Refactor __io_uring_register() by extracting a helper responsible for
ctx queisce. Looks better and will make it easier to add more
optimisations.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0339e0027504176be09237eefa7945bf9a6f153d.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Turns out we always init struct io_wait_queue in io_cqring_wait(), even
if it's not used after, i.e. there are already enough of CQEs. And often
it's exactly what happens, for instance, requests may have been
completed inline, or in case of io_uring_enter(submit=N, wait=1).

It shows up in my profiler, so optimise it by delaying the struct init.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6f1b81c60b947d165583dc333947869c3d85d037.1628471125.git.asml.silence@gmail.com
[axboe: fixed up for new cqring wait]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add more annotations for submission path functions holding ->uring_lock.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/128ec4185e26fbd661dd3a424aa66108ee8ff951.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

IOPOLL users should care more about getting completions for requests
they submitted, but not in "device did/completed something". Currently,
io_do_iopoll() may return a positive number, which will instruct
io_iopoll_check() to break the loop and end the syscall, even if there
is not enough CQEs or none at all.

Don't return positive numbers, so io_iopoll_check() exits only when it
gets an actual error, need reschedule or got enough CQEs.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/641a88f751623b6758303b3171f0a4141f06726e.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Replace the main if of io_flush_cached_reqs() with inverted condition +
goto, so all the cases are handled in the same way. And also extract
io_preinit_req() to make it cleaner and easier to refer to.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1abcba1f7b55dc53bf1dbe95036e345ffb1d5b01.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Prepare nodes that we're going to add before actually linking them, it's
always safer and costs us nothing.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f7e53f0c84c02ed6748c488ed0789b98f8cc6185.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

We prefer nornal task_works even if it would fail requests inside. Kill
a PF_EXITING check in io_req_task_work_add(), task_work_add() handles
well dying tasks, i.e. return error when can't enqueue due to late
stages of do_exit().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/fc14297e8441cd8f5d1743a2488cf0df09bf48ac.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Move io-wq callbacks closer to each other, so it's easier to work with
them, and rename io_free_work() into io_wq_free_work() for consistency.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/851bbc7f0f86f206d8c1333efee8bcb9c26e419f.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

If we use fixed files, we can be sure (almost) that REQ_F_ISREG is set.
However, for non-reg files io_prep_rw() still will look into inode to
double check, and that's expensive and can be avoided.

The only caveat is that it only currently works with 64+ bit
architectures, see FFS_ISREG, so we should consider that.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0a62780c491ca2522cd52db4ae3f16e03aafed0f.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_file_supports_async() checks whether a file supports nowait
operations, so "async" in the name is misleading. Rename it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/33d55b5ce43aa1884c637c1957f1e30d30dc3bec.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Optimise io_file_get() with registered files, which is in a hot path,
by inlining parts of the function. Saves a function call, and
inefficiencies of passing arguments, e.g. evaluating
(sqe_flags & IOSQE_FIXED_FILE).

It couldn't have been done before as compilers were refusing to inline
it because of the function size.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/52115cd6ce28f33bd0923149c0e6cb611084a0b1.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Instead of hand-coded two-level tables for registered files, allocate
them with kvmalloc(). In many cases small enough tables are enough, and
so can be kmalloc()'ed removing an extra memory load and a bunch of bit
logic instructions from the hot path. If the table is larger, we trade
off all the pros with a TLB-assisted memory lookup.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/280421d3b48775dabab773006bb5588c7b2dabc0.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Currently we only wake the first waiter, even if we have enough entries
posted to satisfy multiple waiters. Improve that situation so that
every waiter knows how much the CQ tail has to advance before they can
be safely woken up.

With this change, if we have N waiters each asking for 1 event and we get
4 completions, then we wake up 4 waiters. If we have N waiters asking
for 2 completions and we get 4 completions, then we wake up the first
two. Previously, only the first waiter would've been woken up.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Daniel reports that the v5.14-rc4-rt4 kernel throws a BUG when running
stress-ng:

