Before this patch, sister functions gfs2_make_fs_rw and gfs2_make_fs_ro locked
(held) the freeze glock by calling gfs2_freeze_lock and gfs2_freeze_unlock.
The problem is, not all the callers of gfs2_make_fs_ro should be doing this.
The three callers of gfs2_make_fs_ro are: remount (gfs2_reconfigure),
signal_our_withdraw, and unmount (gfs2_put_super). But when unmounting the
file system we can get into the following circular lock dependency:

deactivate_super
   down_write(&s->s_umount); <-------------------------------------- s_umount
   deactivate_locked_super
      gfs2_kill_sb
         kill_block_super
            generic_shutdown_super
               gfs2_put_super
                  gfs2_make_fs_ro
                     gfs2_glock_nq_init sd_freeze_gl
                        freeze_go_sync
                           if (freeze glock in SH)
                              freeze_super (vfs)
                                 down_write(&sb->s_umount); <------- s_umount

This patch moves the hold of the freeze glock outside the two sister rw/ro
functions to their callers, but it doesn't request the glock from
gfs2_put_super, thus eliminating the circular dependency.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Many places in the gfs2 code queued and dequeued the freeze glock.
Almost all of them acquire it in SHARED mode, and need to specify the
same LM_FLAG_NOEXP and GL_EXACT flags.

This patch adds common helper functions gfs2_freeze_lock and gfs2_freeze_unlock
to make the code more readable, and to prepare for the next patch.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Pull gfs2 updates from Andreas Gruenbacher:

 - Don't wait for unfreeze of the wrong filesystems

 - Remove an obsolete delete_work_func hack and an incorrect
   sb_start_write

 - Minor documentation updates and cosmetic care

* tag 'gfs2-for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: in signal_our_withdraw wait for unfreeze of _this_ fs only
  gfs2: Remove sb_start_write from gfs2_statfs_sync
  gfs2: remove trailing semicolons from macro definitions
  Revert "GFS2: Prevent delete work from occurring on glocks used for create"
  gfs2: Make inode operations static
  MAINTAINERS: Add gfs2 bug tracker link
  Documentation: Update filesystems/gfs2.rst

Commit b0a0c261 ("epoll: wire up syscall epoll_pwait2") wired up
the 64 bit syscall instead of the compat variant in a couple of places.

Fixes: b0a0c261 ("epoll: wire up syscall epoll_pwait2")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'close-range-cloexec-unshare-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull close_range fix from Christian Brauner:
 "syzbot reported a bug when asking close_range() to unshare the file
  descriptor table and making all fds close-on-exec.

  If CLOSE_RANGE_UNSHARE the caller will receive a private file
  descriptor table in case their file descriptor table is currently
  shared before operating on the requested file descriptor range.

  For the case where the caller has requested all file descriptors to be
  actually closed via e.g. close_range(3, ~0U, CLOSE_RANGE_UNSHARE) the
  kernel knows that the caller does not need any of the file descriptors
  anymore and will optimize the close operation by only copying all
  files in the range from 0 to 3 and no others.

  However, if the caller requested CLOSE_RANGE_CLOEXEC together with
  CLOSE_RANGE_UNSHARE the caller wants to still make use of the file
  descriptors so the kernel needs to copy all of them and can't
  optimize.

  The original patch didn't account for this and thus could cause oopses
  as evidenced by the syzbot report because it assumed that all fds had
  been copied. Fix this by handling the CLOSE_RANGE_CLOEXEC case and
  copying all fds if the two flags are specified together.

  This should've been caught in the selftests but the original patch
  didn't cover this case and I didn't catch it during review. So in
  addition to the bugfix I'm also adding selftests. They will reliably
  reproduce the bug on a non-fixed kernel and allows us to catch
  regressions and verify correct behavior.

