linux-stable.git/drivers/gpu/drm/v3d, branch linux-6.10.y

drm/v3d: Prevent out of bounds access in performance query extensions

2024-10-10T10:00:49+00:00

commit f32b5128d2c440368b5bf3a7a356823e235caabb upstream.

Check that the number of perfmons userspace is passing in the copy and
reset extensions is not greater than the internal kernel storage where
the ids will be copied into.

Signed-off-by: Tvrtko Ursulin 
Fixes: bae7cb5d6800 ("drm/v3d: Create a CPU job extension for the reset performance query job")
Cc: Maíra Canal 
Cc: Iago Toral Quiroga 
Cc: stable@vger.kernel.org # v6.8+
Reviewed-by: Iago Toral Quiroga 
Reviewed-by: Maíra Canal 
Signed-off-by: Maíra Canal 
Link: https://patchwork.freedesktop.org/patch/msgid/20240711135340.84617-2-tursulin@igalia.com
Signed-off-by: Greg Kroah-Hartman

drm/v3d: Disable preemption while updating GPU stats

2024-09-04T11:30:00+00:00

commit 9d824c7fce58f59982228aa85b0376b113cdfa35 upstream.

We forgot to disable preemption around the write_seqcount_begin/end() pair
while updating GPU stats:

  [ ] WARNING: CPU: 2 PID: 12 at include/linux/seqlock.h:221 __seqprop_assert.isra.0+0x128/0x150 [v3d]
  [ ] Workqueue: v3d_bin drm_sched_run_job_work [gpu_sched]
 <...snip...>
  [ ] Call trace:
  [ ]  __seqprop_assert.isra.0+0x128/0x150 [v3d]
  [ ]  v3d_job_start_stats.isra.0+0x90/0x218 [v3d]
  [ ]  v3d_bin_job_run+0x23c/0x388 [v3d]
  [ ]  drm_sched_run_job_work+0x520/0x6d0 [gpu_sched]
  [ ]  process_one_work+0x62c/0xb48
  [ ]  worker_thread+0x468/0x5b0
  [ ]  kthread+0x1c4/0x1e0
  [ ]  ret_from_fork+0x10/0x20

Fix it.

Cc: Maíra Canal 
Cc: stable@vger.kernel.org # v6.10+
Fixes: 6abe93b621ab ("drm/v3d: Fix race-condition between sysfs/fdinfo and interrupt handler")
Signed-off-by: Tvrtko Ursulin 
Acked-by: Maíra Canal 
Signed-off-by: Maíra Canal 
Link: https://patchwork.freedesktop.org/patch/msgid/20240813102505.80512-1-tursulin@igalia.com
Signed-off-by: Greg Kroah-Hartman

drm/v3d: Fix out-of-bounds read in `v3d_csd_job_run()`

2024-08-29T15:35:51+00:00

[ Upstream commit 497d370a644d95a9f04271aa92cb96d32e84c770 ]

When enabling UBSAN on Raspberry Pi 5, we get the following warning:

[  387.894977] UBSAN: array-index-out-of-bounds in drivers/gpu/drm/v3d/v3d_sched.c:320:3
[  387.903868] index 7 is out of range for type '__u32 [7]'
[  387.909692] CPU: 0 PID: 1207 Comm: kworker/u16:2 Tainted: G        WC         6.10.3-v8-16k-numa #151
[  387.919166] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT)
[  387.925961] Workqueue: v3d_csd drm_sched_run_job_work [gpu_sched]
[  387.932525] Call trace:
[  387.935296]  dump_backtrace+0x170/0x1b8
[  387.939403]  show_stack+0x20/0x38
[  387.942907]  dump_stack_lvl+0x90/0xd0
[  387.946785]  dump_stack+0x18/0x28
[  387.950301]  __ubsan_handle_out_of_bounds+0x98/0xd0
[  387.955383]  v3d_csd_job_run+0x3a8/0x438 [v3d]
[  387.960707]  drm_sched_run_job_work+0x520/0x6d0 [gpu_sched]
[  387.966862]  process_one_work+0x62c/0xb48
[  387.971296]  worker_thread+0x468/0x5b0
[  387.975317]  kthread+0x1c4/0x1e0
[  387.978818]  ret_from_fork+0x10/0x20
[  387.983014] ---[ end trace ]---

This happens because the UAPI provides only seven configuration
registers and we are reading the eighth position of this u32 array.

