* pm-cpufreq:
  cpufreq: intel_pstate: hybrid: Rework HWP calibration
  ACPI: CPPC: Introduce cppc_get_nominal_perf()

* pm-sleep:
  PM: sleep: core: Avoid setting power.must_resume to false
  PM: sleep: wakeirq: drop useless parameter from dev_pm_attach_wake_irq()

* pm-em:
  Documentation: power: include kernel-doc in Energy Model doc
  PM: EM: fix kernel-doc comments

I have been slow to respond to messages going to rjw@rjwysocki.net
recently, so change it to rafael@kernel.org (which works better for
me) in MAINTAINERS.

Signed-off-by: Rafael J. Wysocki <rafael@kernel.org>

Pull more power management updates from Rafael Wysocki:
 "These are mostly ARM cpufreq driver updates, including one new
  MediaTek driver that has just passed all of the reviews, with the
  addition of a revert of a recent intel_pstate commit, some core
  cpufreq changes and a DT-related update of the operating performance
  points (OPP) support code.

  Specifics:

   - Add new cpufreq driver for the MediaTek MT6779 platform called
     mediatek-hw along with corresponding DT bindings (Hector.Yuan).

   - Add DCVS interrupt support to the qcom-cpufreq-hw driver (Thara
     Gopinath).

   - Make the qcom-cpufreq-hw driver set the dvfs_possible_from_any_cpu
     policy flag (Taniya Das).

   - Blocklist more Qualcomm platforms in cpufreq-dt-platdev (Bjorn
     Andersson).

   - Make the vexpress cpufreq driver set the CPUFREQ_IS_COOLING_DEV
     flag (Viresh Kumar).

   - Add new cpufreq driver callback to allow drivers to register with
     the Energy Model in a consistent way and make several drivers use
     it (Viresh Kumar).

   - Change the remaining users of the .ready() cpufreq driver callback
     to move the code from it elsewhere and drop it from the cpufreq
     core (Viresh Kumar).

   - Revert recent intel_pstate change adding HWP guaranteed performance
     change notification support to it that led to problems, because the
     notification in question is triggered prematurely on some systems
     (Rafael Wysocki).

   - Convert the OPP DT bindings to DT schema and clean them up while at
     it (Rob Herring)"

* tag 'pm-5.15-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (23 commits)
  Revert "cpufreq: intel_pstate: Process HWP Guaranteed change notification"
  cpufreq: mediatek-hw: Add support for CPUFREQ HW
  cpufreq: Add of_perf_domain_get_sharing_cpumask
  dt-bindings: cpufreq: add bindings for MediaTek cpufreq HW
  cpufreq: Remove ready() callback
  cpufreq: sh: Remove sh_cpufreq_cpu_ready()
  cpufreq: acpi: Remove acpi_cpufreq_cpu_ready()
  cpufreq: qcom-hw: Set dvfs_possible_from_any_cpu cpufreq driver flag
  cpufreq: blocklist more Qualcomm platforms in cpufreq-dt-platdev
  cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support
  cpufreq: scmi: Use .register_em() to register with energy model
  cpufreq: vexpress: Use .register_em() to register with energy model
  cpufreq: scpi: Use .register_em() to register with energy model
  dt-bindings: opp: Convert to DT schema
  dt-bindings: Clean-up OPP binding node names in examples
  ARM: dts: omap: Drop references to opp.txt
  cpufreq: qcom-cpufreq-hw: Use .register_em() to register with energy model
  cpufreq: omap: Use .register_em() to register with energy model
  cpufreq: mediatek: Use .register_em() to register with energy model
  cpufreq: imx6q: Use .register_em() to register with energy model
  ...

Pull more ACPI updates from Rafael Wysocki:
 "These add ACPI support to the PCI VMD driver, improve suspend-to-idle
  support for AMD platforms and update documentation.

  Specifics:

   - Add ACPI support to the PCI VMD driver (Rafael Wysocki)

   - Rearrange suspend-to-idle support code to reflect the platform
     firmware expectations on some AMD platforms (Mario Limonciello)

   - Make SSDT overlays documentation follow the code documented by it
     more closely (Andy Shevchenko)"

* tag 'acpi-5.15-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: PM: s2idle: Run both AMD and Microsoft methods if both are supported
  Documentation: ACPI: Align the SSDT overlays file with the code
  PCI: VMD: ACPI: Make ACPI companion lookup work for VMD bus

Pull more documentation updates from Jonathan Corbet:
 "Another collection of documentation patches, mostly fixes but also
  includes another set of traditional Chinese translations"

* tag 'docs-5.15-2' of git://git.lwn.net/linux:
  docs: pdfdocs: Fix typo in CJK-language specific font settings
  docs: kernel-hacking: Remove inappropriate text
  docs/zh_TW: add translations for zh_TW/filesystems
  docs/zh_TW: add translations for zh_TW/cpu-freq
  docs/zh_TW: add translations for zh_TW/arm64
  docs/zh_CN: Modify the translator tag and fix the wrong word
  Documentation/features/vm: correct huge-vmap APIs
  Documentation: block: blk-mq: Fix small typo in multi-queue docs
  Documentation: in_irq() cleanup
  Documentation: arm: marvell: Add 88F6825 model into list
  Documentation/process/maintainer-pgp-guide: Replace broken link to PGP path finder
  Documentation: locking: fix references
  Documentation: Update details of The Linux Kernel Module Programming Guide
  docs: x86: Remove obsolete information about x86_64 vmalloc() faulting
  Documentation/process/applying-patches: Activate linux-next man hyperlink

Pull module updates from Jessica Yu:
 "The only main change I have for this round of updates is the modules
  MAINTAINERS update.