  Note, the kernel selftest tree contained a bunch of changes that made
  the original selftest fail to compile so there are small fixups in
  here make them compile without warnings"

* tag 'close-range-cloexec-unshare-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  selftests/core: add regression test for CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC
  selftests/core: add test for CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC
  selftests/core: handle missing syscall number for close_range
  selftests/core: fix close_range_test build after XFAIL removal
  close_range: unshare all fds for CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC

Pull more xen updates from Juergen Gross:
 "Some minor cleanup patches and a small series disentangling some Xen
  related Kconfig options"

* tag 'for-linus-5.11-rc1b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: Kconfig: remove X86_64 depends from XEN_512GB
  xen/manage: Fix fall-through warnings for Clang
  xen-blkfront: Fix fall-through warnings for Clang
  xen: remove trailing semicolon in macro definition
  xen: Kconfig: nest Xen guest options
  xen: Remove Xen PVH/PVHVM dependency on PCI
  x86/xen: Convert to DEFINE_SHOW_ATTRIBUTE

Pull pcmcia updates from Dominik Brodowski:
 "Besides a few PCMCIA odd fixes, the NEC VRC4173 CARDU driver is
  removed, as it has not compiled in ages"

* 'pcmcia-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux:
  pcmcia: omap: Fix error return code in omap_cf_probe()
  pcmcia: Remove NEC VRC4173 CARDU
  pcmcia: db1xxx_ss: remove unneeded semicolon
  pcmcia/electra_cf: Fix some return values in 'electra_cf_probe()' in case of error

Pull i3c updates from Boris Brezillon:

 - Add the HCI driver

 - Add a missing destroy_workqueue() in an error path

 - Flag Alexandre Belloni as the new maintainer

* tag 'i3c/for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux:
  i3c/master/mipi-i3c-hci: quiet maybe-unused variable warning
  i3c: Resign from my maintainer role
  i3c/master: Fix uninitialized variable next_addr
  i3c/master: introduce the mipi-i3c-hci driver
  dt-bindings: i3c: MIPI I3C Host Controller Interface
  i3c master: fix missing destroy_workqueue() on error in i3c_master_register

Pull power supply and reset updates from Sebastian Reichel:
 "Battery/charger driver changes:

   - collie_battery, generic-adc-battery, s3c-adc-battery: convert to
     GPIO descriptors (incl ARM board files)

   - misc cleanup and fixes

  Reset drivers:

   - new poweroff driver for force disabling a regulator

   - use printk format symbol resolver

   - ocelot: add support for Luton and Jaguar2"

* tag 'for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supply: (31 commits)
  power: supply: Fix a typo in warning message
  Documentation: DT: binding documentation for regulator-poweroff
  power: reset: new driver regulator-poweroff
  power: supply: ab8500: Use dev_err_probe() for IIO channels
  power: supply: ab8500_fg: Request all IRQs as threaded
  power: supply: ab8500_charger: Oneshot threaded IRQs
  power: supply: ab8500: Convert to dev_pm_ops
  power: supply: ab8500: Use local helper
  power: supply: wm831x_power: remove unneeded break
  power: supply: bq24735: Drop unused include
  power: supply: bq24190_charger: Drop unused include
  power: supply: generic-adc-battery: Use GPIO descriptors
  power: supply: collie_battery: Convert to GPIO descriptors
  power: supply: bq24190_charger: fix reference leak
  power: supply: s3c-adc-battery: Convert to GPIO descriptors
  power: reset: Use printk format symbol resolver
  power: supply: axp20x_usb_power: Use power efficient workqueue for debounce
  power: supply: axp20x_usb_power: fix typo
  power: supply: max8997-charger: Improve getting charger status
  power: supply: max8997-charger: Fix platform data retrieval
  ...

Pull HSI updates from Sebastian Reichel:
 "Misc cleanups"

* tag 'hsi-for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-hsi:
  HSI: core: fix a kernel-doc markup
  HSI: omap_ssi: Don't jump to free ID in ssi_add_controller()

Merge tag 'pwm/for-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm

Pull pwm updates from Thierry Reding:
 "This is a fairly big release cycle from the PWM framework's point of
  view.

  There's a large patcheset here which converts drivers to use the new
  devm_platform_ioremap_resource() helper and a bunch of minor fixes to
  existing drivers. Some of the existing drivers also add support for
  more hardware, such as Atmel SAMA 5D2 and Mediatek MT8183.

