[Why]
Prop are created at boot stage, and not allowed to create new prop
after device registration.

[How]
Reuse the connector property from SST if exist.
Signed-off-by: NJerry (Fangzhi) Zuo <Jerry.Zuo@amd.com>
Reviewed-by: NHersen Wu <hersenxs.wu@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Replace dev_warn() with dev_info() and note that they are
optional to avoid confusing users.

The RAS TAs only exist on server boards and the HDCP and DTM
TAs only exist on client boards.  They are optional either way.
Acked-by: NNirmoy Das <nirmoy.das@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

prefix RAS error related dmesg print with pci device info
Reviewed-by: NHawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: NJohn Clements <john.clements@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

upon receiving uncorrectable error, query every GPU node for ras errors
Reviewed-by: NHawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: NJohn Clements <john.clements@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Incorrect CG sequence will cause gfx timedout,
if we keep switching power profile mode
(enter profile mod such as PEAK will disable CG,
exit profile mode EXIT will enable CG)
when run Vulkan test case(case used for test: vkexample).
Signed-off-by: NChengming Gui <Jack.Gui@amd.com>
Reviewed-by: NKenneth Feng <kenneth.feng@amd.com>
Acked-by: NEvan Quan <evan.quan@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

On ARCTURUS and RENOIR, powerplay is not supported yet.
When plug in or unplug power jack, ACPI event will issue.
Then kernel NULL pointer BUG will be triggered.
Check for NULL pointers before calling.
Signed-off-by: NAaron Ma <aaron.ma@canonical.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Change SH_MEM_CONFIG Alignment mode to Automatic, as:
1)OGL fn_amd_compute_shader will failed with unaligned mode.
2)The default alignment mode was defined to automatic on gfx10
specification.
Signed-off-by: NLikun Gao <Likun.Gao@amd.com>
Reviewed-by: NHawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

hwmgr->pm_en is initialized at hwmgr_hw_init.
during amdgpu_device_init, there is amdgpu_asic_reset that calls to
pp_get_asic_baco_capability, while hwmgr->pm_en has not yet been initialized.

so avoid using pm_en in pp_get_asic_baco_capability.
Reviewed-by: NEmily Deng <Emily.Deng@amd.com>
Signed-off-by: NTiecheng Zhou <Tiecheng.Zhou@amd.com>
Signed-off-by: NYintian Tao <yttao@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

As the pmfw hasn't exported the interface of SMU feature
mask to APU SKU so just force on all the features to driver
inquired interface at early initial stage.
Signed-off-by: NPrike Liang <Prike.Liang@amd.com>
Reviewed-by: NHuang Rui <ray.huang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Fixes build error of:
"use of undeclared identifier 'RENOIR_A0'"

To fix the same, this patch re-orders the
ASIC declarations accordingly.

Fixes: 41ef3dcd ("drm/amd/display: Fix RV2 Variant Detection")
Signed-off-by: NShirish S <shirish.s@amd.com>
Reviewed-by: NZhan Liu <zhan.liu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

1.Using the FCLK DPM table to set the MCLK for DPM states consist of
three entities:
 FCLK
 UCLK
 MEMCLK
All these three clk change together, MEMCLK from FCLK, so use the fclk
frequency.
2.we should show the current working clock freqency from clock table metric
Signed-off-by: NYuxian Dai <Yuxian.Dai@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NHuang Rui <ray.huang@amd.com>
Reviewed-by: NKevin Wang <Kevin1.Wang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Originally, it kfrees the wrong pointer for mem_obj.
It would cause memory leak under stress test.
Signed-off-by: NJack Zhang <Jack.Zhang1@amd.com>
Acked-by: NNirmoy Das <nirmoy.das@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
Some displays have an issue where the hdcp chips are initialized after the
display has already lit up. This means we can sometimes authentication too early
and cause authentication failures.

This happens when HDCP is enabled and the display is power cycled. Normally we
will authenticate 2 seconds after the display is lit, but some displays need a
bit more time.

[How]
Increase delay to 3 second before we start authentication.
Signed-off-by: NBhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: NNicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
-We need to cancel future callbacks/watchdogs events when a callback/watchdog event happens

[How]
-fix typo in event_callback()
	-cancel callback, not watchdog
-cancel watchdog events in event_watchdog_timer().
Signed-off-by: NBhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: NNicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
When content type property is set to 1. We should enable hdcp2.2 and if we cant
then stop. Currently the way it works in DC is that if we fail hdcp2, we will
try hdcp1 after.