  As I find myself with less time to devote to upstream these days, Luis
  has kindly agreed to help maintain the module loader, to eventually
  transition to being the primary maintainer. Since Luis is already very
  involved upstream with experience maintaining various areas of the
  kernel including the kmod usermode helper, I think he is a great fit
  for this area of the kernel.

  Summary:

   - Add Luis Chamberlain as modules maintainer

   - Fix for .ctors sections in module linker script"

* tag 'modules-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
  MAINTAINERS: Add Luis Chamberlain as modules maintainer
  module: combine constructors in module linker script

Pull microblaze update from Michal Simek:

 - Kbuild clean up

* tag 'microblaze-v5.15' of git://git.monstr.eu/linux-2.6-microblaze:
  microblaze: move core-y in arch/microblaze/Makefile to arch/microblaze/Kbuild

Pull nfsd fixes from Chuck Lever:

 - Restore performance on memory-starved servers

* tag 'nfsd-5.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  SUNRPC: improve error response to over-size gss credential
  SUNRPC: don't pause on incomplete allocation

Pull ceph updates from Ilya Dryomov:

 - a set of patches to address fsync stalls caused by depending on
   periodic rather than triggered MDS journal flushes in some cases
   (Xiubo Li)

 - a fix for mtime effectively not getting updated in case of competing
   writers (Jeff Layton)

 - a couple of fixes for inode reference leaks and various WARNs after
   "umount -f" (Xiubo Li)

 - a new ceph.auth_mds extended attribute (Jeff Layton)

 - a smattering of fixups and cleanups from Jeff, Xiubo and Colin.

* tag 'ceph-for-5.15-rc1' of git://github.com/ceph/ceph-client:
  ceph: fix dereference of null pointer cf
  ceph: drop the mdsc_get_session/put_session dout messages
  ceph: lockdep annotations for try_nonblocking_invalidate
  ceph: don't WARN if we're forcibly removing the session caps
  ceph: don't WARN if we're force umounting
  ceph: remove the capsnaps when removing caps
  ceph: request Fw caps before updating the mtime in ceph_write_iter
  ceph: reconnect to the export targets on new mdsmaps
  ceph: print more information when we can't find snaprealm
  ceph: add ceph_change_snap_realm() helper
  ceph: remove redundant initializations from mdsc and session
  ceph: cancel delayed work instead of flushing on mdsc teardown
  ceph: add a new vxattr to return auth mds for an inode
  ceph: remove some defunct forward declarations
  ceph: flush the mdlog before waiting on unsafe reqs
  ceph: flush mdlog before umounting
  ceph: make iterate_sessions a global symbol
  ceph: make ceph_create_session_msg a global symbol
  ceph: fix comment about short copies in ceph_write_end
  ceph: fix memory leak on decode error in ceph_handle_caps

Pull 9p updates from Dominique Martinet:
 "A couple of harmless fixes, increase max tcp msize (64KB -> 1MB), and
  increase default msize (8KB -> 128KB)

  The default increase has been discussed with Christian for the qemu
  side of things but makes sense for all supported transports"

* tag '9p-for-5.15-rc1' of git://github.com/martinetd/linux:
  net/9p: increase default msize to 128k
  net/9p: use macro to define default msize
  net/9p: increase tcp max msize to 1MB
  9p/xen: Fix end of loop tests for list_for_each_entry
  9p/trans_virtio: Remove sysfs file on probe failure

Merge more updates from Andrew Morton:
 "147 patches, based on 7d2a07b7.

  Subsystems affected by this patch series: mm (memory-hotplug, rmap,
  ioremap, highmem, cleanups, secretmem, kfence, damon, and vmscan),
  alpha, percpu, procfs, misc, core-kernel, MAINTAINERS, lib,
  checkpatch, epoll, init, nilfs2, coredump, fork, pids, criu, kconfig,
  selftests, ipc, and scripts"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (94 commits)
  scripts: check_extable: fix typo in user error message
  mm/workingset: correct kernel-doc notations
  ipc: replace costly bailout check in sysvipc_find_ipc()
  selftests/memfd: remove unused variable
  Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
  configs: remove the obsolete CONFIG_INPUT_POLLDEV
  prctl: allow to setup brk for et_dyn executables
  pid: cleanup the stale comment mentioning pidmap_init().
  kernel/fork.c: unexport get_{mm,task}_exe_file
  coredump: fix memleak in dump_vma_snapshot()
  fs/coredump.c: log if a core dump is aborted due to changed file permissions
  nilfs2: use refcount_dec_and_lock() to fix potential UAF
  nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
  nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
  nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
  nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
  nilfs2: fix NULL pointer in nilfs_##name##_attr_release
  nilfs2: fix memory leak in nilfs_sysfs_create_device_group
  trap: cleanup trap_init()
  init: move usermodehelper_enable() to populate_rootfs()
  ...