| [   90.202543] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:35
| [   90.202549] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 2047, name: iou-wrk-2041
| [   90.202555] CPU: 5 PID: 2047 Comm: iou-wrk-2041 Tainted: G        W         5.14.0-rc4-rt4+ #89
| [   90.202559] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
| [   90.202561] Call Trace:
| [   90.202577]  dump_stack_lvl+0x34/0x44
| [   90.202584]  ___might_sleep.cold+0x87/0x94
| [   90.202588]  rt_spin_lock+0x19/0x70
| [   90.202593]  ___slab_alloc+0xcb/0x7d0
| [   90.202598]  ? newidle_balance.constprop.0+0xf5/0x3b0
| [   90.202603]  ? dequeue_entity+0xc3/0x290
| [   90.202605]  ? io_wqe_dec_running.isra.0+0x98/0xe0
| [   90.202610]  ? pick_next_task_fair+0xb9/0x330
| [   90.202612]  ? __schedule+0x670/0x1410
| [   90.202615]  ? io_wqe_dec_running.isra.0+0x98/0xe0
| [   90.202618]  kmem_cache_alloc_trace+0x79/0x1f0
| [   90.202621]  io_wqe_dec_running.isra.0+0x98/0xe0
| [   90.202625]  io_wq_worker_sleeping+0x37/0x50
| [   90.202628]  schedule+0x30/0xd0
| [   90.202630]  schedule_timeout+0x8f/0x1a0
| [   90.202634]  ? __bpf_trace_tick_stop+0x10/0x10
| [   90.202637]  io_wqe_worker+0xfd/0x320
| [   90.202641]  ? finish_task_switch.isra.0+0xd3/0x290
| [   90.202644]  ? io_worker_handle_work+0x670/0x670
| [   90.202646]  ? io_worker_handle_work+0x670/0x670
| [   90.202649]  ret_from_fork+0x22/0x30

which is due to the RT kernel not liking a GFP_ATOMIC allocation inside
a raw spinlock. Besides that not working on RT, doing any kind of
allocation from inside schedule() is kind of nasty and should be avoided
if at all possible.

This particular path happens when an io-wq worker goes to sleep, and we
need a new worker to handle pending work. We currently allocate a small
data item to hold the information we need to create a new worker, but we
can instead include this data in the io_worker struct itself and just
protect it with a single bit lock. We only really need one per worker
anyway, as we will have run pending work between to sleep cycles.

https://lore.kernel.org/lkml/20210804082418.fbibprcwtzyt5qax@beryllium.lan/Reported-by: Daniel Wagner <dwagner@suse.de>
Tested-by: Daniel Wagner <dwagner@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull powerpc fixes from Michael Ellerman:

 - Fix random crashes on some 32-bit CPUs by adding isync() after
   locking/unlocking KUEP

 - Fix intermittent crashes when loading modules with strict module RWX

 - Fix a section mismatch introduce by a previous fix.

Thanks to Christophe Leroy, Fabiano Rosas, Laurent Vivier, Murilo
Opsfelder Araújo, Nathan Chancellor, and Stan Johnson.

h# -----BEGIN PGP SIGNATURE-----

* tag 'powerpc-5.14-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/mm: Fix set_memory_*() against concurrent accesses
  powerpc/32s: Fix random crashes by adding isync() after locking/unlocking KUEP
  powerpc/xive: Do not mark xive_request_ipi() as __init

Pull clk driver fixes from Stephen Boyd:

 - Make the regulator state match the GDSC power domain state at boot on
   Qualcomm SoCs so that the regulator isn't turned off inadvertently.

 - Fix earlycon on i.MX6Q SoCs

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: qcom: gdsc: Ensure regulator init state matches GDSC state
  clk: imx6q: fix uart earlycon unwork

Pull char/misc driver fixes from Greg KH:
 "Here are some small driver fixes for 5.14-rc7.

  They consist of:

   - revert for an interconnect patch that was found to have problems

   - ipack tpci200 driver fixes for reported problems

   - slimbus messaging and ngd fixes for reported problems

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

* tag 'char-misc-5.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  ipack: tpci200: fix memory leak in the tpci200_register
  ipack: tpci200: fix many double free issues in tpci200_pci_probe
  slimbus: ngd: reset dma setup during runtime pm
  slimbus: ngd: set correct device for pm
  slimbus: messaging: check for valid transaction id
  slimbus: messaging: start transaction ids from 1 instead of zero
  Revert "interconnect: qcom: icc-rpmh: Add BCMs to commit list in pre_aggregate"

Pull USB fix from Greg KH:
 "Here is a single USB typec tcpm fix for a reported problem for
  5.14-rc7. It showed up in 5.13 and resolves an issue that Hans found.
  It has been in linux-next this week with no reported problems"

* tag 'usb-5.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: typec: tcpm: Fix VDMs sometimes not being forwarded to alt-mode drivers

Pull RISC-V fixes from Palmer Dabbelt:

 - fix the sifive-l2-cache device tree bindings for json-schema
   compatibility. This does not change the intended behavior of the
   binding.

 - avoid improperly freeing necessary resources during early boot.