[How]
Use link config to force disable hdcp1.4 when type1 is set.
Signed-off-by: NBhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: NNicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

This is ASIC specific and should be placed in _ppt.c of each ASIC.
Signed-off-by: NEvan Quan <evan.quan@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

This is already done in soc15.c. And this is really ASIC specific
and should not be placed here.
Signed-off-by: NEvan Quan <evan.quan@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
DML expects num_states to exclude the duplicate state.

[How]
Set num_states to correct value to prevent array off-by-one error.  Also
refactor max clock level code for diags.
Signed-off-by: NDmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Signed-off-by: NGeorge Shen <george.shen@amd.com>
Reviewed-by: NDmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
BT2020 is not supported in COLOR_ENCODING property of planes.  Only
BT601 and BT709 was available.

[How]
Allow BT2020 as legit value in setting COLOR_ENCODING property.
Signed-off-by: NStylon Wang <stylon.wang@amd.com>
Reviewed-by: NNicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
Nominal pixel clock and EDID information differ in precision so although
monitor reports maximum refresh is 2x minimum, LFC was not being
enabled.

[How]
Use minimum refresh rate as nominal/2 when EDID dictates that min
refresh = max refresh/2.

v2: squash in 64 bit divide fix
Signed-off-by: NAric Cyr <aric.cyr@amd.com>
Reviewed-by: NNicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
CTM was only supported at CRTC level and we need color space conversion
in linear space at plane level.

[How]
- Add plane-level CTM to dc interface
- Program plane-level CTM in DCN
Signed-off-by: NStylon Wang <stylon.wang@amd.com>
Reviewed-by: NNicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
Change is causing a regression where the OPC app no longer functions
properly.

[How]
Revert the changelist causing the issue.
Signed-off-by: NIsabel Zhang <isabel.zhang@amd.com>
Reviewed-by: NYongqiang Sun <yongqiang.sun@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
In some scenario like 1366x768 VSR enabled connected with a 4K monitor
and playing 4K video in clone mode, underflow will be observed due to
decrease dppclk when previouse surface scan isn't finished

[How]
In this use case, surface flip is switching between 4K and 1366x768,
1366x768 needs smaller dppclk, and when decrease the clk and previous
surface scan is for 4K and scan isn't done, underflow will happen.  Not
doing optimize bandwidth in case of flip pending.
Signed-off-by: NYongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: NTony Cheng <Tony.Cheng@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
For some monitors extreme flickering can occur while using LFC for if
we're not doing the DRR timing update for V_TOTAL_MIN / V_TOTAL_MAX at
the DP start of frame.

Hardware can default to any time in the frame which isn't the behavior
we want.

[How]
Add a new function for setting the double buffering mode for DRR timing.

Default to DP start of frame double buffering on timing generator init.
Signed-off-by: NNicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: NAric Cyr <Aric.Cyr@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
P010 pixel format is not declared as supported in DRM and DM.

[How]
Add P010 format to the support list presented to DRM and checked in DM
Signed-off-by: NStylon Wang <stylon.wang@amd.com>
Reviewed-by: NNicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

[Why]
Diagnostics scaling test failing to set required number of vertical taps
in 4:2:0 surface case

[How]
In dpp3_get_optimal_number_of_taps() need to use LB_MEMORY_CONFIG_3 for
4:2:0 surface case. In resource_build_scaling_params() make sure to also
set plane res alpha enable based on updated surface state
Signed-off-by: NEric Bernstein <eric.bernstein@amd.com>
Reviewed-by: NDmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

the HPD bo size calculation error.
the "mem.size" can't present actual BO size all time.
Signed-off-by: NKevin Wang <kevin1.wang@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NChristian König <Christian.Koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

A bit smaller this time around.. there are still a couple uabi
additions for vulkan waiting in the wings, but I punted on them this
cycle due to running low on time.  (They should be easy enough to
rebase, and if it is a problem for anyone I can push a next+uabi
branch so that tu work can proceed.)

The bigger change is refactoring dpu resource manager and moving dpu
to use atomic global state.  Other than that, it is mostly cleanups
and fixes.