Pull SLUB updates from Vlastimil Babka:
 "SLUB: reduce irq disabled scope and make it RT compatible

  This series was initially inspired by Mel's pcplist local_lock
  rewrite, and also interest to better understand SLUB's locking and the
  new primitives and RT variants and implications. It makes SLUB
  compatible with PREEMPT_RT and generally more preemption-friendly,
  apparently without significant regressions, as the fast paths are not
  affected.

  The main changes to SLUB by this series:

   - irq disabling is now only done for minimum amount of time needed to
     protect the strict kmem_cache_cpu fields, and as part of spin lock,
     local lock and bit lock operations to make them irq-safe

   - SLUB is fully PREEMPT_RT compatible

  The series should now be sufficiently tested in both RT and !RT
  configs, mainly thanks to Mike.

  The RFC/v1 version also got basic performance screening by Mel that
  didn't show major regressions. Mike's testing with hackbench of v2 on
  !RT reported negligible differences [6]:

    virgin(ish) tip
    5.13.0.g60ab3ed-tip
              7,320.67 msec task-clock                #    7.792 CPUs utilized            ( +-  0.31% )
               221,215      context-switches          #    0.030 M/sec                    ( +-  3.97% )
                16,234      cpu-migrations            #    0.002 M/sec                    ( +-  4.07% )
                13,233      page-faults               #    0.002 M/sec                    ( +-  0.91% )
        27,592,205,252      cycles                    #    3.769 GHz                      ( +-  0.32% )
         8,309,495,040      instructions              #    0.30  insn per cycle           ( +-  0.37% )
         1,555,210,607      branches                  #  212.441 M/sec                    ( +-  0.42% )
             5,484,209      branch-misses             #    0.35% of all branches          ( +-  2.13% )

               0.93949 +- 0.00423 seconds time elapsed  ( +-  0.45% )
               0.94608 +- 0.00384 seconds time elapsed  ( +-  0.41% ) (repeat)
               0.94422 +- 0.00410 seconds time elapsed  ( +-  0.43% )

    5.13.0.g60ab3ed-tip +slub-local-lock-v2r3
              7,343.57 msec task-clock                #    7.776 CPUs utilized            ( +-  0.44% )
               223,044      context-switches          #    0.030 M/sec                    ( +-  3.02% )
                16,057      cpu-migrations            #    0.002 M/sec                    ( +-  4.03% )
                13,164      page-faults               #    0.002 M/sec                    ( +-  0.97% )
        27,684,906,017      cycles                    #    3.770 GHz                      ( +-  0.45% )
         8,323,273,871      instructions              #    0.30  insn per cycle           ( +-  0.28% )
         1,556,106,680      branches                  #  211.901 M/sec                    ( +-  0.31% )
             5,463,468      branch-misses             #    0.35% of all branches          ( +-  1.33% )

               0.94440 +- 0.00352 seconds time elapsed  ( +-  0.37% )
               0.94830 +- 0.00228 seconds time elapsed  ( +-  0.24% ) (repeat)
               0.93813 +- 0.00440 seconds time elapsed  ( +-  0.47% ) (repeat)

  RT configs showed some throughput regressions, but that's expected
  tradeoff for the preemption improvements through the RT mutex. It
  didn't prevent the v2 to be incorporated to the 5.13 RT tree [7],
  leading to testing exposure and bugfixes.

  Before the series, SLUB is lockless in both allocation and free fast
  paths, but elsewhere, it's disabling irqs for considerable periods of
  time - especially in allocation slowpath and the bulk allocation,
  where IRQs are re-enabled only when a new page from the page allocator
  is needed, and the context allows blocking. The irq disabled sections
  can then include deactivate_slab() which walks a full freelist and
  frees the slab back to page allocator or unfreeze_partials() going
  through a list of percpu partial slabs. The RT tree currently has some
  patches mitigating these, but we can do much better in mainline too.

  Patches 1-6 are straightforward improvements or cleanups that could
  exist outside of this series too, but are prerequsities.

  Patches 7-9 are also preparatory code changes without functional
  changes, but not so useful without the rest of the series.

  Patch 10 simplifies the fast paths on systems with preemption, based
  on (hopefully correct) observation that the current loops to verify
  tid are unnecessary.

  Patches 11-20 focus on reducing irq disabled scope in the allocation
  slowpath:

   - patch 11 moves disabling of irqs into ___slab_alloc() from its
     callers, which are the allocation slowpath, and bulk allocation.
     Instead these callers only disable preemption to stabilize the cpu.

   - The following patches then gradually reduce the scope of disabled
     irqs in ___slab_alloc() and the functions called from there. As of
     patch 14, the re-enabling of irqs based on gfp flags before calling
     the page allocator is removed from allocate_slab(). As of patch 17,
     it's possible to reach the page allocator (in case of existing
     slabs depleted) without disabling and re-enabling irqs a single
     time.