  Finally there's a couple of new drivers for Intel Keem Bay and LGM
  SoCs as well as the DesignWare PWM controller"

* tag 'pwm/for-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: (66 commits)
  pwm: sun4i: Remove erroneous else branch
  pwm: sl28cpld: Set driver data before registering the PWM chip
  pwm: Remove unused function pwmchip_add_inversed()
  pwm: imx27: Fix overflow for bigger periods
  pwm: bcm2835: Support apply function for atomic configuration
  pwm: keembay: Fix build failure with -Os
  pwm: core: Use octal permission
  pwm: lpss: Make compilable with COMPILE_TEST
  pwm: Fix dependencies on HAS_IOMEM
  pwm: Use -EINVAL for unsupported polarity
  pwm: sti: Remove unnecessary blank line
  pwm: sti: Avoid conditional gotos
  pwm: Add PWM fan controller driver for LGM SoC
  Add DT bindings YAML schema for PWM fan controller of LGM SoC
  pwm: Add DesignWare PWM Controller Driver
  dt-bindings: pwm: mtk-disp: add MT8167 SoC binding
  pwm: mediatek: Add MT8183 SoC support
  pwm: mediatek: Always use bus clock
  dt-bindings: pwm: pwm-mediatek: Add documentation for MT8183 SoC
  pwm: Add PWM driver for Intel Keem Bay
  ...

Merge still more updates from Andrew Morton:
 "18 patches.

  Subsystems affected by this patch series: mm (memcg and cleanups) and
  epoll"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm/Kconfig: fix spelling mistake "whats" -> "what's"
  selftests/filesystems: expand epoll with epoll_pwait2
  epoll: wire up syscall epoll_pwait2
  epoll: add syscall epoll_pwait2
  epoll: convert internal api to timespec64
  epoll: eliminate unnecessary lock for zero timeout
  epoll: replace gotos with a proper loop
  epoll: pull all code between fetch_events and send_event into the loop
  epoll: simplify and optimize busy loop logic
  epoll: move eavail next to the list_empty_careful check
  epoll: pull fatal signal checks into ep_send_events()
  epoll: simplify signal handling
  epoll: check for events when removing a timed out thread from the wait queue
  mm/memcontrol:rewrite mem_cgroup_page_lruvec()
  mm, kvm: account kvm_vcpu_mmap to kmemcg
  mm/memcg: remove unused definitions
  mm/memcg: warning on !memcg after readahead page charged
  mm/memcg: bail early from swap accounting if memcg disabled

There is a spelling mistake in the Kconfig help text. Fix it.

Link: https://lkml.kernel.org/r/20201217172717.58203-1-colin.king@canonical.comSigned-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Code coverage for the epoll_pwait2 syscall.

epoll62: Repeat basic test epoll1, but exercising the new syscall.
epoll63: Pass a timespec and exercise the timeout wakeup path.

Link: https://lkml.kernel.org/r/20201121144401.3727659-5-willemdebruijn.kernel@gmail.comSigned-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
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>

Split off from prev patch in the series that implements the syscall.

Link: https://lkml.kernel.org/r/20201121144401.3727659-4-willemdebruijn.kernel@gmail.comSigned-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
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>

Add syscall epoll_pwait2, an epoll_wait variant with nsec resolution that
replaces int timeout with struct timespec.  It is equivalent otherwise.

    int epoll_pwait2(int fd, struct epoll_event *events,
                     int maxevents,
                     const struct timespec *timeout,
                     const sigset_t *sigset);

The underlying hrtimer is already programmed with nsec resolution.
pselect and ppoll also set nsec resolution timeout with timespec.

The sigset_t in epoll_pwait has a compat variant. epoll_pwait2 needs
the same.

For timespec, only support this new interface on 2038 aware platforms
that define __kernel_timespec_t. So no CONFIG_COMPAT_32BIT_TIME.

Link: https://lkml.kernel.org/r/20201121144401.3727659-3-willemdebruijn.kernel@gmail.comSigned-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
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>

Patch series "add epoll_pwait2 syscall", v4.

Enable nanosecond timeouts for epoll.

