We hit following warning when running tests on kernel
compiled with CONFIG_DEBUG_ATOMIC_SLEEP=y:

 WARNING: CPU: 19 PID: 4472 at mm/gup.c:2381 __get_user_pages_fast+0x1a4/0x200
 CPU: 19 PID: 4472 Comm: dummy Not tainted 5.6.0-rc6+ #3
 RIP: 0010:__get_user_pages_fast+0x1a4/0x200
 ...
 Call Trace:
  perf_prepare_sample+0xff1/0x1d90
  perf_event_output_forward+0xe8/0x210
  __perf_event_overflow+0x11a/0x310
  __intel_pmu_pebs_event+0x657/0x850
  intel_pmu_drain_pebs_nhm+0x7de/0x11d0
  handle_pmi_common+0x1b2/0x650
  intel_pmu_handle_irq+0x17b/0x370
  perf_event_nmi_handler+0x40/0x60
  nmi_handle+0x192/0x590
  default_do_nmi+0x6d/0x150
  do_nmi+0x2f9/0x3c0
  nmi+0x8e/0xd7

While __get_user_pages_fast() is IRQ-safe, it calls access_ok(),
which warns on:

  WARN_ON_ONCE(!in_task() && !pagefault_disabled())

Peter suggested disabling page faults around __get_user_pages_fast(),
which gets rid of the warning in access_ok() call.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200407141427.3184722-1-jolsa@kernel.org

The uncore subsystem in Ice Lake server is similar to previous server.
There are some differences in config register encoding and pci device
IDs. The uncore PMON units in Ice Lake server include Ubox, Chabox, IIO,
IRP, M2PCIE, PCU, M2M, PCIE3 and IMC.

 - For CHA, filter 1 register has been removed. The filter 0 register can
   be used by and of CHA events to be filterd by Thread/Core-ID. To do
   so, the control register's tid_en bit must be set to 1.
 - For IIO, there are some changes on event constraints. The MSR address
   and MSR offsets among counters are also changed.
 - For IRP, the MSR address and MSR offsets among counters are changed.
 - For M2PCIE, the counters are accessed by MSR now. Add new MSR address
   and MSR offsets. Change event constraints.
 - To determine the number of CHAs, have to read CAPID6(Low) and CAPID7
   (High) now.
 - For M2M, update the PCICFG address and Device ID.
 - For UPI, update the PCICFG address, Device ID and counter address.
 - For M3UPI, update the PCICFG address, Device ID, counter address and
   event constraints.
 - For IMC, update the formular to calculate MMIO BAR address, which is
   MMIO_BASE + specific MEM_BAR offset.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/1585842411-150452-1-git-send-email-kan.liang@linux.intel.com

The void* in perf_less_group_idx() is to a member in the array which points
at a perf_event*, as such it is a perf_event**.
Reported-By: John Sperbeck <jsperbeck@google.com>
Fixes: 6eef8a71 ("perf/core: Use min_heap in visit_groups_merge()")
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200321164331.107337-1-irogers@google.com

Song reports that installing cgroup events is broken since:

  db0503e4 ("perf/core: Optimize perf_install_in_event()")

The problem being that cgroup events try to track cpuctx->cgrp even
for disabled events, which is pointless and actively harmful since the
above commit. Rework the code to have explicit enable/disable hooks
for cgroup events, such that we can limit cgroup tracking to active
events.

More specifically, since the above commit disabled events are no
longer added to their context from the 'right' CPU, and we can't
access things like the current cgroup for a remote CPU.

Cc: <stable@vger.kernel.org> # v5.5+
Fixes: db0503e4 ("perf/core: Optimize perf_install_in_event()")
Reported-by: Song Liu <songliubraving@fb.com>
Tested-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200318193337.GB20760@hirez.programming.kicks-ass.net

Pull drm fixes from Dave Airlie:
 "This is a set of fixes that have queued up, I think I might have
  another pull with some more before rc1 but I'd like to dequeue what I
  have now just in case Easter is more eggciting that expected.