  Pathces 21-26 reduce the scope of disabled irqs in functions related
  to unfreezing percpu partial slab.

  Patch 27 is preparatory. Patch 28 is adopted from the RT tree and
  converts the flushing of percpu slabs on all cpus from using IPI to
  workqueue, so that the processing isn't happening with irqs disabled
  in the IPI handler. The flushing is not performance critical so it
  should be acceptable.

  Patch 29 also comes from RT tree and makes object_map_lock RT
  compatible.

  Patch 30 make slab_lock irq-safe on RT where we cannot rely on having
  irq disabled from the list_lock spin lock usage.

  Patch 31 changes kmem_cache_cpu->partial handling in put_cpu_partial()
  from cmpxchg loop to a short irq disabled section, which is used by
  all other code modifying the field. This addresses a theoretical race
  scenario pointed out by Jann, and makes the critical section safe wrt
  with RT local_lock semantics after the conversion in patch 35.

  Patch 32 changes preempt disable to migrate disable, so that the
  nested list_lock spinlock is safe to take on RT. Because
  migrate_disable() is a function call even on !RT, a small set of
  private wrappers is introduced to keep using the cheaper
  preempt_disable() on !PREEMPT_RT configurations. As of this patch,
  SLUB should be already compatible with RT's lock semantics.

  Finally, patch 33 changes irq disabled sections that protect
  kmem_cache_cpu fields in the slow paths, with a local lock. However on
  PREEMPT_RT it means the lockless fast paths can now preempt slow paths
  which don't expect that, so the local lock has to be taken also in the
  fast paths and they are no longer lockless. RT folks seem to not mind
  this tradeoff. The patch also updates the locking documentation in the
  file's comment"

Mike Galbraith and Mel Gorman verified that their earlier testing
observations still hold for the final series:

Link: https://lore.kernel.org/lkml/89ba4f783114520c167cc915ba949ad2c04d6790.camel@gmx.de/
Link: https://lore.kernel.org/lkml/20210907082010.GB3959@techsingularity.net/

* tag 'mm-slub-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux: (33 commits)
  mm, slub: convert kmem_cpu_slab protection to local_lock
  mm, slub: use migrate_disable() on PREEMPT_RT
  mm, slub: protect put_cpu_partial() with disabled irqs instead of cmpxchg
  mm, slub: make slab_lock() disable irqs with PREEMPT_RT
  mm: slub: make object_map_lock a raw_spinlock_t
  mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context
  mm, slab: split out the cpu offline variant of flush_slab()
  mm, slub: don't disable irqs in slub_cpu_dead()
  mm, slub: only disable irq with spin_lock in __unfreeze_partials()
  mm, slub: separate detaching of partial list in unfreeze_partials() from unfreezing
  mm, slub: detach whole partial list at once in unfreeze_partials()
  mm, slub: discard slabs in unfreeze_partials() without irqs disabled
  mm, slub: move irq control into unfreeze_partials()
  mm, slub: call deactivate_slab() without disabling irqs
  mm, slub: make locking in deactivate_slab() irq-safe
  mm, slub: move reset of c->page and freelist out of deactivate_slab()
  mm, slub: stop disabling irqs around get_partial()
  mm, slub: check new pages with restored irqs
  mm, slub: validate slab from partial list or page allocator before making it cpu slab
  mm, slub: restore irqs around calling new_slab()
  ...

Fix typo ("and" should be "an") in an error message.

Link: https://lkml.kernel.org/r/20210727002943.29774-1-rdunlap@infradead.org


Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Use the documented kernel-doc format to prevent kernel-doc warnings.

mm/workingset.c:256: warning: No description found for return value of 'workingset_eviction'
mm/workingset.c:285: warning: Function parameter or member 'folio' not described in 'workingset_refault'
mm/workingset.c:285: warning: Excess function parameter 'page' description in 'workingset_refault'

Link: https://lkml.kernel.org/r/20210808203153.10678-1-rdunlap@infradead.org


Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sysvipc_find_ipc() was left with a costly way to check if the offset
position fed to it is bigger than the total number of IPC IDs in use.  So
much so that the time it takes to iterate over /proc/sysvipc/* files grows
exponentially for a custom benchmark that creates "N" SYSV shm segments
and then times the read of /proc/sysvipc/shm (milliseconds):

    12 msecs to read   1024 segs from /proc/sysvipc/shm
    18 msecs to read   2048 segs from /proc/sysvipc/shm
    65 msecs to read   4096 segs from /proc/sysvipc/shm
   325 msecs to read   8192 segs from /proc/sysvipc/shm
  1303 msecs to read  16384 segs from /proc/sysvipc/shm
  5182 msecs to read  32768 segs from /proc/sysvipc/shm

The root problem lies with the loop that computes the total amount of ids
in use to check if the "pos" feeded to sysvipc_find_ipc() grew bigger than
"ids->in_use".  That is a quite inneficient way to get to the maximum
index in the id lookup table, specially when that value is already
provided by struct ipc_ids.max_idx.