Analogous to pselect and ppoll, introduce an epoll_wait syscall
variant that takes a struct timespec instead of int timeout.

This patch (of 4):

Make epoll more consistent with select/poll: pass along the timeout as
timespec64 pointer.

In anticipation of additional changes affecting all three polling
mechanisms:

- add epoll_pwait2 syscall with timespec semantics,
  and share poll_select_set_timeout implementation.
- compute slack before conversion to absolute time,
  to save one ktime_get_ts64 call.

Link: https://lkml.kernel.org/r/20201121144401.3727659-1-willemdebruijn.kernel@gmail.com
Link: https://lkml.kernel.org/r/20201121144401.3727659-2-willemdebruijn.kernel@gmail.comSigned-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We call ep_events_available() under lock when timeout is 0, and then call
it without locks in the loop for the other cases.

Instead, call ep_events_available() without lock for all cases.  For
non-zero timeouts, we will recheck after adding the thread to the wait
queue.  For zero timeout cases, by definition, user is opportunistically
polling and will have to call epoll_wait again in the future.

Note that this lock was kept in c5a282e9 because the whole loop was
historically under lock.

This patch results in a 1% CPU/RPC reduction in RPC benchmarks.

Link: https://lkml.kernel.org/r/20201106231635.3528496-9-soheil.kdev@gmail.comSigned-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The existing loop is pointless, and the labels make it really hard to
follow the structure.

Replace that control structure with a simple loop that returns when there
are new events, there is a signal, or the thread has timed out.

Link: https://lkml.kernel.org/r/20201106231635.3528496-8-soheil.kdev@gmail.comSigned-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This is a no-op change which simplifies the follow up patches.

Link: https://lkml.kernel.org/r/20201106231635.3528496-7-soheil.kdev@gmail.comSigned-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ep_events_available() is called multiple times around the busy loop logic,
even though the logic is generally not used.  ep_reset_busy_poll_napi_id()
is similarly always called, even when busy loop is not used.

Eliminate ep_reset_busy_poll_napi_id() and inline it inside
ep_busy_loop().  Make ep_busy_loop() return whether there are any events
available after the busy loop.  This will eliminate unnecessary loads and
branches, and simplifies the loop.

Link: https://lkml.kernel.org/r/20201106231635.3528496-6-soheil.kdev@gmail.comSigned-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This is a no-op change and simply to make the code more coherent.

Link: https://lkml.kernel.org/r/20201106231635.3528496-5-soheil.kdev@gmail.comSigned-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

To simplify the code, pull in checking the fatal signals into
ep_send_events().  ep_send_events() is called only from ep_poll().

Note that, previously, we were always checking fatal events, but it is
checked only if eavail is true.  This should be fine because the goal of
that check is to quickly return from epoll_wait() when there is a pending
fatal signal.

Link: https://lkml.kernel.org/r/20201106231635.3528496-4-soheil.kdev@gmail.comSigned-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Check signals before locking ep->lock, and immediately return -EINTR if
there is any signal pending.

This saves a few loads, stores, and branches from the hot path and
simplifies the loop structure for follow up patches.

Link: https://lkml.kernel.org/r/20201106231635.3528496-3-soheil.kdev@gmail.comSigned-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "simplify ep_poll".

This patch series is a followup based on the suggestions and feedback by
Linus:
https://lkml.kernel.org/r/CAHk-=wizk=OxUyQPbO8MS41w2Pag1kniUV5WdD5qWL-gq1kjDA@mail.gmail.com

The first patch in the series is a fix for the epoll race in presence of
timeouts, so that it can be cleanly backported to all affected stable
kernels.

The rest of the patch series simplify the ep_poll() implementation.  Some
of these simplifications result in minor performance enhancements as well.
We have kept these changes under self tests and internal benchmarks for a
few days, and there are minor (1-2%) performance enhancements as a result.

This patch (of 8):

After abc610e0 ("fs/epoll: avoid barrier after an epoll_wait(2)
timeout"), we break out of the ep_poll loop upon timeout, without checking
whether there is any new events available.  Prior to that patch-series we
always called ep_events_available() after exiting the loop.

