from Ming Lei.

   - A fix for not having the partition stat per cpu ref count
     initialized before sending out the KOBJ_ADD, which could cause user
     space to access the counter prior to initialization.  Also from
     Ming Lei.

   - A fix for using the wrong congestion state, from Kaixu Xia"

* 'for-linus' of git://git.kernel.dk/linux-block:
  block: loop: fix filesystem corruption in case of aio/dio
  NVMe: Always use MSI/MSI-x interrupts
  NVMe: Fix reset/remove race
  writeback: fix the wrong congested state variable definition
  block: partition: initialize percpuref before sending out KOBJ_ADD

Pull libnvdimm fixes from Ross Zwisler:
 "Two fixes:

   - Fix memcpy_from_pmem() to fallback to memcpy() for architectures
     where CONFIG_ARCH_HAS_PMEM_API=n.

   - Add a comment explaining why we write data twice when clearing
     poison in pmem_do_bvec().

  This has passed a boot test on an X86_32 config, which was the
  architecture where issue #1 above was first noticed"

Dan Williams adds:
 "We're giving this multi-maintainer setup a shot, so expect libnvdimm
  pull requests from either Ross or I going forward"

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  libnvdimm, pmem: clarify the write+clear_poison+write flow
  pmem: fix BUG() error in pmem.h:48 on X86_32

Pull MTD fix from Brian Norris:
 "One MTD fix for v4.6-rc4:

  In the v4.4 cycle, we relaxed the requirement for assigning
  mtd->owner, but we didn't remove this error case.  It's hit only
  by drivers that are both:

   (a) using nand_scan() directly
  and
   (b) built as modules

  We haven't seen explicit complaints about this (most use cases don't
  fit one or both of the above), but we should definitely not be
  BUG()'ing here"

* tag 'for-linus-20160415' of git://git.infradead.org/linux-mtd:
  mtd: nand: Drop mtd.owner requirement in nand_scan

Pull MMC fixes from Ulf Hansson:
 "Here are a couple of mmc fixes intended for v4.6 rc4.

  Regarding the fix for the regression about mmcblk device indexes.  The
  approach taken to solve the problem seems to be good enough.  There
  were some discussions around the solution, but it seems like people
  were happy about it in the end.

  MMC core:
   - Restore similar old behaviour when assigning mmcblk device indexes

  MMC host:
   - tegra: Disable UHS-I modes for Tegra124 to fix regression"

* tag 'mmc-v4.6-rc3' of git://git.linaro.org/people/ulf.hansson/mmc:
  mmc: tegra: Disable UHS-I modes for Tegra124
  mmc: block: Use the mmc host device index as the mmcblk device index

Pull drm fixes from Dave Airlie:
 "This contains fixes for exynos, amdgpu, radeon, i915 and qxl.

  It also contains some fixes to the core drm edid parser.

  qxl:
   - fix for a cursor hotspot issue

  radeon:
   - some MST fixes that I've been running locally and make my monitor a
     bit happier

  exynos:
   - fix some regressions and build fixes

  amdgpu:
   - a couple of small fixes

  i915:
   - two DP MST fixes and a couple of other regression fixes

  Nothing too out of the ordinary or surprising at this point"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/exynos: Use VIDEO_SAMSUNG_S5P_G2D=n as G2D Kconfig dependency
  drm/exynos: fix a warning message
  drm/exynos: mic: fix an error code
  drm/exynos: fimd: fix broken dp_clock control
  drm/exynos: build fbdev code conditionally
  drm/exynos: fix adjusted_mode pointer in exynos_plane_mode_set
  drm/exynos: fix error handling in exynos_drm_subdrv_open
  drm/amd/amdgpu: fix irq domain remove for tonga ih
  drm/i915: fix deadlock on lid open
  drm/radeon: use helper for mst connector dpms.
  drm/radeon/mst: port some MST setup code from DAL.
  drm/amdgpu: add invisible pin size statistic
  drm/edid: Fix DMT 1024x768@43Hz (interlaced) timings
  drm/i915: Exit cherryview_irq_handler() after one pass
  drm/i915: Call intel_dp_mst_resume() before resuming displays
  drm/i915: Fix race condition in intel_dp_destroy_mst_connector()
  drm/edid: Fix parsing of EDID 1.4 Established Timings III descriptor
  drm/edid: Fix EDID Established Timings I and II
  drm/qxl: fix cursor position with non-zero hotspot

Pull parisc ftrace fixes from Helge Deller:
 "This is (most likely) the last pull request for v4.6 for the parisc
  architecture.