  The main thing in here is a fix for a longstanding nouveau power
  management issues on certain laptops, it should help runtime
  suspend/resume for a lot of people.

  There is also a reverted patch for some drm_mm behaviour in atomic
  contexts.

  Summary:

  core:
   - revert drm_mm atomic patch
   - dt binding fixes

  fbcon:
   - null ptr error fix

  i915:
   - GVT fixes

  nouveau:
   - runpm fix
   - svm fixes

  amdgpu:
   - HDCP fixes
   - gfx10 fix
   - Misc display fixes
   - BACO fixes

  amdkfd:
   - Fix memory leak

  vboxvideo:
   - remove conflicting fbs

  vc4:
   - mode validation fix

  xen:
   - fix PTR_ERR usage"

* tag 'drm-next-2020-04-08' of git://anongit.freedesktop.org/drm/drm: (41 commits)
  drm/nouveau/kms/nv50-: wait for FIFO space on PIO channels
  drm/nouveau/nvif: protect waits against GPU falling off the bus
  drm/nouveau/nvif: access PTIMER through usermode class, if available
  drm/nouveau/gr/gp107,gp108: implement workaround for HW hanging during init
  drm/nouveau: workaround runpm fail by disabling PCI power management on certain intel bridges
  drm/nouveau/svm: remove useless SVM range check
  drm/nouveau/svm: check for SVM initialized before migrating
  drm/nouveau/svm: fix vma range check for migration
  drm/nouveau: remove checks for return value of debugfs functions
  drm/nouveau/ttm: evict other IO mappings when running out of BAR1 space
  drm/amdkfd: kfree the wrong pointer
  drm/amd/display: increase HDCP authentication delay
  drm/amd/display: Correctly cancel future watchdog and callback events
  drm/amd/display: Don't try hdcp1.4 when content_type is set to type1
  drm/amd/powerplay: move the ASIC specific nbio operation out of smu_v11_0.c
  drm/amd/powerplay: drop redundant BIF doorbell interrupt operations
  drm/amd/display: Fix dcn21 num_states
  drm/amd/display: Enable BT2020 in COLOR_ENCODING property
  drm/amd/display: LFC not working on 2.0x range monitors (v2)
  drm/amd/display: Support plane level CTM
  ...

Pull input updates from Dmitry Torokhov:
 "An update to the Goodix touchscreen driver to enable it work properly
  on various Bay Trail and Cherry Trail devices, and a few other
  assorted changes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (26 commits)
  Input: update SPDX tag for input-event-codes.h
  Input: i8042 - add Acer Aspire 5738z to nomux list
  Input: goodix - fix compilation when ACPI support is disabled
  dt-bindings: touchscreen: Convert edt-ft5x06 to json-schema
  Input: of_touchscreen - explicitly choose axis
  Input: goodix - support gt9147 touchpanel
  dt-bindings: touchscreen: goodix: support of gt9147
  Input: goodix - add support for Goodix GT917S
  Input: goodix - use string-based chip ID
  dt-bindings: input: touchscreen: add compatible string for Goodix GT917S
  Input: goodix - add support for more then one touch-key
  Input: goodix - fix spurious key release events
  Input: goodix - try to reset the controller if the i2c-test fails
  Input: goodix - restore config on resume if necessary
  Input: goodix - make goodix_send_cfg() take a raw buffer as argument
  Input: goodix - add minimum firmware size check
  Input: goodix - save a copy of the config from goodix_read_config()
  Input: goodix - move defines to above struct goodix_ts_data declaration
  Input: goodix - add support for controlling the IRQ pin through ACPI methods
  Input: goodix - add support for getting IRQ + reset GPIOs on Bay Trail devices
  ...