Therefore, fix the out-of-bounds read in `v3d_csd_job_run()` by
accessing only seven positions on the '__u32 [7]' array. The eighth
register exists indeed on V3D 7.1, but it isn't currently used. That
being so, let's guarantee that it remains unused and add a note that it
could be set in a future patch.

Fixes: 0ad5bc1ce463 ("drm/v3d: fix up register addresses for V3D 7.x")
Reported-by: Tvrtko Ursulin 
Signed-off-by: Maíra Canal 
Reviewed-by: Iago Toral Quiroga 
Link: https://patchwork.freedesktop.org/patch/msgid/20240809152001.668314-1-mcanal@igalia.com
Signed-off-by: Sasha Levin

drm/v3d: Validate passed in drm syncobj handles in the performance extension

2024-08-11T10:58:01+00:00

commit 4ecc24a84d7e0254efd150ec23e0b89638386516 upstream.

If userspace provides an unknown or invalid handle anywhere in the handle
array the rest of the driver will not handle that well.

Fix it by checking handle was looked up successfully or otherwise fail the
extension by jumping into the existing unwind.

Signed-off-by: Tvrtko Ursulin 
Fixes: bae7cb5d6800 ("drm/v3d: Create a CPU job extension for the reset performance query job")
Cc: Maíra Canal 
Cc: Iago Toral Quiroga 
Cc: stable@vger.kernel.org # v6.8+
Reviewed-by: Maíra Canal 
Signed-off-by: Maíra Canal 
Link: https://patchwork.freedesktop.org/patch/msgid/20240711135340.84617-6-tursulin@igalia.com
(cherry picked from commit a546b7e4d73c23838d7e4d2c92882b3ca902d213)
Signed-off-by: Thomas Zimmermann 
Signed-off-by: Greg Kroah-Hartman

drm/v3d: Validate passed in drm syncobj handles in the timestamp extension

2024-08-11T10:58:00+00:00

commit 023d22e8bb0cdd6900382ad1ed06df3b6c2ea791 upstream.

If userspace provides an unknown or invalid handle anywhere in the handle
array the rest of the driver will not handle that well.

Fix it by checking handle was looked up successfully or otherwise fail the
extension by jumping into the existing unwind.

Signed-off-by: Tvrtko Ursulin 
Fixes: 9ba0ff3e083f ("drm/v3d: Create a CPU job extension for the timestamp query job")
Cc: Maíra Canal 
Cc: Iago Toral Quiroga 
Cc: stable@vger.kernel.org # v6.8+
Reviewed-by: Maíra Canal 
Signed-off-by: Maíra Canal 
Link: https://patchwork.freedesktop.org/patch/msgid/20240711135340.84617-5-tursulin@igalia.com
(cherry picked from commit 8d1276d1b8f738c3afe1457d4dff5cc66fc848a3)
Signed-off-by: Thomas Zimmermann 
Signed-off-by: Greg Kroah-Hartman

drm/v3d: Fix potential memory leak in the performance extension

2024-08-11T10:58:00+00:00

commit 32df4abc44f24dbec239d43e2b26d5768c5d1a78 upstream.

If fetching of userspace memory fails during the main loop, all drm sync
objs looked up until that point will be leaked because of the missing
drm_syncobj_put.

Fix it by exporting and using a common cleanup helper.