From: Rob Clark <robdclark@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ <CAF6AEGuf1R4Xz-t9Z7_cwx9jD=b4wUvvwfqA5cHR8fCSXSd5XQ@mail.gmail.com
Signed-off-by: NDave Airlie <airlied@redhat.com>

msm needed rc6, so I just went and merged release
(msm has been in drm-next outside of this tree)
Signed-off-by: NDave Airlie <airlied@redhat.com>

Merge tag 'drm-intel-next-fixes-2020-03-27' of git://anongit.freedesktop.org/drm/drm-intel into drm-next

Fixes for instability on Baytrail and Haswell;
Ice Lake RPS; Sandy Bridge RC6; and few others around
GT hangchec/reset; livelock; and a null dereference.
Signed-off-by: NDave Airlie <airlied@redhat.com>

From: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200327081607.GA3082710@intel.com

amd-drm-next-5.7-2020-03-26:

amdgpu:
- Remove a dpm quirk that is not necessary
- Fix handling of AC/DC mode in newer SMU firmwares on navi
- SR-IOV fixes
- RAS fixes

scheduler:
- Fix a race condition

radeon:
- Remove a dpm quirk that is not necessary
Signed-off-by: NDave Airlie <airlied@redhat.com>
From: Alex Deucher <alexdeucher@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200326155310.5486-1-alexander.deucher@amd.com

Merge vm fixes from Andrew Morton:
 "5 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm/sparse: fix kernel crash with pfn_section_valid check
  mm: fork: fix kernel_stack memcg stats for various stack implementations
  hugetlb_cgroup: fix illegal access to memory
  drivers/base/memory.c: indicate all memory blocks as removable
  mm/swapfile.c: move inode_lock out of claim_swapfile

Pull timer fix from Thomas Gleixner:
 "A single fix for the Hyper-V clocksource driver to make sched clock
  actually return nanoseconds and not the virtual clock value which
  increments at 10e7 HZ (100ns)"

* tag 'timers-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource/drivers/hyper-v: Make sched clock return nanoseconds correctly

Pull irq fix from Thomas Gleixner:
 "A single bugfix to prevent reference leaks in irq affinity notifiers"

* tag 'irq-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Fix reference leaks on irq affinity notifiers

Fix the crash like this:

    BUG: Kernel NULL pointer dereference on read at 0x00000000
    Faulting instruction address: 0xc000000000c3447c
    Oops: Kernel access of bad area, sig: 11 [#1]
    LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
    CPU: 11 PID: 7519 Comm: lt-ndctl Not tainted 5.6.0-rc7-autotest #1
    ...
    NIP [c000000000c3447c] vmemmap_populated+0x98/0xc0
    LR [c000000000088354] vmemmap_free+0x144/0x320
    Call Trace:
       section_deactivate+0x220/0x240
       __remove_pages+0x118/0x170
       arch_remove_memory+0x3c/0x150
       memunmap_pages+0x1cc/0x2f0
       devm_action_release+0x30/0x50
       release_nodes+0x2f8/0x3e0
       device_release_driver_internal+0x168/0x270
       unbind_store+0x130/0x170
       drv_attr_store+0x44/0x60
       sysfs_kf_write+0x68/0x80
       kernfs_fop_write+0x100/0x290
       __vfs_write+0x3c/0x70
       vfs_write+0xcc/0x240
       ksys_write+0x7c/0x140
       system_call+0x5c/0x68

The crash is due to NULL dereference at

	test_bit(idx, ms->usage->subsection_map);

due to ms->usage = NULL in pfn_section_valid()

With commit d41e2f3b ("mm/hotplug: fix hot remove failure in
SPARSEMEM|!VMEMMAP case") section_mem_map is set to NULL after
depopulate_section_mem().  This was done so that pfn_page() can work
correctly with kernel config that disables SPARSEMEM_VMEMMAP.  With that
config pfn_to_page does

	__section_mem_map_addr(__sec) + __pfn;

where

  static inline struct page *__section_mem_map_addr(struct mem_section *section)
  {
	unsigned long map = section->section_mem_map;
	map &= SECTION_MAP_MASK;
	return (struct page *)map;
  }

Now with SPASEMEM_VMEMAP enabled, mem_section->usage->subsection_map is
used to check the pfn validity (pfn_valid()).  Since section_deactivate
release mem_section->usage if a section is fully deactivated,
pfn_valid() check after a subsection_deactivate cause a kernel crash.

  static inline int pfn_valid(unsigned long pfn)
  {
  ...
	return early_section(ms) || pfn_section_valid(ms, pfn);
  }

where

  static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
  {
	int idx = subsection_map_index(pfn);

	return test_bit(idx, ms->usage->subsection_map);
  }

Avoid this by clearing SECTION_HAS_MEM_MAP when mem_section->usage is
freed.  For architectures like ppc64 where large pages are used for
vmmemap mapping (16MB), a specific vmemmap mapping can cover multiple
sections.  Hence before a vmemmap mapping page can be freed, the kernel
needs to make sure there are no valid sections within that mapping.
Clearing the section valid bit before depopulate_section_memap enables
this.