* tag 'riscv-for-linus-5.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Fix a number of free'd resources in init_resources()
  dt-bindings: sifive-l2-cache: Fix 'select' matching

Pull s390 fix from Vasily Gorbik:

 - fix use after free of zpci_dev in pci code

* tag 's390-5.14-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/pci: fix use after free of zpci_dev

Pull mandatory file locking deprecation warning from Jeff Layton:
 "As discussed on the list, this patch just adds a new warning for folks
  who still have mandatory locking enabled and actually mount with '-o
  mand'. I'd like to get this in for v5.14 so we can push this out into
  stable kernels and hopefully reach folks who have mounts with -o mand.

  For now, I'm operating under the assumption that we'll fully remove
  this support in v5.15, but we can move that out if any legitimate
  users of this facility speak up between now and then"

* tag 'locks-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  fs: warn about impending deprecation of mandatory locks

Pull block fixes from Jens Axboe:
 "Three fixes from Ming Lei that should go into 5.14:

   - Fix for a kernel panic when iterating over tags for some cases
     where a flush request is present, a regression in this cycle.

   - Request timeout fix

   - Fix flush request checking"

* tag 'block-5.14-2021-08-20' of git://git.kernel.dk/linux-block:
  blk-mq: fix is_flush_rq
  blk-mq: fix kernel panic during iterating over flush request
  blk-mq: don't grab rq's refcount in blk_mq_check_expired()

Pull io_uring fixes from Jens Axboe:
 "A few small fixes that should go into this release:

   - Fix never re-assigning an initial error value for io_uring_enter()
     for SQPOLL, if asked to do nothing

   - Fix xa_alloc_cycle() return value checking, for cases where we have
     wrapped around

   - Fix for a ctx pin issue introduced in this cycle (Pavel)"

* tag 'io_uring-5.14-2021-08-20' of git://git.kernel.dk/linux-block:
  io_uring: fix xa_alloc_cycle() error return value check
  io_uring: pin ctx on fallback execution
  io_uring: only assign io_uring_enter() SQPOLL error in actual error case

We've had CONFIG_MANDATORY_FILE_LOCKING since 2015 and a lot of distros
have disabled it. Warn the stragglers that still use "-o mand" that
we'll be dropping support for that mount option.

Cc: stable@vger.kernel.org
Signed-off-by: Jeff Layton <jlayton@kernel.org>

We currently check for ret != 0 to indicate error, but '1' is a valid
return and just indicates that the allocation succeeded with a wrap.
Correct the check to be for < 0, like it was before the xarray
conversion.

Cc: stable@vger.kernel.org
Fixes: 61cf9370 ("io_uring: Convert personality_idr to XArray")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull ACPI fixes from Rafael Wysocki:
 "These fix two mistakes in new code.

  Specifics:

   - Prevent confusing messages from being printed if the PRMT table is
     not present or there are no PRM modules (Aubrey Li).

   - Fix the handling of suspend-to-idle entry and exit in the case when
     the Microsoft UUID is used with the Low-Power S0 Idle _DSM
     interface (Mario Limonciello)"

* tag 'acpi-5.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: PM: s2idle: Invert Microsoft UUID entry and exit
  ACPI: PRM: Deal with table not present or no module found

Pull power management fixes from Rafael Wysocki:
 "These fix some issues in the ARM cpufreq drivers and in the operating
  performance points (OPP) framework.

  Specifics:

   - Fix useless WARN() in the OPP core and prevent a noisy warning
     from being printed by OPP _put functions (Dmitry Osipenko).

   - Fix error path when allocation failed in the arm_scmi cpufreq
     driver (Lukasz Luba).

   - Blacklist Qualcomm sc8180x and Qualcomm sm8150 in
     cpufreq-dt-platdev (Bjorn Andersson, Thara Gopinath).

   - Forbid cpufreq for 1.2 GHz variant in the armada-37xx cpufreq
     driver (Marek Behún)"

* tag 'pm-5.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  opp: Drop empty-table checks from _put functions
  cpufreq: armada-37xx: forbid cpufreq for 1.2 GHz variant
  cpufreq: blocklist Qualcomm sm8150 in cpufreq-dt-platdev
  cpufreq: arm_scmi: Fix error path when allocation failed
  opp: remove WARN when no valid OPPs remain
  cpufreq: blacklist Qualcomm sc8180x in cpufreq-dt-platdev

Merge misc fixes from Andrew Morton:
 "10 patches.