Pull thermal updates from Daniel Lezcano:

 - Convert tsens configuration DT binding to yaml (Rajeshwari)

 - Add interrupt support on the rcar sensor (Niklas Söderlund)

 - Add a new Spreadtrum thermal driver (Baolin Wang)

 - Add thermal binding for the fsl scu board, a new API to retrieve the
   sensor id bound to the thermal zone and i.MX system controller sensor
   (Anson Huang))

 - Remove warning log when a deferred probe is requested on Exynos
   (Marek Szyprowski)

 - Add the thermal monitoring unit support for imx8mm with its DT
   bindings (Anson Huang)

 - Rephrase the Kconfig text for clarity (Linus Walleij)

 - Use the gpio descriptor for the ti-soc-thermal (Linus Walleij)

 - Align msg structure to 4 bytes for i.MX SC, fix the Kconfig
   dependency, add the __may_be unused annotation for PM functions and
   the COMPILE_TEST option for imx8mm (Anson Huang)

 - Fix a dependency on regmap in Kconfig for qoriq (Yuantian Tang)

 - Add DT binding and support for the rcar gen3 r8a77961 and improve the
   error path on the rcar init function (Niklas Söderlund)

 - Cleanup and improvements for the tsens Qcom sensor (Amit Kucheria)

 - Improve code by removing lock and caching values in the rcar thermal
   sensor (Niklas Söderlund)

 - Cleanup in the qoriq drivers and add a call to
   imx_thermal_unregister_legacy_cooling in the removal function (Anson
   Huang)

 - Remove redundant 'maxItems' in tsens and sprd DT bindings (Rob
   Herring)

 - Change the thermal DT bindings by making the cooling-maps optional
   (Yuantian Tang)

 - Add Tiger Lake support (Sumeet Pawnikar)

 - Use scnprintf() for avoiding potential buffer overflow (Takashi Iwai)

 - Make pkg_temp_lock a raw_spinlock_t(Clark Williams)

 - Fix incorrect data types by changing them to signed on i.MX SC (Anson
   Huang)

 - Replace zero-length array with flexible-array member (Gustavo A. R.
   Silva)

 - Add support for i.MX8MP in the driver and in the DT bindings (Anson
   Huang)

 - Fix return value of the cpufreq_set_cur_state() function (Willy
   Wolff)

 - Remove abusing and scary WARN_ON in the cpufreq cooling device
   (Daniel Lezcano)

 - Fix build warning of incorrect argument type reported by sparse on
   imx8mm (Anson Huang)

 - Fix stub for the devfreq cooling device (Martin Blumenstingl)

 - Fix cpu idle cooling documentation (Sergey Vidishev)

* tag 'thermal-v5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux: (52 commits)
  Documentation: cpu-idle-cooling: Fix diagram for 33% duty cycle
  thermal: devfreq_cooling: inline all stubs for CONFIG_DEVFREQ_THERMAL=n
  thermal: imx8mm: Fix build warning of incorrect argument type
  thermal/drivers/cpufreq_cooling: Remove abusing WARN_ON
  thermal/drivers/cpufreq_cooling: Fix return of cpufreq_set_cur_state
  thermal: imx8mm: Add i.MX8MP support
  dt-bindings: thermal: imx8mm-thermal: Add support for i.MX8MP
  thermal: qcom: tsens.h: Replace zero-length array with flexible-array member
  thermal: imx_sc_thermal: Fix incorrect data type
  thermal: int340x_thermal: Use scnprintf() for avoiding potential buffer overflow
  thermal: int340x: processor_thermal: Add Tiger Lake support
  thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t
  dt-bindings: thermal: make cooling-maps property optional
  dt-bindings: thermal: qcom-tsens: Remove redundant 'maxItems'
  dt-bindings: thermal: sprd: Remove redundant 'maxItems'
  thermal: imx: Calling imx_thermal_unregister_legacy_cooling() in .remove
  thermal: qoriq: Sort includes alphabetically
  thermal: qoriq: Use devm_add_action_or_reset() to handle all cleanups
  thermal: rcar_thermal: Remove lock in rcar_thermal_get_current_temp()
  thermal: rcar_thermal: Do not store ctemp in rcar_thermal_priv
  ...