This patch follows up on the optimization introduced via commit
15df03c8 ("sysvipc: make get_maxid O(1) again") and gets rid of the
aforementioned costly loop replacing it by a simpler checkpoint based on
ipc_get_maxidx() returned value, which allows for a smooth linear increase
in time complexity for the same custom benchmark:

     2 msecs to read   1024 segs from /proc/sysvipc/shm
     2 msecs to read   2048 segs from /proc/sysvipc/shm
     4 msecs to read   4096 segs from /proc/sysvipc/shm
     9 msecs to read   8192 segs from /proc/sysvipc/shm
    19 msecs to read  16384 segs from /proc/sysvipc/shm
    39 msecs to read  32768 segs from /proc/sysvipc/shm

Link: https://lkml.kernel.org/r/20210809203554.1562989-1-aquini@redhat.com


Signed-off-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Waiman Long <llong@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 54402986 ("selftests/memfd: add tests for F_SEAL_FUTURE_WRITE
seal") added an unused variable to mfd_assert_reopen_fd().

Delete the unused variable.

Link: https://lkml.kernel.org/r/20210702045509.1517643-1-gthelen@google.com
Fixes: 54402986

 ("selftests/memfd: add tests for F_SEAL_FUTURE_WRITE seal")
Signed-off-by: Greg Thelen <gthelen@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 05a4a952 ("kernel/watchdog: split up config options") adds a
new config HARDLOCKUP_DETECTOR, which selects the non-existing config
HARDLOCKUP_DETECTOR_ARCH.

Hence, ./scripts/checkkconfigsymbols.py warns:

HARDLOCKUP_DETECTOR_ARCH Referencing files: lib/Kconfig.debug

Simply drop selecting the non-existing HARDLOCKUP_DETECTOR_ARCH.

Link: https://lkml.kernel.org/r/20210806115618.22088-1-lukas.bulwahn@gmail.com
Fixes: 05a4a952

 ("kernel/watchdog: split up config options")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Babu Moger <babu.moger@oracle.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This CONFIG option was removed in commit 278b13ce ("Input: remove
input_polled_dev implementation") so there's no point to keep it in
defconfigs any longer.

Get rid of the leftover for all arches.

Link: https://lkml.kernel.org/r/20210726074741.1062-1-yuzenghui@huawei.com


Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Keno Fischer reported that when a binray loaded via ld-linux-x the
prctl(PR_SET_MM_MAP) doesn't allow to setup brk value because it lays
before mm:end_data.

For example a test program shows

 | # ~/t
 |
 | start_code      401000
 | end_code        401a15
 | start_stack     7ffce4577dd0
 | start_data	   403e10
 | end_data        40408c
 | start_brk	   b5b000
 | sbrk(0)         b5b000

and when executed via ld-linux

 | # /lib64/ld-linux-x86-64.so.2 ~/t
 |
 | start_code      7fc25b0a4000
 | end_code        7fc25b0c4524
 | start_stack     7fffcc6b2400
 | start_data	   7fc25b0ce4c0
 | end_data        7fc25b0cff98
 | start_brk	   55555710c000
 | sbrk(0)         55555710c000

This of course prevent criu from restoring such programs.  Looking into
how kernel operates with brk/start_brk inside brk() syscall I don't see
any problem if we allow to setup brk/start_brk without checking for
end_data.  Even if someone pass some weird address here on a purpose then
the worst possible result will be an unexpected unmapping of existing vma
(own vma, since prctl works with the callers memory) but test for
RLIMIT_DATA is still valid and a user won't be able to gain more memory in
case of expanding VMAs via new values shipped with prctl call.

Link: https://lkml.kernel.org/r/20210121221207.GB2174@grain
Fixes: bbdc6076

 ("binfmt_elf: move brk out of mmap when doing direct loader exec")
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reported-by: Keno Fischer <keno@juliacomputing.com>
Acked-by: Andrey Vagin <avagin@gmail.com>
Tested-by: Andrey Vagin <avagin@gmail.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

pidmap_init() has already been replaced with pid_idr_init() in the commit
95846ecf ("pid: replace pid bitmap implementation with IDR API").
Cleanup the stale comment which still mentions it.

Link: https://lkml.kernel.org/r/20210714120713.19825-1-itazur@amazon.com


Signed-off-by: Takahiro Itazuri <itazur@amazon.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Only used by core code and the tomoyo which can't be a module either.

Link: https://lkml.kernel.org/r/20210820095430.445242-1-hch@lst.de


Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

dump_vma_snapshot() allocs memory for *vma_meta, when dump_vma_snapshot()
returns -EFAULT, the memory will be leaked, so we free it correctly.

Link: https://lkml.kernel.org/r/20210810020441.62806-1-qiuxi1@huawei.com
Fixes: a07279c9

 ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Signed-off-by: QiuXi <qiuxi1@huawei.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jann Horn <jannh@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

For obvious security reasons, a core dump is aborted if the filesystem
cannot preserve ownership or permissions of the dump file.

This affects filesystems like e.g.  vfat, but also something like a 9pfs
share in a Qemu test setup, running as a regular user, depending on the
security model used.  In those cases, the result is an empty core file and
a confused user.