This can cause races and missed wakeups.  For example, consider the
following scenario reported by Guantao Liu:

Suppose we have an eventfd added using EPOLLET to an epollfd.

Thread 1: Sleeps for just below 5ms and then writes to an eventfd.
Thread 2: Calls epoll_wait with a timeout of 5 ms. If it sees an
          event of the eventfd, it will write back on that fd.
Thread 3: Calls epoll_wait with a negative timeout.

Prior to abc610e0, it is guaranteed that Thread 3 will wake up either
by Thread 1 or Thread 2.  After abc610e0, Thread 3 can be blocked
indefinitely if Thread 2 sees a timeout right before the write to the
eventfd by Thread 1.  Thread 2 will be woken up from
schedule_hrtimeout_range and, with evail 0, it will not call
ep_send_events().

To fix this issue:
1) Simplify the timed_out case as suggested by Linus.
2) while holding the lock, recheck whether the thread was woken up
   after its time out has reached.

Note that (2) is different from Linus' original suggestion: It do not set
"eavail = ep_events_available(ep)" to avoid unnecessary contention (when
there are too many timed-out threads and a small number of events), as
well as races mentioned in the discussion thread.

This is the first patch in the series so that the backport to stable
releases is straightforward.

Link: https://lkml.kernel.org/r/20201106231635.3528496-1-soheil.kdev@gmail.com
Link: https://lkml.kernel.org/r/CAHk-=wizk=OxUyQPbO8MS41w2Pag1kniUV5WdD5qWL-gq1kjDA@mail.gmail.com
Link: https://lkml.kernel.org/r/20201106231635.3528496-2-soheil.kdev@gmail.com
Fixes: abc610e0 ("fs/epoll: avoid barrier after an epoll_wait(2) timeout")
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Tested-by: Guantao Liu <guantaol@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Guantao Liu <guantaol@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mem_cgroup_page_lruvec() in memcontrol.c and mem_cgroup_lruvec() in
memcontrol.h is very similar except for the param(page and memcg) which
also can be convert to each other.

So rewrite mem_cgroup_page_lruvec() with mem_cgroup_lruvec().

[alex.shi@linux.alibaba.com: add missed warning in mem_cgroup_lruvec]
  Link: https://lkml.kernel.org/r/94f17bb7-ec61-5b72-3555-fabeb5a4d73b@linux.alibaba.com
[lstoakes@gmail.com: warn on missing memcg on mem_cgroup_page_lruvec()]
  Link: https://lkml.kernel.org/r/20201125112202.387009-1-lstoakes@gmail.com

Link: https://lkml.kernel.org/r/20201108143731.GA74138@rlkSigned-off-by: Hui Su <sh_def@163.com>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A VCPU of a VM can allocate couple of pages which can be mmap'ed by the
user space application. At the moment this memory is not charged to the
memcg of the VMM. On a large machine running large number of VMs or
small number of VMs having large number of VCPUs, this unaccounted
memory can be very significant. So, charge this memory to the memcg of
the VMM. Please note that lifetime of these allocations corresponds to
the lifetime of the VMM.

Link: https://lkml.kernel.org/r/20201106202923.2087414-1-shakeelb@google.comSigned-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Some definitions are left unused, just clean them.

Link: https://lkml.kernel.org/r/20201108003834.12669-1-richard.weiyang@gmail.comSigned-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add VM_WARN_ON_ONCE_PAGE() macro.

Since readahead page is charged on memcg too, in theory we don't have to
check this exception now.  Before safely remove them all, add a warning
for the unexpected !memcg.

Link: https://lkml.kernel.org/r/1604283436-18880-3-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "bail out early for memcg disable".

These 2 patches are indepenedent from per memcg lru lock, and may
encounter unexpected warning, so let's move out them from per memcg
lru locking patchset.

This patch (of 2):

We could bail out early when memcg wasn't enabled.

Link: https://lkml.kernel.org/r/1604283436-18880-1-git-send-email-alex.shi@linux.alibaba.com
Link: https://lkml.kernel.org/r/1604283436-18880-2-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This test is a minimalized version of the reproducer given by syzbot
(cf. [1]).