Pull mfd updates from Lee Jones:
 "New Drivers:
   - Add support for IQS620A/621/622/624/625 Azoteq IQS62X Sensors

  New Device Support:
   - Add support for ADC, IRQ, Regulator, RTC and WDT to Ricoh RN5T618 PMIC
   - Add support for Comet Lake to Intel LPSS

  New Functionality:
   - Add support for Charger Detection to Spreadtrum SC27xx PMICs
   - Add support for Interrupt Polarity to Dialog Semi DA9062/61 PMIC
   - Add ACPI enumeration support to Diolan DLN2 USB Adaptor

  Fix-ups:
   - Device Tree; iqs62x, rn5t618, cros_ec_dev, stm32-lptimer, rohm,bd71837, rohm,bd71847
   - I2C registration; rn5t618
   - Kconfig; MFD_CPCAP, AB8500_CORE, MFD_WM8994, MFD_WM97xx, MFD_STPMIC1
   - Use flexible-array members; omap-usb-tll, qcom-pm8xxx
   - Remove unnecessary casts; omap-usb-host, omap-usb-tll
   - Power (suspend/resume/poweroff) enhancements; rk808
   - Improve error/sanity checking; dln2
   - Use snprintf(); aat2870-core

  Bug Fixes:
   - Fix PCI IDs in intel-lpss-pci"

* tag 'mfd-next-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd: (33 commits)
  mfd: intel-lpss: Fix Intel Elkhart Lake LPSS I2C input clock
  mfd: aat2870: Use scnprintf() for avoiding potential buffer overflow
  mfd: dln2: Allow to be enumerated via ACPI
  mfd: da9062: Add support for interrupt polarity defined in device tree
  dt-bindings: bd718x7: Yamlify and add BD71850
  mfd: dln2: Fix sanity checking for endpoints
  mfd: intel-lpss: Add Intel Comet Lake PCH-V PCI IDs
  mfd: sc27xx: Add USB charger type detection support
  dt-bindings: mfd: Document STM32 low power timer bindings
  mfd: rk808: Convert RK805 to shutdown/suspend hooks
  mfd: rk808: Reduce shutdown duplication
  mfd: rk808: Stop using syscore ops
  mfd: rk808: Ensure suspend/resume hooks always work
  mfd: rk808: Always use poweroff when requested
  mfd: omap: Remove useless cast for driver.name
  mfd: Kconfig: Fix some misspelling of the word functionality
  mfd: pm8xxx: Replace zero-length array with flexible-array member
  mfd: omap-usb-tll: Replace zero-length array with flexible-array member
  mfd: cpcap: Fix compile if MFD_CORE is not selected
  mfd: cros_ec: Check DT node for usbpd-notify add
  ...

Pull backlight updates from Lee Jones:
 "Switch pwm_bl and corgi_lcd drivers to use GPIO descriptors"

* tag 'backlight-next-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  backlight: corgi: Convert to use GPIO descriptors
  backlight: pwm_bl: Switch to full GPIO descriptor

Pull LED updates from Pavel Machek:
 "One new driver, some driver changes, and some late minute cleanups --
  but those are just whitespace so should be okay.

  There are some major changes being prepared (multicolor, triggers) so
  the next release likely will be more interesting"

* tag 'leds-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds:
  leds: core: Fix warning message when init_data
  leds: make functions easier to understand
  leds: sort Makefile entries
  leds: old enums are not really applicable to new code
  leds: ip30: label power LED as such
  leds: lm3532: make bitfield 'enabled' unsigned
  leds: leds-pwm: Replace zero-length array with flexible-array member
  leds: leds-is31fl32xx: Replace zero-length array with flexible-array member
  leds: pwm: remove useless pwm_period_ns
  leds: pwm: remove header
  leds: pwm: convert to atomic PWM API
  leds: pwm: simplify if condition
  leds: add SGI IP30 led support
  leds: lm3697: fix spelling mistake "To" -> "Too"
  leds: leds-bd2802: remove set but not used variable 'pdata'
  leds: ns2: Convert to GPIO descriptors
  leds: ns2: Absorb platform data

It's definitely incorrect to mark the lock as taken even if
down_read_killable() failed.