  Subsystems affected by this patch series: MAINTAINERS and mm (shmem,
  pagealloc, tracing, memcg, memory-failure, vmscan, kfence, and
  hugetlb)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  hugetlb: don't pass page cache pages to restore_reserve_on_error
  kfence: fix is_kfence_address() for addresses below KFENCE_POOL_SIZE
  mm: vmscan: fix missing psi annotation for node_reclaim()
  mm/hwpoison: retry with shake_page() for unhandlable pages
  mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim
  MAINTAINERS: update ClangBuiltLinux IRC chat
  mmflags.h: add missing __GFP_ZEROTAGS and __GFP_SKIP_KASAN_POISON names
  mm/page_alloc: don't corrupt pcppage_migratetype
  Revert "mm: swap: check if swap backing device is congested or not"
  Revert "mm/shmem: fix shmem_swapin() race with swapoff"

Pull drm fixes from Dave Airlie:
 "Regularly scheduled fixes. The ttm one solves a problem of GPU drivers
  failing to load if debugfs is off in Kconfig, otherwise the i915 and
  mediatek, and amdgpu fixes all fairly normal.

  Nouveau has a couple of display fixes, but it has a fix for a
  longstanding race condition in it's memory manager code, and the fix
  mostly removes some code that wasn't working properly and has no
  userspace users. This fix makes the diffstat kinda larger but in a
  good (negative line-count) way.

  core:
   - fix drm_wait_vblank uapi copying bug

  ttm:
   - fix debugfs init when debugfs is off

  amdgpu:
   - vega10 SMU workload fix
   - DCN VM fix
   - DCN 3.01 watermark fix

  amdkfd:
   - SVM fix

  nouveau:
   - ampere display fixes
   - remove MM misfeature to fix a longstanding race condition

  i915:
   - tweaked display workaround for all PCHs
   - eDP MSO pipe sanity for ADL-P fix
   - remove unused symbol export

  mediatek:
   - AAL output size setting
   - Delete component in remove function"

* tag 'drm-fixes-2021-08-20-3' of git://anongit.freedesktop.org/drm/drm:
  drm/amd/display: Use DCN30 watermark calc for DCN301
  drm/i915/dp: remove superfluous EXPORT_SYMBOL()
  drm/i915/edp: fix eDP MSO pipe sanity checks for ADL-P
  drm/i915: Tweaked Wa_14010685332 for all PCHs
  drm/nouveau: rip out nvkm_client.super
  drm/nouveau: block a bunch of classes from userspace
  drm/nouveau/fifo/nv50-: rip out dma channels
  drm/nouveau/kms/nv50: workaround EFI GOP window channel format differences
  drm/nouveau/disp: power down unused DP links during init
  drm/nouveau: recognise GA107
  drm: Copy drm_wait_vblank to user before returning
  drm/amd/display: Ensure DCN save after VM setup
  drm/amdkfd: fix random KFDSVMRangeTest.SetGetAttributesTest test failure
  drm/amd/pm: change the workload type for some cards
  Revert "drm/amd/pm: fix workload mismatch on vega10"
  drm: ttm: Don't bail from ttm_global_init if debugfs_create_dir fails
  drm/mediatek: Add component_del in OVL and COLOR remove function
  drm/mediatek: Add AAL output size configuration

Pull PCI fixes from Bjorn Helgaas:

 - Add Rahul Tanwar as Intel LGM Gateway PCIe maintainer (Rahul Tanwar)

 - Add Jim Quinlan et al as Broadcom STB PCIe maintainers (Jim Quinlan)

 - Increase D3hot-to-D0 delay for AMD Renoir/Cezanne XHCI (Marcin
   Bachry)

 - Correct iomem_get_mapping() usage for legacy_mem sysfs (Krzysztof
   Wilczyński)

* tag 'pci-v5.14-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI/sysfs: Use correct variable for the legacy_mem sysfs object
  PCI: Increase D3 delay for AMD Renoir/Cezanne XHCI
  MAINTAINERS: Add Jim Quinlan et al as Broadcom STB PCIe maintainers
  MAINTAINERS: Add Rahul Tanwar as Intel LGM Gateway PCIe maintainer

Pull MMC host fixes from Ulf Hansson:

 - dw_mmc: Fix hang on data CRC error

 - mmci: Fix voltage switch procedure for the stm32 variant

 - sdhci-iproc: Fix some clock issues for BCM2711

 - sdhci-msm: Fixup software timeout value

* tag 'mmc-v5.14-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: sdhci-iproc: Set SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN on BCM2711
  mmc: sdhci-iproc: Cap min clock frequency on BCM2711
  mmc: sdhci-msm: Update the software timeout value for sdhc
  mmc: mmci: stm32: Check when the voltage switch procedure should be done
  mmc: dw_mmc: Fix hang on data CRC error