To hopefully save other people a lot of time figuring out the cause, this
patch adds a simple log message for those specific cases.

[akpm@linux-foundation.org: s/|%s/%s/ in printk text]

Link: https://lkml.kernel.org/r/20210701233151.102720-1-david.oberhollenzer@sigma-star.at


Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When the refcount is decreased to 0, the resource reclamation branch is
entered.  Before CPU0 reaches the race point (1), CPU1 may obtain the
spinlock and traverse the rbtree to find 'root', see
nilfs_lookup_root().

Although CPU1 will call refcount_inc() to increase the refcount, it is
obviously too late.  CPU0 will release 'root' directly, CPU1 then
accesses 'root' and triggers UAF.

Use refcount_dec_and_lock() to ensure that both the operations of
decrease refcount to 0 and link deletion are lock protected eliminates
this risk.

	     CPU0                      CPU1
	nilfs_put_root():
		    <-------- (1)
				spin_lock(&nilfs->ns_cptree_lock);
				rb_erase(&root->rb_node, &nilfs->ns_cptree);
				spin_unlock(&nilfs->ns_cptree_lock);

	kfree(root);
		    <-------- use-after-free

  refcount_t: underflow; use-after-free.
  WARNING: CPU: 2 PID: 9476 at lib/refcount.c:28 \
  refcount_warn_saturate+0x1cf/0x210 lib/refcount.c:28
  Modules linked in:
  CPU: 2 PID: 9476 Comm: syz-executor.0 Not tainted 5.10.45-rc1+ #3
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ...
  RIP: 0010:refcount_warn_saturate+0x1cf/0x210 lib/refcount.c:28
  ... ...
  Call Trace:
     __refcount_sub_and_test include/linux/refcount.h:283 [inline]
     __refcount_dec_and_test include/linux/refcount.h:315 [inline]
     refcount_dec_and_test include/linux/refcount.h:333 [inline]
     nilfs_put_root+0xc1/0xd0 fs/nilfs2/the_nilfs.c:795
     nilfs_segctor_destroy fs/nilfs2/segment.c:2749 [inline]
     nilfs_detach_log_writer+0x3fa/0x570 fs/nilfs2/segment.c:2812
     nilfs_put_super+0x2f/0xf0 fs/nilfs2/super.c:467
     generic_shutdown_super+0xcd/0x1f0 fs/super.c:464
     kill_block_super+0x4a/0x90 fs/super.c:1446
     deactivate_locked_super+0x6a/0xb0 fs/super.c:335
     deactivate_super+0x85/0x90 fs/super.c:366
     cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
     __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
     task_work_run+0x8e/0x110 kernel/task_work.c:151
     tracehook_notify_resume include/linux/tracehook.h:188 [inline]
     exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
     exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
     syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
     do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
     entry_SYSCALL_64_after_hwframe+0x44/0xa9

There is no reproduction program, and the above is only theoretical
analysis.

Link: https://lkml.kernel.org/r/1629859428-5906-1-git-send-email-konishi.ryusuke@gmail.com
Fixes: ba65ae47 ("nilfs2: add checkpoint tree to nilfs object")
Link: https://lkml.kernel.org/r/20210723012317.4146-1-thunder.leizhen@huawei.com


Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kobject_put() should be used to cleanup the memory associated with the
kobject instead of kobject_del().  See the section "Kobject removal" of
"Documentation/core-api/kobject.rst".

Link: https://lkml.kernel.org/r/20210629022556.3985106-7-sunnanyong@huawei.com
Link: https://lkml.kernel.org/r/1625651306-10829-7-git-send-email-konishi.ryusuke@gmail.com


Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If kobject_init_and_add returns with error, kobject_put() is needed here
to avoid memory leak, because kobject_init_and_add may return error
without freeing the memory associated with the kobject it allocated.

Link: https://lkml.kernel.org/r/20210629022556.3985106-6-sunnanyong@huawei.com
Link: https://lkml.kernel.org/r/1625651306-10829-6-git-send-email-konishi.ryusuke@gmail.com


Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The kobject_put() should be used to cleanup the memory associated with the
kobject instead of kobject_del.  See the section "Kobject removal" of
"Documentation/core-api/kobject.rst".

Link: https://lkml.kernel.org/r/20210629022556.3985106-5-sunnanyong@huawei.com
Link: https://lkml.kernel.org/r/1625651306-10829-5-git-send-email-konishi.ryusuke@gmail.com


Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If kobject_init_and_add return with error, kobject_put() is needed here to
avoid memory leak, because kobject_init_and_add may return error without
freeing the memory associated with the kobject it allocated.

Link: https://lkml.kernel.org/r/20210629022556.3985106-4-sunnanyong@huawei.com
Link: https://lkml.kernel.org/r/1625651306-10829-4-git-send-email-konishi.ryusuke@gmail.com


Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In nilfs_##name##_attr_release, kobj->parent should not be referenced
because it is a NULL pointer.  The release() method of kobject is always
called in kobject_put(kobj), in the implementation of kobject_put(), the
kobj->parent will be assigned as NULL before call the release() method.
So just use kobj to get the subgroups, which is more efficient and can fix
a NULL pointer reference problem.