This wass overlooked when we switched from down_read() to
down_read_killable() because down_read() won't fail while
down_read_killable() could.

Fixes: 71335f37 ("mm/gup: allow to react to fatal signals")
Reported-by: syzbot+a8c70b7f3579fc0587dc@syzkaller.appspotmail.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lookup_node() uses gup to pin the page and get node information.  It
checks against ret>=0 assuming the page will be filled in.  However it's
also possible that gup will return zero, for example, when the thread is
quickly killed with a fatal signal.  Teach lookup_node() to gracefully
return an error -EFAULT if it happens.

Meanwhile, initialize "page" to NULL to avoid potential risk of
exploiting the pointer.

Fixes: 4426e945 ("mm/gup: allow VM_FAULT_RETRY for multiple times")
Reported-by: syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

amd-drm-next-5.7-2020-04-01:

amdgpu:
- HDCP fixes
- gfx10 fix
- Misc display fixes
- BACO fixes

amdkfd:
- Fix memory leak
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Alex Deucher <alexdeucher@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200401194619.4217-1-alexander.deucher@amd.com

A couple of misc fixes/workarounds for some issues that are causing a
lot of pain for people.

Of most interest are the PCI power management and GR init WARs, which
effect a rather significant number of laptop systems that are in use
today.
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Ben Skeggs <skeggsb@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ <CACAvsv5Ef5YKS9EPBH3YUubzvVr++_rzjgSqV_B5nC0L2kB6-Q@mail.gmail.com

Merge tag 'drm-misc-next-fixes-2020-04-04' of git://anongit.freedesktop.org/drm/drm-misc into drm-next

A bunch of fixes to avoid null pointer dereference in fbcon, fix a return
in xen, some DT bindings fixes, a vc4 issue with 1920x1200 mode validation,
and a conflicting framebuffer in vboxvideo.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20200404090057.a3m7uw6tavwtcyon@gilmour.lan

Merge tag 'drm-intel-next-fixes-2020-04-02' of git://anongit.freedesktop.org/drm/drm-intel into drm-next

Only gvt fixes on this round:

- Fix non-privilege access warning (Tina)
- Fix display port type (Tina)
- BDW cmd parser missed SWTESS_BASE_ADDRESS (Yan)
- Bypass length check of LRI (Yan)
- Fix one klocwork warning (Tina)
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200402213026.GA1141017@intel.com

Merge more updates from Andrew Morton:

 - a lot more of MM, quite a bit more yet to come: (memcg, pagemap,
   vmalloc, pagealloc, migration, thp, ksm, madvise, virtio,
   userfaultfd, memory-hotplug, shmem, rmap, zswap, zsmalloc, cleanups)

 - various other subsystems (procfs, misc, MAINTAINERS, bitops, lib,
   checkpatch, epoll, binfmt, kallsyms, reiserfs, kmod, gcov, kconfig,
   ubsan, fault-injection, ipc)

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (158 commits)
  ipc/shm.c: make compat_ksys_shmctl() static
  ipc/mqueue.c: fix a brace coding style issue
  lib/Kconfig.debug: fix a typo "capabilitiy" -> "capability"
  ubsan: include bug type in report header
  kasan: unset panic_on_warn before calling panic()
  ubsan: check panic_on_warn
  drivers/misc/lkdtm/bugs.c: add arithmetic overflow and array bounds checks
  ubsan: split "bounds" checker from other options
  ubsan: add trap instrumentation option
  init/Kconfig: clean up ANON_INODES and old IO schedulers options
  kernel/gcov/fs.c: replace zero-length array with flexible-array member
  gcov: gcc_3_4: replace zero-length array with flexible-array member
  gcov: gcc_4_7: replace zero-length array with flexible-array member
  kernel/kmod.c: fix a typo "assuems" -> "assumes"
  reiserfs: clean up several indentation issues
  kallsyms: unexport kallsyms_lookup_name() and kallsyms_on_each_symbol()
  samples/hw_breakpoint: drop use of kallsyms_lookup_name()
  samples/hw_breakpoint: drop HW_BREAKPOINT_R when reporting writes
  fs/binfmt_elf.c: don't free interpreter's ELF pheaders on common path
  fs/binfmt_elf.c: allocate less for static executable
  ...