Signed-off-by: Tvrtko Ursulin 
Fixes: bae7cb5d6800 ("drm/v3d: Create a CPU job extension for the reset performance query job")
Cc: Maíra Canal 
Cc: Iago Toral Quiroga 
Cc: stable@vger.kernel.org # v6.8+
Signed-off-by: Maíra Canal 
Link: https://patchwork.freedesktop.org/patch/msgid/20240711135340.84617-4-tursulin@igalia.com
(cherry picked from commit 484de39fa5f5b7bd0c5f2e2c5265167250ef7501)
Signed-off-by: Thomas Zimmermann 
Signed-off-by: Greg Kroah-Hartman

drm/v3d: Fix potential memory leak in the timestamp extension

2024-08-11T10:58:00+00:00

commit 0e50fcc20bd87584840266e8004f9064a8985b4f upstream.

If fetching of userspace memory fails during the main loop, all drm sync
objs looked up until that point will be leaked because of the missing
drm_syncobj_put.

Fix it by exporting and using a common cleanup helper.

Signed-off-by: Tvrtko Ursulin 
Fixes: 9ba0ff3e083f ("drm/v3d: Create a CPU job extension for the timestamp query job")
Cc: Maíra Canal 
Cc: Iago Toral Quiroga 
Cc: stable@vger.kernel.org # v6.8+
Reviewed-by: Maíra Canal 
Signed-off-by: Maíra Canal 
Link: https://patchwork.freedesktop.org/patch/msgid/20240711135340.84617-3-tursulin@igalia.com
(cherry picked from commit 753ce4fea62182c77e1691ab4f9022008f25b62e)
Signed-off-by: Thomas Zimmermann 
Signed-off-by: Greg Kroah-Hartman

drm/v3d: Prevent out of bounds access in performance query extensions

2024-08-11T10:58:00+00:00

commit 6ce9efd12ae81cf46bf44eb0348594558dfbb9d2 upstream.

Check that the number of perfmons userspace is passing in the copy and
reset extensions is not greater than the internal kernel storage where
the ids will be copied into.

Signed-off-by: Tvrtko Ursulin 
Fixes: bae7cb5d6800 ("drm/v3d: Create a CPU job extension for the reset performance query job")
Cc: Maíra Canal 
Cc: Iago Toral Quiroga 
Cc: stable@vger.kernel.org # v6.8+
Reviewed-by: Iago Toral Quiroga 
Reviewed-by: Maíra Canal 
Signed-off-by: Maíra Canal 
Link: https://patchwork.freedesktop.org/patch/msgid/20240711135340.84617-2-tursulin@igalia.com
(cherry picked from commit f32b5128d2c440368b5bf3a7a356823e235caabb)
Signed-off-by: Thomas Zimmermann 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-05-19T16:21:03+00:00

Pull mm updates from Andrew Morton:
"The usual shower of singleton fixes and minor series all over MM,
documented (hopefully adequately) in the respective changelogs.
Notable series include:

- Lucas Stach has provided some page-mapping cleanup/consolidation/
maintainability work in the series "mm/treewide: Remove pXd_huge()
API".

- In the series "Allow migrate on protnone reference with
MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's
MPOL_PREFERRED_MANY mode, yielding almost doubled performance in
one test.

- In their series "Memory allocation profiling" Kent Overstreet and
Suren Baghdasaryan have contributed a means of determining (via
/proc/allocinfo) whereabouts in the kernel memory is being
allocated: number of calls and amount of memory.

- Matthew Wilcox has provided the series "Various significant MM
patches" which does a number of rather unrelated things, but in
largely similar code sites.

- In his series "mm: page_alloc: freelist migratetype hygiene"
Johannes Weiner has fixed the page allocator's handling of
migratetype requests, with resulting improvements in compaction
efficiency.

- In the series "make the hugetlb migration strategy consistent"
Baolin Wang has fixed a hugetlb migration issue, which should
improve hugetlb allocation reliability.