After introducing CLOSE_RANGE_CLOEXEC syzbot reported a crash when
CLOSE_RANGE_CLOEXEC is specified in conjunction with
CLOSE_RANGE_UNSHARE. When CLOSE_RANGE_UNSHARE is specified the caller
will receive a private file descriptor table in case their file
descriptor table is currently shared.
For the case where the caller has requested all file descriptors to be
actually closed via e.g. close_range(3, ~0U, 0) the kernel knows that
the caller does not need any of the file descriptors anymore and will
optimize the close operation by only copying all files in the range from
0 to 3 and no others.

However, if the caller requested CLOSE_RANGE_CLOEXEC together with
CLOSE_RANGE_UNSHARE the caller wants to still make use of the file
descriptors so the kernel needs to copy all of them and can't optimize.

The original patch didn't account for this and thus could cause oopses
as evidenced by the syzbot report. Add tests for this regression.

We first create a huge gap in the fd table. When we now call
CLOSE_RANGE_UNSHARE with a shared fd table and and with ~0U as upper
bound the kernel will only copy up to fd1 file descriptors into the new
fd table. If the kernel is buggy and doesn't handle CLOSE_RANGE_CLOEXEC
correctly it will not have copied all file descriptors and we will oops!

This test passes on a fixed kernel and will trigger an oops on a buggy
kernel.

[1]: https://syzkaller.appspot.com/text?tag=KernelConfig&x=db720fe37a6a41d8

Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Cc: linux-fsdevel@vger.kernel.org
Link: syzbot+96cfd2b22b3213646a93@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20201218145415.801063-4-christian.brauner@ubuntu.comSigned-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Add a test to verify that CLOSE_RANGE_UNSHARE works correctly when combined
with CLOSE_RANGE_CLOEXEC for the single-threaded case.

Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20201218145415.801063-3-christian.brauner@ubuntu.comSigned-off-by: Christian Brauner <christian.brauner@ubuntu.com>

This improves the syscall number handling in the close_range()
selftests. This should handle any architecture.

Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20201218145415.801063-2-christian.brauner@ubuntu.comSigned-off-by: Christian Brauner <christian.brauner@ubuntu.com>

XFAIL was removed in commit 9847d24a ("selftests/harness: Refactor
XFAIL into SKIP") and its use in close_range_test was already replaced
by commit 1d44d0dd ("selftests: core: use SKIP instead of XFAIL in
close_range_test.c"). However, commit 23afeaef ("selftests: core:
add tests for CLOSE_RANGE_CLOEXEC") introduced usage of XFAIL in
TEST(close_range_cloexec). Use SKIP there as well.

Fixes: 23afeaef ("selftests: core: add tests for CLOSE_RANGE_CLOEXEC")
Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20201218112428.13662-1-tklauser@distanz.ch
Link: https://lore.kernel.org/r/20201218145415.801063-1-christian.brauner@ubuntu.comSigned-off-by: Christian Brauner <christian.brauner@ubuntu.com>

After introducing CLOSE_RANGE_CLOEXEC syzbot reported a crash when
CLOSE_RANGE_CLOEXEC is specified in conjunction with CLOSE_RANGE_UNSHARE.
When CLOSE_RANGE_UNSHARE is specified the caller will receive a private
file descriptor table in case their file descriptor table is currently
shared.

For the case where the caller has requested all file descriptors to be
actually closed via e.g. close_range(3, ~0U, 0) the kernel knows that
the caller does not need any of the file descriptors anymore and will
optimize the close operation by only copying all files in the range from
0 to 3 and no others.

However, if the caller requested CLOSE_RANGE_CLOEXEC together with
CLOSE_RANGE_UNSHARE the caller wants to still make use of the file
descriptors so the kernel needs to copy all of them and can't optimize.