Pull NFS client updates from Trond Myklebust:
 "Highlights include:

  Stable fixes:
   - Fix a page leak in nfs_destroy_unlinked_subrequests()

   - Fix use-after-free issues in nfs_pageio_add_request()

   - Fix new mount code constant_table array definitions

   - finish_automount() requires us to hold 2 refs to the mount record

  Features:
   - Improve the accuracy of telldir/seekdir by using 64-bit cookies
     when possible.

   - Allow one RDMA active connection and several zombie connections to
     prevent blocking if the remote server is unresponsive.

   - Limit the size of the NFS access cache by default

   - Reduce the number of references to credentials that are taken by
     NFS

   - pNFS files and flexfiles drivers now support per-layout segment
     COMMIT lists.

   - Enable partial-file layout segments in the pNFS/flexfiles driver.

   - Add support for CB_RECALL_ANY to the pNFS flexfiles layout type

   - pNFS/flexfiles Report NFS4ERR_DELAY and NFS4ERR_GRACE errors from
     the DS using the layouterror mechanism.

  Bugfixes and cleanups:
   - SUNRPC: Fix krb5p regressions

   - Don't specify NFS version in "UDP not supported" error

   - nfsroot: set tcp as the default transport protocol

   - pnfs: Return valid stateids in nfs_layout_find_inode_by_stateid()

   - alloc_nfs_open_context() must use the file cred when available

   - Fix locking when dereferencing the delegation cred

   - Fix memory leaks in O_DIRECT when nfs_get_lock_context() fails

   - Various clean ups of the NFS O_DIRECT commit code

   - Clean up RDMA connect/disconnect

   - Replace zero-length arrays with C99-style flexible arrays"

* tag 'nfs-for-5.7-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (86 commits)
  NFS: Clean up process of marking inode stale.
  SUNRPC: Don't start a timer on an already queued rpc task
  NFS/pnfs: Reference the layout cred in pnfs_prepare_layoutreturn()
  NFS/pnfs: Fix dereference of layout cred in pnfs_layoutcommit_inode()
  NFS: Beware when dereferencing the delegation cred
  NFS: Add a module parameter to set nfs_mountpoint_expiry_timeout
  NFS: finish_automount() requires us to hold 2 refs to the mount record
  NFS: Fix a few constant_table array definitions
  NFS: Try to join page groups before an O_DIRECT retransmission
  NFS: Refactor nfs_lock_and_join_requests()
  NFS: Reverse the submission order of requests in __nfs_pageio_add_request()
  NFS: Clean up nfs_lock_and_join_requests()
  NFS: Remove the redundant function nfs_pgio_has_mirroring()
  NFS: Fix memory leaks in nfs_pageio_stop_mirroring()
  NFS: Fix a request reference leak in nfs_direct_write_clear_reqs()
  NFS: Fix use-after-free issues in nfs_pageio_add_request()
  NFS: Fix races nfs_page_group_destroy() vs nfs_destroy_unlinked_subrequests()
  NFS: Fix a page leak in nfs_destroy_unlinked_subrequests()
  NFS: Remove unused FLUSH_SYNC support in nfs_initiate_pgio()
  pNFS/flexfiles: Specify the layout segment range in LAYOUTGET
  ...

Pull f2fs updates from Jaegeuk Kim:
 "In this round, we've mainly focused on fixing bugs and addressing
  issues in recently introduced compression support.