- Liu Shixin has hit an I/O meltdown caused by readahead in a
memory-tight memcg. Addressed in the series "Fix I/O high when
memory almost met memcg limit".

- In the series "mm/filemap: optimize folio adding and splitting"
Kairui Song has optimized pagecache insertion, yielding ~10%
performance improvement in one test.

- Baoquan He has cleaned up and consolidated the early zone
initialization code in the series "mm/mm_init.c: refactor
free_area_init_core()".

- Baoquan has also redone some MM initializatio code in the series
"mm/init: minor clean up and improvement".

- MM helper cleanups from Christoph Hellwig in his series "remove
follow_pfn".

- More cleanups from Matthew Wilcox in the series "Various
page->flags cleanups".

- Vlastimil Babka has contributed maintainability improvements in the
series "memcg_kmem hooks refactoring".

- More folio conversions and cleanups in Matthew Wilcox's series:
"Convert huge_zero_page to huge_zero_folio"
"khugepaged folio conversions"
"Remove page_idle and page_young wrappers"
"Use folio APIs in procfs"
"Clean up __folio_put()"
"Some cleanups for memory-failure"
"Remove page_mapping()"
"More folio compat code removal"

- David Hildenbrand chipped in with "fs/proc/task_mmu: convert
hugetlb functions to work on folis".

- Code consolidation and cleanup work related to GUP's handling of
hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2".

- Rick Edgecombe has developed some fixes to stack guard gaps in the
series "Cover a guard gap corner case".

- Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the
series "mm/ksm: fix ksm exec support for prctl".

- Baolin Wang has implemented NUMA balancing for multi-size THPs.
This is a simple first-cut implementation for now. The series is
"support multi-size THP numa balancing".

- Cleanups to vma handling helper functions from Matthew Wilcox in
the series "Unify vma_address and vma_pgoff_address".

- Some selftests maintenance work from Dev Jain in the series
"selftests/mm: mremap_test: Optimizations and style fixes".

- Improvements to the swapping of multi-size THPs from Ryan Roberts
in the series "Swap-out mTHP without splitting".

- Kefeng Wang has significantly optimized the handling of arm64's
permission page faults in the series
"arch/mm/fault: accelerate pagefault when badaccess"
"mm: remove arch's private VM_FAULT_BADMAP/BADACCESS"

- GUP cleanups from David Hildenbrand in "mm/gup: consistently call
it GUP-fast".

- hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault
path to use struct vm_fault".

- selftests build fixes from John Hubbard in the series "Fix
selftests/mm build without requiring "make headers"".

- Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the
series "Improved Memory Tier Creation for CPUless NUMA Nodes".
Fixes the initialization code so that migration between different
memory types works as intended.

- David Hildenbrand has improved follow_pte() and fixed an errant
driver in the series "mm: follow_pte() improvements and acrn
follow_pte() fixes".

- David also did some cleanup work on large folio mapcounts in his
series "mm: mapcount for large folios + page_mapcount() cleanups".

- Folio conversions in KSM in Alex Shi's series "transfer page to
folio in KSM".

- Barry Song has added some sysfs stats for monitoring multi-size
THP's in the series "mm: add per-order mTHP alloc and swpout
counters".

- Some zswap cleanups from Yosry Ahmed in the series "zswap
same-filled and limit checking cleanups".

- Matthew Wilcox has been looking at buffer_head code and found the
documentation to be lacking. The series is "Improve buffer head
documentation".

- Multi-size THPs get more work, this time from Lance Yang. His
series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free"
optimizes the freeing of these things.

- Kemeng Shi has added more userspace-visible writeback
instrumentation in the series "Improve visibility of writeback".

- Kemeng Shi then sent some maintenance work on top in the series
"Fix and cleanups to page-writeback".