Pull more sound fixes from Takashi Iwai:
 "This is a quick follow up for 5.14: a fix for a very recently
  introduced regression on ASoC Intel Atom driver, and another trivial
  HD-audio quirk for HP laptops"

* tag 'sound-5.14-rc7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ASoC: intel: atom: Fix breakage for PCM buffer address setup
  ALSA: hda/realtek: Limit mic boost on HP ProBook 445 G8

Pull arm64 fixes from Will Deacon:

 - Fix cleaning of vDSO directories

 - Ensure CNTHCTL_EL2 is fully initialised when booting at EL2

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: initialize all of CNTHCTL_EL2
  arm64: clean vdso & vdso32 files

* acpi-pm:
  ACPI: PM: s2idle: Invert Microsoft UUID entry and exit

Pull iommu fixes from Joerg Roedel:

 - Fix for a potential NULL-ptr dereference in IOMMU core code

 - Two resource leak fixes

 - Cache flush fix in the Intel VT-d driver

* tag 'iommu-fixes-v5.14-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/vt-d: Fix incomplete cache flush in intel_pasid_tear_down_entry()
  iommu/vt-d: Fix PASID reference leak
  iommu: Check if group is NULL before remove device
  iommu/dma: Fix leak in non-contiguous API

* pm-opp:
  opp: Drop empty-table checks from _put functions
  opp: remove WARN when no valid OPPs remain

syzbot hit kernel BUG at fs/hugetlbfs/inode.c:532 as described in [1].
This BUG triggers if the HPageRestoreReserve flag is set on a page in
the page cache.  It should never be set, as the routine
huge_add_to_page_cache explicitly clears the flag after adding a page to
the cache.

The only code other than huge page allocation which sets the flag is
restore_reserve_on_error.  It will potentially set the flag in rare out
of memory conditions.  syzbot was injecting errors to cause memory
allocation errors which exercised this specific path.

The code in restore_reserve_on_error is doing the right thing.  However,
there are instances where pages in the page cache were being passed to
restore_reserve_on_error.  This is incorrect, as once a page goes into
the cache reservation information will not be modified for the page
until it is removed from the cache.  Error paths do not remove pages
from the cache, so even in the case of error, the page will remain in
the cache and no reservation adjustment is needed.

Modify routines that potentially call restore_reserve_on_error with a
page cache page to no longer do so.

Note on fixes tag: Prior to commit 846be085 ("mm/hugetlb: expand
restore_reserve_on_error functionality") the routine would not process
page cache pages because the HPageRestoreReserve flag is not set on such
pages.  Therefore, this issue could not be trigggered.  The code added
by commit 846be085 ("mm/hugetlb: expand restore_reserve_on_error
functionality") is needed and correct.  It exposed incorrect calls to
restore_reserve_on_error which is the root cause addressed by this
commit.

[1] https://lore.kernel.org/linux-mm/00000000000050776d05c9b7c7f0@google.com/

Link: https://lkml.kernel.org/r/20210818213304.37038-1-mike.kravetz@oracle.com
Fixes: 846be085 ("mm/hugetlb: expand restore_reserve_on_error functionality")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reported-by: <syzbot+67654e51e54455f1c585@syzkaller.appspotmail.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Originally the addr != NULL check was meant to take care of the case
where __kfence_pool == NULL (KFENCE is disabled).  However, this does
not work for addresses where addr > 0 && addr < KFENCE_POOL_SIZE.

This can be the case on NULL-deref where addr > 0 && addr < PAGE_SIZE or
any other faulting access with addr < KFENCE_POOL_SIZE.  While the
kernel would likely crash, the stack traces and report might be
confusing due to double faults upon KFENCE's attempt to unprotect such
an address.

Fix it by just checking that __kfence_pool != NULL instead.

Link: https://lkml.kernel.org/r/20210818130300.2482437-1-elver@google.com
Fixes: 0ce20dd8 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Marco Elver <elver@google.com>
Reported-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>    [5.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In a debugging session the other day, Rik noticed that node_reclaim()
was missing memstall annotations.  This means we'll miss pressure and
lost productivity resulting from reclaim on an overloaded local NUMA
node when vm.zone_reclaim_mode is enabled.

There haven't been any reports, but that's likely because
vm.zone_reclaim_mode hasn't been a commonly used feature recently, and
the intersection between such setups and psi users is probably nil.

But secondary memory such as CXL-connected DIMMS, persistent memory etc,
and the page demotion patches that handle them
(https://lore.kernel.org/lkml/20210401183216.443C4443@viggo.jf.intel.com/)
could soon make this a more common codepath again.

Link: https://lkml.kernel.org/r/20210818152457.35846-1-hannes@cmpxchg.orgSigned-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>