  It fixes the FTRACE feature for parisc, which is horribly broken since
   quite some time and doesn't even compile.  This patch just fixes the
  bare minimum (it actually removes more lines than it adds), so that
  the function tracer works again on 32- and 64bit kernels.

  I've queued up additional patches on top of this patch which e.g. add
  the syscall tracer, but those have to wait for the merge window for
  v4.7."

* 'parisc-4.6-4' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Fix ftrace function tracer

The ACPI specification does not specify the state of data after a clear
poison operation.  Potential future libnvdimm bus implementations for
other architectures also might not specify or disagree on the state of
data after clear poison.  Clarify why we write twice.
Reported-by: NJeff Moyer <jmoyer@redhat.com>
Reported-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NJeff Moyer <jmoyer@redhat.com>
Reviewed-by: NVishal Verma <vishal.l.verma@intel.com>

Starting from commit e36f6204(block: split bios to max possible length),
block core starts to split bio in the middle of bvec.

Unfortunately loop dio/aio doesn't consider this situation, and
always treat 'iter.iov_offset' as zero. Then filesystem corruption
is observed.

This patch figures out the offset of the base bvevc via
'bio->bi_iter.bi_bvec_done' and fixes the issue by passing the offset
to iov iterator.

Fixes: e36f6204 (block: split bios to max possible length)
Cc: Keith Busch <keith.busch@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org (4.5)
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Pull x86 fixes from Ingo Molnar:
 "Misc fixes: a binutils fix, an lguest fix, an mcelog fix and a missing
  documentation fix"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Avoid using object after free in genpool
  lguest, x86/entry/32: Fix handling of guest syscalls using interrupt gates
  x86/build: Build compressed x86 kernels as PIE
  x86/mm/pkeys: Add missing Documentation

Pull mm gup cleanup from Ingo Molnar:
 "This removes the ugly get-user-pages API hack, now that all upstream
  code has been migrated to it"

("ugly" is putting it mildly. But it worked.. - Linus)

* 'mm-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  mm/gup: Remove the macro overload API migration helpers from the get_user*() APIs

Pull device mapper fixes from Mike Snitzer:

 - fix a 4.6-rc1 bio-based DM 'struct dm_target_io' leak in an error
   path

 - stable@ fix for DM cache metadata's READ_LOCK macros that were
   incorrectly returning error if the block manager was in read-only
   mode; also cleanup multi-statement macros to use do {} while(0)

* tag 'dm-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm cache metadata: fix READ_LOCK macros and cleanup WRITE_LOCK macros
  dm: fix dm_target_io leak if clone_bio() returns an error

Merge tag 'pwm/for-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm

Pull pwm fix from Thierry Reding:
 "A single one-line fix to turn the regmap cache from an RB-tree to a
  flat cache to avoid lockdep and abort issues"

* tag 'pwm/for-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
  pwm: fsl-ftm: Use flat regmap cache

Pull sound fixes from Takashi Iwai:
 "We've had a very calm development cycle, so far.  Here are the few
  fixes for HD-audio and USB-audio, all of which are small and easy"

* tag 'sound-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Fix inconsistent monitor_present state until repoll
  ALSA: hda - Fix regression of monitor_present flag in eld proc file
  ALSA: usb-audio: Skip volume controls triggers hangup on Dell USB Dock
  ALSA: hda/realtek - Enable the ALC292 dock fixup on the Thinkpad T460s
  ALSA: sscape: Use correct format identifier for size_t
  ALSA: usb-audio: Add a quirk for Plantronics BT300
  ALSA: usb-audio: Add a sample rate quirk for Phoenix Audio TMX320
  ALSA: hda - Bind with i915 only when Intel graphics is present

Pull mailbox fixes from Jussi Brar:
 "Misc fixes:

  mailbox-test driver:
   - prevent memory leak and another cosmetic change

  mailbox:
   - change the returned error code

  Xgene driver:
   - return -ENOMEM instead of PTR_ERR for failed devm_kzalloc"

* 'mailbox-devel' of git://git.linaro.org/landing-teams/working/fujitsu/integration:
  mailbox: Stop using ENOSYS for anything other than unimplemented syscalls
  mailbox: mailbox-test: Prevent memory leak
  mailbox: mailbox-test: Use more consistent format for calling copy_from_user()
  mailbox: xgene-slimpro: Fix wrong test for devm_kzalloc

Pull f2fs/fscrypto fixes from Jaegeuk Kim:
 "In addition to f2fs/fscrypto fixes, I've added one patch which
  prevents RCU mode lookup in d_revalidate, as Al mentioned.

  These patches fix f2fs and fscrypto based on -rc3 bug fixes in ext4
  crypto, which have not yet been fully propagated as follows.