Link: https://lkml.kernel.org/r/20210629022556.3985106-3-sunnanyong@huawei.com
Link: https://lkml.kernel.org/r/1625651306-10829-3-git-send-email-konishi.ryusuke@gmail.com


Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "nilfs2: fix incorrect usage of kobject".

This patchset from Nanyong Sun fixes memory leak issues and a NULL
pointer dereference issue caused by incorrect usage of kboject in nilfs2
sysfs implementation.

This patch (of 6):

Reported by syzkaller:

  BUG: memory leak
  unreferenced object 0xffff888100ca8988 (size 8):
  comm "syz-executor.1", pid 1930, jiffies 4294745569 (age 18.052s)
  hex dump (first 8 bytes):
  6c 6f 6f 70 31 00 ff ff loop1...
  backtrace:
    kstrdup+0x36/0x70 mm/util.c:60
    kstrdup_const+0x35/0x60 mm/util.c:83
    kvasprintf_const+0xf1/0x180 lib/kasprintf.c:48
    kobject_set_name_vargs+0x56/0x150 lib/kobject.c:289
    kobject_add_varg lib/kobject.c:384 [inline]
    kobject_init_and_add+0xc9/0x150 lib/kobject.c:473
    nilfs_sysfs_create_device_group+0x150/0x7d0 fs/nilfs2/sysfs.c:986
    init_nilfs+0xa21/0xea0 fs/nilfs2/the_nilfs.c:637
    nilfs_fill_super fs/nilfs2/super.c:1046 [inline]
    nilfs_mount+0x7b4/0xe80 fs/nilfs2/super.c:1316
    legacy_get_tree+0x105/0x210 fs/fs_context.c:592
    vfs_get_tree+0x8e/0x2d0 fs/super.c:1498
    do_new_mount fs/namespace.c:2905 [inline]
    path_mount+0xf9b/0x1990 fs/namespace.c:3235
    do_mount+0xea/0x100 fs/namespace.c:3248
    __do_sys_mount fs/namespace.c:3456 [inline]
    __se_sys_mount fs/namespace.c:3433 [inline]
    __x64_sys_mount+0x14b/0x1f0 fs/namespace.c:3433
    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80
    entry_SYSCALL_64_after_hwframe+0x44/0xae

If kobject_init_and_add return with error, then the cleanup of kobject
is needed because memory may be allocated in kobject_init_and_add
without freeing.

And the place of cleanup_dev_kobject should use kobject_put to free the
memory associated with the kobject.  As the section "Kobject removal" of
"Documentation/core-api/kobject.rst" says, kobject_del() just makes the
kobject "invisible", but it is not cleaned up.  And no more cleanup will
do after cleanup_dev_kobject, so kobject_put is needed here.

Link: https://lkml.kernel.org/r/1625651306-10829-1-git-send-email-konishi.ryusuke@gmail.com
Link: https://lkml.kernel.org/r/1625651306-10829-2-git-send-email-konishi.ryusuke@gmail.com


Reported-by: Hulk Robot <hulkci@huawei.com>
Link: https://lkml.kernel.org/r/20210629022556.3985106-2-sunnanyong@huawei.com


Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There are some empty trap_init() definitions in different ARCHs, Introduce
a new weak trap_init() function to clean them up.

Link: https://lkml.kernel.org/r/20210812123602.76356-1-wangkefeng.wang@huawei.com


Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>	[arm32]
Acked-by: Vineet Gupta						[arc]
Acked-by: Michael Ellerman <mpe@ellerman.id.au>			[powerpc]
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <palmerdabbelt@google.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Currently, usermodehelper is enabled right before PID1 starts going
through the initcalls. However, any call of a usermodehelper from a
pure_, core_, postcore_, arch_, subsys_ or fs_ initcall is futile, as
there is no filesystem contents yet.

Up until commit e7cb072e ("init/initramfs.c: do unpacking
asynchronously"), such calls, whether via some request_module(), a
legacy uevent "/sbin/hotplug" notification or something else, would
just fail silently with (presumably) -ENOENT from
kernel_execve(). However, that commit introduced the
wait_for_initramfs() synchronization hook which must be called from
the usermodehelper exec path right before the kernel_execve, in order
that request_module() et al done from *after* rootfs_initcall()
time (i.e. device_ and late_ initcalls) would continue to find a
populated initramfs as they used to.

Any call of wait_for_initramfs() done before the unpacking has been
scheduled (i.e. before rootfs_initcall time) mu...

This counter tracks the number of watches a user has, to compare against
the 'max_user_watches' limit. This causes a scalability bottleneck on
SPECjbb2015 on large systems as there is only one user. Changing to a
per-cpu counter increases throughput of the benchmark by about 30% on a
16-socket, > 1000 thread system.