[aneesh.kumar@linux.ibm.com: add comment]
  Link: http://lkml.kernel.org/r/20200326133235.343616-1-aneesh.kumar@linux.ibm.comLink: http://lkml.kernel.org/r/20200325031914.107660-1-aneesh.kumar@linux.ibm.com
Fixes: d41e2f3b ("mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case")
Reported-by: NSachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Tested-by: NSachin Sant <sachinp@linux.vnet.ibm.com>
Reviewed-by: NBaoquan He <bhe@redhat.com>
Reviewed-by: NWei Yang <richard.weiyang@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NPankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Depending on CONFIG_VMAP_STACK and the THREAD_SIZE / PAGE_SIZE ratio the
space for task stacks can be allocated using __vmalloc_node_range(),
alloc_pages_node() and kmem_cache_alloc_node().

In the first and the second cases page->mem_cgroup pointer is set, but
in the third it's not: memcg membership of a slab page should be
determined using the memcg_from_slab_page() function, which looks at
page->slab_cache->memcg_params.memcg .  In this case, using
mod_memcg_page_state() (as in account_kernel_stack()) is incorrect:
page->mem_cgroup pointer is NULL even for pages charged to a non-root
memory cgroup.

It can lead to kernel_stack per-memcg counters permanently showing 0 on
some architectures (depending on the configuration).

In order to fix it, let's introduce a mod_memcg_obj_state() helper,
which takes a pointer to a kernel object as a first argument, uses
mem_cgroup_from_obj() to get a RCU-protected memcg pointer and calls
mod_memcg_state().  It allows to handle all possible configurations
(CONFIG_VMAP_STACK and various THREAD_SIZE/PAGE_SIZE values) without
spilling any memcg/kmem specifics into fork.c .

Note: This is a special version of the patch created for stable
backports.  It contains code from the following two patches:
  - mm: memcg/slab: introduce mem_cgroup_from_obj()
  - mm: fork: fix kernel_stack memcg stats for various stack implementations

[guro@fb.com: introduce mem_cgroup_from_obj()]
  Link: http://lkml.kernel.org/r/20200324004221.GA36662@carbon.dhcp.thefacebook.com
Fixes: 4d96ba35 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
Signed-off-by: NRoman Gushchin <guro@fb.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200303233550.251375-1-guro@fb.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This appears to be a mistake in commit faced7e0 ("mm: hugetlb
controller for cgroups v2").

Essentially that commit does a hugetlb_cgroup_from_counter assuming that
page_counter_try_charge has initialized counter.

But if that has failed then it seems will not initialize counter, so
hugetlb_cgroup_from_counter(counter) ends up pointing to random memory,
causing kasan to complain.

The solution is to simply use 'h_cg', instead of
hugetlb_cgroup_from_counter(counter), since that is a reference to the
hugetlb_cgroup anyway.  After this change kasan ceases to complain.

Fixes: faced7e0 ("mm: hugetlb controller for cgroups v2")
Reported-by: syzbot+cac0c4e204952cf449b1@syzkaller.appspotmail.com
Signed-off-by: NMina Almasry <almasrymina@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NGiuseppe Scrivano <gscrivan@redhat.com>
Acked-by: NTejun Heo <tj@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/20200313223920.124230-1-almasrymina@google.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We see multiple issues with the implementation/interface to compute
whether a memory block can be offlined (exposed via
/sys/devices/system/memory/memoryX/removable) and would like to simplify
it (remove the implementation).

1. It runs basically lockless. While this might be good for performance,
   we see possible races with memory offlining that will require at
   least some sort of locking to fix.

2. Nowadays, more false positives are possible. No arch-specific checks
   are performed that validate if memory offlining will not be denied
   right away (and such check will require locking). For example, arm64
   won't allow to offline any memory block that was added during boot -
   which will imply a very high error rate. Other archs have other
   constraints.

3. The interface is inherently racy. E.g., if a memory block is detected
   to be removable (and was not a false positive at that time), there is
   still no guarantee that offlining will actually succeed. So any
   caller already has to deal with false positives.