The original patch didn't account for this and thus could cause oopses
as evidenced by the syzbot report because it assumed that all fds had
been copied. Fix this by handling the CLOSE_RANGE_CLOEXEC case.

syzbot reported
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: null-ptr-deref in atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline]
BUG: KASAN: null-ptr-deref in atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
BUG: KASAN: null-ptr-deref in filp_close+0x22/0x170 fs/open.c:1274
Read of size 8 at addr 0000000000000077 by task syz-executor511/8522

CPU: 1 PID: 8522 Comm: syz-executor511 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 __kasan_report mm/kasan/report.c:549 [inline]
 kasan_report.cold+0x5/0x37 mm/kasan/report.c:562
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline]
 atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
 filp_close+0x22/0x170 fs/open.c:1274
 close_files fs/file.c:402 [inline]
 put_files_struct fs/file.c:417 [inline]
 put_files_struct+0x1cc/0x350 fs/file.c:414
 exit_files+0x12a/0x170 fs/file.c:435
 do_exit+0xb4f/0x2a00 kernel/exit.c:818
 do_group_exit+0x125/0x310 kernel/exit.c:920
 get_signal+0x428/0x2100 kernel/signal.c:2792
 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x124/0x200 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x447039
Code: Unable to access opcode bytes at RIP 0x44700f.
RSP: 002b:00007f1b1225cdb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000001 RBX: 00000000006dbc28 RCX: 0000000000447039
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00000000006dbc2c
RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c
R13: 00007fff223b6bef R14: 00007f1b1225d9c0 R15: 00000000006dbc2c
==================================================================

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+96cfd2b22b3213646a93@syzkaller.appspotmail.com

Tested on:

commit:         10f7cddd selftests/core: add regression test for CLOSE_RAN..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git vfs
kernel config:  https://syzkaller.appspot.com/x/.config?x=5d42216b510180e3
dashboard link: https://syzkaller.appspot.com/bug?extid=96cfd2b22b3213646a93
compiler:       gcc (GCC) 10.1.0-syz 20200507

Reported-by: syzbot+96cfd2b22b3213646a93@syzkaller.appspotmail.com
Fixes: 582f1fb6 ("fs, close_range: add flag CLOSE_RANGE_CLOEXEC")
Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20201217213303.722643-1-christian.brauner@ubuntu.comSigned-off-by: Christian Brauner <christian.brauner@ubuntu.com>

commit bfda93ae ("xen: Kconfig: nest Xen guest options")
accidentally re-added X86_64 as a dependency to XEN_512GB.  It was
originally removed in commit a13f2ef1 ("x86/xen: remove 32-bit Xen
PV guest support").  Remove it again.

Fixes: bfda93ae ("xen: Kconfig: nest Xen guest options")
Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20201216140838.16085-1-jandryuk@gmail.comSigned-off-by: Juergen Gross <jgross@suse.com>

If iter->count is 0 and iocb->ki_pos is page aligned, this causes
nr_pages to be 0.

Then in generic_file_buffered_read_get_pages() find_get_pages_contig()
returns 0 - because we asked for 0 pages, so we call
generic_file_buffered_read_no_cached_page() which attempts to add a page
to the page cache, which fails with -EEXIST, and then we loop. Oops...
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Reported-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull xfs updates from Darrick Wong:
 "In this release we add the ability to set a 'needsrepair' flag
  indicating that we /know/ the filesystem requires xfs_repair, but
  other than that, it's the usual strengthening of metadata validation
  and miscellaneous cleanups.

  Summary:

   - Introduce a "needsrepair" "feature" to flag a filesystem as needing
     a pass through xfs_repair. This is key to enabling filesystem
     upgrades (in xfs_db) that require xfs_repair to make minor
     adjustments to metadata.

   - Refactor parameter checking of recovered log intent items so that
     we actually use the same validation code as them that generate the
     intent items.

   - Various fixes to online scrub not reacting correctly to directory
     entries pointing to inodes that cannot be igetted.

   - Refactor validation helpers for data and rt volume extents.

   - Refactor XFS_TRANS_DQ_DIRTY out of existence.

   - Fix a longstanding bug where mounting with "uqnoenforce" would
     start user quotas in non-enforcing mode but /proc/mounts would
     display "usrquota", implying that they are being enforced.

   - Don't flag dax+reflink inodes as corruption since that is a valid
     (but not fully functional) combination right now.

   - Clean up raid stripe validation functions.

   - Refactor the inode allocation code to be more straightforward.