[rdunlap@infradead.org: fix build errors in kernel/user.c when CONFIG_EPOLL=n]
[npiggin@gmail.com: move ifdefs into wrapper functions, slightly improve panic message]
  Link: https://lkml.kernel.org/r/1628051945.fens3r99ox.astroid@bobo.none
[akpm@linux-foundation.org: tweak user_epoll_alloc(), per Guenter]
  Link: https://lkml.kernel.org/r/20210804191421.GA1900577@roeck-us.net

Link: https://lkml.kernel.org/r/20210802032013.2751916-1-npiggin@gmail.com


Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reported-by: Anton Blanchard <anton@ozlabs.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The preferred git commit id reference has the form

	commit <SHA-1> ("Title line")

where SHA-1 is the commit hex hash with a minimum lenth of 12 and ("Title
line") is the complete title line of the commit with a (" prefix and ")
suffix.

The current tests fail when the "Title line" has one or more embedded
double quotes.

Improve the test that finds the commit SHA-1 hex hash then ("Title line")
by using $balanced_parens for a maximum of 3 consecutive lines.

[akpm@linux-foundation.org: add missing &&]

Link: https://lkml.kernel.org/r/976c6cdd680db4b55ae31b5fc2d1779da5c0dc66.camel@perches.com


Signed-off-by: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Denis Efremov <efremov@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Instead of checkpatch requiring the patch author to exactly match the
signed-off-by tag, commit 48ca2d8a ("checkpatch: add new warnings to
author signoff checks.") safely relaxed this requirement.

Although the local-part of an email address (local-part@domain), may be
case sensitive, exploiting the case sensitivity of mailbox local-parts
impedes interoperability and is discouraged.  Mailbox domains follow
normal DNS rules and are hence not case sensitive.  (Refer to
https://datatracker.ietf.org/doc/html/rfc5321#section-2.4.)

Further relax the patch author and signed-off-by tag comparison by making
the email address check case insensitive.

Link: https://lkml.kernel.org/r/20210816112725.173206-1-zohar@linux.ibm.com


Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Allow prefixing typical strings with L for wide strings and u for unicode
strings.

Link: https://lkml.kernel.org/r/20210801170733.1.I3f9784fd3c1007d08ec2e70b151d137687575495@changeid


Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Rename bitmap_alloc() to bitmap_zalloc() in tools to follow the bitmap API
in the kernel.

No functional changes intended.

Link: https://lkml.kernel.org/r/20210814211713.180533-14-yury.norov@gmail.com


Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Suggested-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Lobakin <alobakin@pm.me>
Cc: Alexey Klimov <aklimov@redhat.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fix all kernel-doc warnings in lib/iov_iter.c:

lib/iov_iter.c:695: warning: Function parameter or member 'i' not described in '_copy_mc_to_iter'
lib/iov_iter.c:695: warning: Excess function parameter 'iter' description in '_copy_mc_to_iter'
lib/iov_iter.c:695: warning: No description found for return value of '_copy_mc_to_iter'
lib/iov_iter.c:758: warning: Function parameter or member 'i' not described in '_copy_from_iter_flushcache'
lib/iov_iter.c:758: warning: Excess function parameter 'iter' description in '_copy_from_iter_flushcache'
lib/iov_iter.c:758: warning: No description found for return value of '_copy_from_iter_flushcache'

Link: https://lkml.kernel.org/r/20210809051053.6531-1-rdunlap@infradead.org


Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fix kernel-doc warnings in dump_stack.c:

lib/dump_stack.c:97: warning: Function parameter or member 'log_lvl' not described in 'dump_stack_lvl'
lib/dump_stack.c:97: warning: expecting prototype for dump_stack(). Prototype was for dump_stack_lvl() instead

Link: https://lkml.kernel.org/r/20210809051643.17567-1-rdunlap@infradead.org


Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This follows up commit ebd09577 ("lib/test: convert
lib/test_list_sort.c to use KUnit").

Converting this test to KUnit makes the test a bit shorter, standardizes
how it reports pass/fail, and adds an easier way to run the test [1].

Like ebd09577, this leaves the file and Kconfig option name the same,
but slightly changes their dependencies (needs CONFIG_KUNIT).

[1] Can be run via
$ ./tools/testing/kunit/kunit.py run --kunitconfig /dev/stdin <<EOF
CONFIG_KUNIT=y
CONFIG_TEST_SORT=y
EOF

[11:30:27] Starting KUnit Kernel ...
[11:30:30] ============================================================
[11:30:30] ======== [PASSED] lib_sort ========
[11:30:30] [PASSED] test_sort
[11:30:30] ============================================================
[11:30:30] Testing complete. 1 tests run. 0 failed. 0 crashed. 0 skipped.
[11:30:30] Elapsed time: 37.032s total, 0.001s configuring, 34.090s building, 0.000s running

Note: this is the time it took after a `make mrproper`.

With an incremental rebuild, this looks more like:
[11:38:58] Elapsed time: 6.444s total, 0.001s configuring, 3.416s building, 0.000s running

Since the test has no dependencies, it can also be run (with some other
tests) with just:
$ ./tools/testing/kunit/kunit.py run

Link: https://lkml.kernel.org/r/20210715232441.1380885-1-dlatypov@google.com


Signed-off-by: Daniel Latypov <dlatypov@google.com>
Cc: Pravin Shedge <pravin.shedge4linux@gmail.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>