4. It is unclear which performance benefit this interface actually
   provides. The introducing commit 5c755e9f ("memory-hotplug: add
   sysfs removable attribute for hotplug memory remove") mentioned

	"A user-level agent must be able to identify which sections
	 of memory are likely to be removable before attempting the
	 potentially expensive operation."

   However, no actual performance comparison was included.

Known users:

 - lsmem: Will group memory blocks based on the "removable" property. [1]

 - chmem: Indirect user. It has a RANGE mode where one can specify
          removable ranges identified via lsmem to be offlined. However,
          it also has a "SIZE" mode, which allows a sysadmin to skip the
          manual "identify removable blocks" step. [2]

 - powerpc-utils: Uses the "removable" attribute to skip some memory
          blocks right away when trying to find some to offline+remove.
          However, with ballooning enabled, it already skips this
          information completely (because it once resulted in many false
          negatives). Therefore, the implementation can deal with false
          positives properly already. [3]

According to Nathan Fontenot, DLPAR on powerpc is nowadays no longer
driven from userspace via the drmgr command (powerpc-utils).  Nowadays
it's managed in the kernel - including onlining/offlining of memory
blocks - triggered by drmgr writing to /sys/kernel/dlpar.  So the
affected legacy userspace handling is only active on old kernels.  Only
very old versions of drmgr on a new kernel (unlikely) might execute
slower - totally acceptable.

With CONFIG_MEMORY_HOTREMOVE, always indicating "removable" should not
break any user space tool.  We implement a very bad heuristic now.
Without CONFIG_MEMORY_HOTREMOVE we cannot offline anything, so report
"not removable" as before.

Original discussion can be found in [4] ("[PATCH RFC v1] mm:
is_mem_section_removable() overhaul").

Other users of is_mem_section_removable() will be removed next, so that
we can remove is_mem_section_removable() completely.

[1] http://man7.org/linux/man-pages/man1/lsmem.1.html
[2] http://man7.org/linux/man-pages/man8/chmem.8.html
[3] https://github.com/ibm-power-utilities/powerpc-utils
[4] https://lkml.kernel.org/r/20200117105759.27905-1-david@redhat.com

Also, this patch probably fixes a crash reported by Steve.
http://lkml.kernel.org/r/CAPcyv4jpdaNvJ67SkjyUJLBnBnXXQv686BiVW042g03FUmWLXw@mail.gmail.comReported-by: N"Scargall, Steve" <steve.scargall@intel.com>
Suggested-by: NMichal Hocko <mhocko@kernel.org>
Signed-off-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NNathan Fontenot <ndfont@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Karel Zak <kzak@redhat.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200128093542.6908-1-david@redhat.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

claim_swapfile() currently keeps the inode locked when it is successful,
or the file is already swapfile (with -EBUSY).  And, on the other error
cases, it does not lock the inode.

This inconsistency of the lock state and return value is quite confusing
and actually causing a bad unlock balance as below in the "bad_swap"
section of __do_sys_swapon().

This commit fixes this issue by moving the inode_lock() and IS_SWAPFILE
check out of claim_swapfile().  The inode is unlocked in
"bad_swap_unlock_inode" section, so that the inode is ensured to be
unlocked at "bad_swap".  Thus, error handling codes after the locking now
jumps to "bad_swap_unlock_inode" instead of "bad_swap".

    =====================================
    WARNING: bad unlock balance detected!
    5.5.0-rc7+ #176 Not tainted
    -------------------------------------
    swapon/4294 is trying to release lock (&sb->s_type->i_mutex_key) at: __do_sys_swapon+0x94b/0x3550
    but there are no more locks to release!

    other info that might help us debug this:
    no locks held by swapon/4294.

    stack backtrace:
    CPU: 5 PID: 4294 Comm: swapon Not tainted 5.5.0-rc7-BTRFS-ZNS+ #176
    Hardware name: ASUS All Series/H87-PRO, BIOS 2102 07/29/2014
    Call Trace:
     dump_stack+0xa1/0xea
     print_unlock_imbalance_bug.cold+0x114/0x123
     lock_release+0x562/0xed0
     up_write+0x2d/0x490
     __do_sys_swapon+0x94b/0x3550
     __x64_sys_swapon+0x54/0x80
     do_syscall_64+0xa4/0x4b0
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x7f15da0a0dc7

Fixes: 1638045c ("mm: set S_SWAPFILE on blockdev swap devices")
Signed-off-by: NNaohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Tested-by: NQais Youef <qais.yousef@arm.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200206090132.154869-1-naohiro.aota@wdc.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>