   - use of dget_parent and file_dentry to avoid crashes
   - disallow RCU-mode lookup in d_invalidate
   - disallow -ENOMEM in the core data encryption path"

* tag 'for-linus-4.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
  ext4/fscrypto: avoid RCU lookup in d_revalidate
  fscrypto: don't let data integrity writebacks fail with ENOMEM
  f2fs: use dget_parent and file_dentry in f2fs_file_open
  fscrypto: use dget_parent() in fscrypt_d_revalidate()

Pull crypto fixes from Herbert Xu:
 "This fixes an NFS regression caused by the skcipher/hash conversion in
  sunrpc.  It also fixes a build problem in certain configurations with
  bcm63xx"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  hwrng: bcm63xx - fix device tree compilation
  sunrpc: Fix skcipher/shash conversion

Pull keys bugfixes from James Morris:
 "Two bugfixes for Keys related code"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  ASN.1: fix open failure check on headername
  assoc_array: don't call compare_object() on a node

The READ_LOCK macro was incorrectly returning -EINVAL if
dm_bm_is_read_only() was true -- it will always be true once the cache
metadata transitions to read-only by dm_cache_metadata_set_read_only().

Wrap READ_LOCK and WRITE_LOCK multi-statement macros in do {} while(0).
Also, all accesses of the 'cmd' argument passed to these related macros
are now encapsulated in parenthesis.

A follow-up patch can be developed to eliminate the use of macros in
favor of pure C code.  Avoiding that now given that this needs to apply
to stable@.
Reported-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Fixes: d14fcf3d ("dm cache: make sure every metadata function checks fail_io")
Cc: stable@vger.kernel.org

Multiple users have reported device initialization failure due the driver
not receiving legacy PCI interrupts. This is not unique to any particular
controller, but has been observed on multiple platforms.

There have been no issues reported or observed when with message signaled
interrupts, so this patch attempts to use MSI-x during initialization,
falling back to MSI. If that fails, legacy would become the default.

The setup_io_queues error handling had to change as a result: the admin
queue's msix_entry used to be initialized to the legacy IRQ. The case
where nr_io_queues is 0 would fail request_irq when setting up the admin
queue's interrupt since re-enabling MSI-x fails with 0 vectors, leaving
the admin queue's msix_entry invalid. Instead, return success immediately.
Reported-by: NTim Muhlemmer <muhlemmer@gmail.com>
Reported-by: NJon Derrick <jonathan.derrick@intel.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

In commit c4004b02 ("x86: remove the kernel code/data/bss resources
from /proc/iomem") I was hoping to remove the phyiscal kernel address
data from /proc/iomem entirely, but that had to be reverted because some
system programs actually use it.

This limits all the detailed resource information to properly
credentialed users instead.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The PCI config access checked the file capabilities correctly, but used
the itnernal security capability check rather than the helper function
that is actually meant for that.

The security_capable() has unusual return values and is not meant to be
used elsewhere (the only other use is in the capability checking
functions that we actually intend people to use, and this odd PCI usage
really stood out when looking around the capability code.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A lot of seqfile users seem to be using things like %pK that uses the
credentials of the current process, but that is actually completely
wrong for filesystem interfaces.

The unix semantics for permission checking files is to check permissions
at _open_ time, not at read or write time, and that is not just a small
detail: passing off stdin/stdout/stderr to a suid application and making
the actual IO happen in privileged context is a classic exploit
technique.

So if we want to be able to look at permissions at read time, we need to
use the file open credentials, not the current ones.  Normal file
accesses can just use "f_cred" (or any of the helper functions that do
that, like file_ns_capable()), but the seqfile interfaces do not have
any such options.

It turns out that seq_file _does_ save away the user_ns information of
the file, though.  Since user_ns is just part of the full credential
information, replace that special case with saving off the cred pointer
instead, and suddenly seq_file has all the permission information it
needs.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This reverts commit c4004b02.

Sadly, my hope that nobody would actually use the special kernel entries
in /proc/iomem were dashed by kexec.  Which reads /proc/iomem explicitly
to find the kernel base address.  Nasty.

Anyway, that means we can't do the sane and simple thing and just remove
the entries, and we'll instead have to mask them out based on permissions.
Reported-by: NZhengyu Zhang <zhezhang@redhat.com>
Reported-by: NDave Young <dyoung@redhat.com>
Reported-by: NFreeman Zhang <freeman.zhang1992@gmail.com>
Reported-by: NEmrah Demir <ed@abdsec.com>
Reported-by: NBaoquan He <bhe@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>