- Matthew Wilcox reduces mmap_lock traffic in the anon vma code in
the series "Improve anon_vma scalability for anon VMAs". Intel's
test bot reported an improbable 3x improvement in one test.

- SeongJae Park adds some DAMON feature work in the series
"mm/damon: add a DAMOS filter type for page granularity access recheck"
"selftests/damon: add DAMOS quota goal test"

- Also some maintenance work in the series
"mm/damon/paddr: simplify page level access re-check for pageout"
"mm/damon: misc fixes and improvements"

- David Hildenbrand has disabled some known-to-fail selftests ni the
series "selftests: mm: cow: flag vmsplice() hugetlb tests as
XFAIL".

- memcg metadata storage optimizations from Shakeel Butt in "memcg:
reduce memory consumption by memcg stats".

- DAX fixes and maintenance work from Vishal Verma in the series
"dax/bus.c: Fixups for dax-bus locking""

* tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits)
memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order
selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime
mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp
mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault
selftests: cgroup: add tests to verify the zswap writeback path
mm: memcg: make alloc_mem_cgroup_per_node_info() return bool
mm/damon/core: fix return value from damos_wmark_metric_value
mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED
selftests: cgroup: remove redundant enabling of memory controller
Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree
Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT
Docs/mm/damon/design: use a list for supported filters
Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command
Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file
selftests/damon: classify tests for functionalities and regressions
selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None'
selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts
selftests/damon/_damon_sysfs: check errors from nr_schemes file reads
mm/damon/core: initialize ->esz_bp from damos_quota_init_priv()
selftests/damon: add a test for DAMOS quota goal
...

fix missing vmalloc.h includes

2024-04-26T03:55:49+00:00

Patch series "Memory allocation profiling", v6.

Overview:
Low overhead [1] per-callsite memory allocation profiling. Not just for
debug kernels, overhead low enough to be deployed in production.

Example output:
  root@moria-kvm:~# sort -rn /proc/allocinfo
   127664128    31168 mm/page_ext.c:270 func:alloc_page_ext
    56373248     4737 mm/slub.c:2259 func:alloc_slab_page
    14880768     3633 mm/readahead.c:247 func:page_cache_ra_unbounded
    14417920     3520 mm/mm_init.c:2530 func:alloc_large_system_hash
    13377536      234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
    11718656     2861 mm/filemap.c:1919 func:__filemap_get_folio
     9192960     2800 kernel/fork.c:307 func:alloc_thread_stack_node
     4206592        4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
     4136960     1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
     3940352      962 mm/memory.c:4214 func:alloc_anon_folio
     2894464    22613 fs/kernfs/dir.c:615 func:__kernfs_new_node
     ...

Usage:
kconfig options:
 - CONFIG_MEM_ALLOC_PROFILING
 - CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
 - CONFIG_MEM_ALLOC_PROFILING_DEBUG
   adds warnings for allocations that weren't accounted because of a
   missing annotation

sysctl:
  /proc/sys/vm/mem_profiling

Runtime info:
  /proc/allocinfo

Notes:

[1]: Overhead
To measure the overhead we are comparing the following configurations:
(1) Baseline with CONFIG_MEMCG_KMEM=n
(2) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)
(3) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y)
(4) Enabled at runtime (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n && /proc/sys/vm/mem_profiling=1)
(5) Baseline with CONFIG_MEMCG_KMEM=y && allocating with __GFP_ACCOUNT
(6) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)  && CONFIG_MEMCG_KMEM=y
(7) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y) && CONFIG_MEMCG_KMEM=y

Performance overhead:
To evaluate performance we implemented an in-kernel test executing
multiple get_free_page/free_page and kmalloc/kfree calls with allocation
sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU
affinity set to a specific CPU to minimize the noise. Below are results
from running the test on Ubuntu 22.04.2 LTS with 6.8.0-rc1 kernel on
56 core Intel Xeon:

                        kmalloc                 pgalloc
(1 baseline)            6.764s                  16.902s
(2 default disabled)    6.793s  (+0.43%)        17.007s (+0.62%)
(3 default enabled)     7.197s  (+6.40%)        23.666s (+40.02%)
(4 runtime enabled)     7.405s  (+9.48%)        23.901s (+41.41%)
(5 memcg)               13.388s (+97.94%)       48.460s (+186.71%)
(6 def disabled+memcg)  13.332s (+97.10%)       48.105s (+184.61%)
(7 def enabled+memcg)   13.446s (+98.78%)       54.963s (+225.18%)

Memory overhead:
Kernel size:

   text           data        bss         dec         diff
(1) 26515311	      18890222    17018880    62424413
(2) 26524728	      19423818    16740352    62688898    264485
(3) 26524724	      19423818    16740352    62688894    264481
(4) 26524728	      19423818    16740352    62688898    264485
(5) 26541782	      18964374    16957440    62463596    39183

Memory consumption on a 56 core Intel CPU with 125GB of memory:
Code tags:           192 kB
PageExts:         262144 kB (256MB)
SlabExts:           9876 kB (9.6MB)
PcpuExts:            512 kB (0.5MB)

Total overhead is 0.2% of total memory.

Benchmarks:

Hackbench tests run 100 times:
hackbench -s 512 -l 200 -g 15 -f 25 -P
      baseline       disabled profiling           enabled profiling
avg   0.3543         0.3559 (+0.0016)             0.3566 (+0.0023)
stdev 0.0137         0.0188                       0.0077


hackbench -l 10000
      baseline       disabled profiling           enabled profiling
avg   6.4218         6.4306 (+0.0088)             6.5077 (+0.0859)
stdev 0.0933         0.0286                       0.0489

stress-ng tests:
stress-ng --class memory --seq 4 -t 60
stress-ng --class cpu --seq 4 -t 60
Results posted at: https://evilpiepirate.org/~kent/memalloc_prof_v4_stress-ng/

[2] https://lore.kernel.org/all/20240306182440.2003814-1-surenb@google.com/


This patch (of 37):

The next patch drops vmalloc.h from a system header in order to fix a
circular dependency; this adds it to all the files that were pulling it in
implicitly.

[kent.overstreet@linux.dev: fix arch/alpha/lib/memcpy.c]
  Link: https://lkml.kernel.org/r/20240327002152.3339937-1-kent.overstreet@linux.dev
[surenb@google.com: fix arch/x86/mm/numa_32.c]
  Link: https://lkml.kernel.org/r/20240402180933.1663992-1-surenb@google.com
[kent.overstreet@linux.dev: a few places were depending on sizes.h]
  Link: https://lkml.kernel.org/r/20240404034744.1664840-1-kent.overstreet@linux.dev
[arnd@arndb.de: fix mm/kasan/hw_tags.c]
  Link: https://lkml.kernel.org/r/20240404124435.3121534-1-arnd@kernel.org
[surenb@google.com: fix arc build]
  Link: https://lkml.kernel.org/r/20240405225115.431056-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-2-surenb@google.com
Signed-off-by: Kent Overstreet 
Signed-off-by: Suren Baghdasaryan 
Signed-off-by: Arnd Bergmann 
Reviewed-by: Pasha Tatashin 
Tested-by: Kees Cook 
Cc: Alexander Viro 
Cc: Alex Gaynor 
Cc: Alice Ryhl 
Cc: Andreas Hindborg 
Cc: Benno Lossin 
Cc: "Björn Roy Baron" 
Cc: Boqun Feng 
Cc: Christoph Lameter 
Cc: Dennis Zhou 
Cc: Gary Guo 
Cc: Miguel Ojeda 
Cc: Peter Zijlstra 
Cc: Tejun Heo 
Cc: Vlastimil Babka 
Cc: Wedson Almeida Filho 
Signed-off-by: Andrew Morton