   - Small prep cleanup for idmapping support.

   - Get rid of the xfs_buf_t typedef"

* tag 'xfs-5.11-merge-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (40 commits)
  xfs: remove xfs_buf_t typedef
  fs/xfs: convert comma to semicolon
  xfs: open code updating i_mode in xfs_set_acl
  xfs: remove xfs_vn_setattr_nonsize
  xfs: kill ialloced in xfs_dialloc()
  xfs: spilt xfs_dialloc() into 2 functions
  xfs: move xfs_dialloc_roll() into xfs_dialloc()
  xfs: move on-disk inode allocation out of xfs_ialloc()
  xfs: introduce xfs_dialloc_roll()
  xfs: convert noroom, okalloc in xfs_dialloc() to bool
  xfs: don't catch dax+reflink inodes as corruption in verifier
  xfs: fix the forward progress assertion in xfs_iwalk_run_callbacks
  xfs: remove unneeded return value check for *init_cursor()
  xfs: introduce xfs_validate_stripe_geometry()
  xfs: show the proper user quota options
  xfs: remove the unused XFS_B_FSB_OFFSET macro
  xfs: remove unnecessary null check in xfs_generic_create
  xfs: directly return if the delta equal to zero
  xfs: check tp->t_dqinfo value instead of the XFS_TRANS_DQ_DIRTY flag
  xfs: delete duplicated tp->t_dqinfo null check and allocation
  ...

Pull ktest updates from Steven Rostedt:
 "No new features. Just a couple of fixes that I had in my local
  repository that fixed issues with sending the result emails"

* tag 'ktest-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-ktest:
  ktest.pl: Fix the logic for truncating the size of the log file for email
  ktest.pl: If size of log is too big to email, email error message

Pull more drm updates from Daniel Vetter:
 "UAPI Changes:

   - Only enable char/agp uapi when CONFIG_DRM_LEGACY is set

  Cross-subsystem Changes:

   - vma_set_file helper to make vma->vm_file changing less brittle,
     acked by Andrew

  Core Changes:

   - dma-buf heaps improvements

   - pass full atomic modeset state to driver callbacks

   - shmem helpers: cached bo by default

   - cleanups for fbdev, fb-helpers

   - better docs for drm modes and SCALING_FITLER uapi

   - ttm: fix dma32 page pool regression

  Driver Changes:

   - multi-hop regression fixes for amdgpu, radeon, nouveau

   - lots of small amdgpu hw enabling fixes (display, pm, ...)

   - fixes for imx, mcde, meson, some panels, virtio, qxl, i915, all
     fairly minor

   - some cleanups for legacy drm/fbdev drivers"

* tag 'drm-next-2020-12-18' of git://anongit.freedesktop.org/drm/drm: (117 commits)
  drm/qxl: don't allocate a dma_address array
  drm/nouveau: fix multihop when move doesn't work.
  drm/i915/tgl: Fix REVID macros for TGL to fetch correct stepping
  drm/i915: Fix mismatch between misplaced vma check and vma insert
  drm/i915/perf: also include Gen11 in OATAILPTR workaround
  Revert "drm/i915: re-order if/else ladder for hpd_irq_setup"
  drm/amdgpu/disply: fix documentation warnings in display manager
  drm/amdgpu: print mmhub client name for dimgrey_cavefish
  drm/amdgpu: set mode1 reset as default for dimgrey_cavefish
  drm/amd/display: Add get_dig_frontend implementation for DCEx
  drm/radeon: remove h from printk format specifier
  drm/amdgpu: remove h from printk format specifier
  drm/amdgpu: Fix spelling mistake "Heterogenous" -> "Heterogeneous"
  drm/amdgpu: fix regression in vbios reservation handling on headless
  drm/amdgpu/SRIOV: Extend VF reset request wait period
  drm/amdkfd: correct amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu log.
  drm/amd/display: Adding prototype for dccg21_update_dpp_dto()
  drm/amdgpu: print what method we are using for runtime pm
  drm/amdgpu: simplify logic in atpx resume handling
  drm/amdgpu: no need to call pci_ignore_hotplug for _PR3
  ...