  Enhancement:
   - add zstd support, and set LZ4 by default
   - add ioctl() to show # of compressed blocks
   - show mount time in debugfs
   - replace rwsem with spinlock
   - avoid lock contention in DIO reads

  Some major bug fixes wrt compression:
   - compressed block count
   - memory access and leak
   - remove obsolete fields
   - flag controls

  Other bug fixes and clean ups:
   - fix overflow when handling .flags in inode_info
   - fix SPO issue during resize FS flow
   - fix compression with fsverity enabled
   - potential deadlock when writing compressed pages
   - show missing mount options"

* tag 'f2fs-for-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (66 commits)
  f2fs: keep inline_data when compression conversion
  f2fs: fix to disable compression on directory
  f2fs: add missing CONFIG_F2FS_FS_COMPRESSION
  f2fs: switch discard_policy.timeout to bool type
  f2fs: fix to verify tpage before releasing in f2fs_free_dic()
  f2fs: show compression in statx
  f2fs: clean up dic->tpages assignment
  f2fs: compress: support zstd compress algorithm
  f2fs: compress: add .{init,destroy}_decompress_ctx callback
  f2fs: compress: fix to call missing destroy_compress_ctx()
  f2fs: change default compression algorithm
  f2fs: clean up {cic,dic}.ref handling
  f2fs: fix to use f2fs_readpage_limit() in f2fs_read_multi_pages()
  f2fs: xattr.h: Make stub helpers inline
  f2fs: fix to avoid double unlock
  f2fs: fix potential .flags overflow on 32bit architecture
  f2fs: fix NULL pointer dereference in f2fs_verity_work()
  f2fs: fix to clear PG_error if fsverity failed
  f2fs: don't call fscrypt_get_encryption_info() explicitly in f2fs_tmpfile()
  f2fs: don't trigger data flush in foreground operation
  ...

Pull UBI and UBIFS updates from Richard Weinberger:

 - Fix for memory leaks around UBIFS orphan handling

 - Fix for memory leaks around UBI fastmap

 - Remove zero-length array from ubi-media.h

 - Fix for TNC lookup in UBIFS orphan code

* tag 'for-linus-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs:
  ubi: ubi-media.h: Replace zero-length array with flexible-array member
  ubifs: Fix out-of-bounds memory access caused by abnormal value of node_len
  ubi: fastmap: Only produce the initial anchor PEB when fastmap is used
  ubi: fastmap: Free unused fastmap anchor peb during detach
  ubifs: ubifs_add_orphan: Fix a memory leak bug
  ubifs: ubifs_jnl_write_inode: Fix a memory leak bug
  ubifs: Fix ubifs_tnc_lookup() usage in do_kill_orphans()

Pull UML updates from Richard Weinberger:

 - New mode for time travel, external via virtio

 - Fixes for ubd to make sure no requests can get lost

 - Fixes for vector networking

 - Allow CONFIG_STATIC_LINK only when possible

 - Minor cleanups and fixes

* tag 'for-linus-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: Remove some unnecessary NULL checks in vector_user.c
  um: vector: Avoid NULL ptr deference if transport is unset
  um: Make CONFIG_STATIC_LINK actually static
  um: Implement cpu_relax() as ndelay(1) for time-travel
  um: Implement ndelay/udelay in time-travel mode
  um: Implement time-travel=ext
  um: virtio: Implement VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS
  um: time-travel: Rewrite as an event scheduler
  um: Move timer-internal.h to non-shared
  hostfs: Use kasprintf() instead of fixed buffer formatting
  um: falloc.h needs to be directly included for older libc
  um: ubd: Retry buffer read on any kind of error
  um: ubd: Prevent buffer overrun on command completion
  um: Fix overlapping ELF segments when statically linked
  um: Delete never executed timer
  um: Don't overwrite ethtool driver version
  um: Fix len of file in create_pid_file
  um: Don't use console_drivers directly
  um: Cleanup CONFIG_IOSCHED_CFQ

Pull OpenRISC updates from Stafford Horne:
 "A few cleanups all over the place, things of note:

   - Enable the clone3 syscall

   - Remove CONFIG_CROSS_COMPILE from Krzysztof Kozlowski

   - Update to use mmgrab from Julia Lawall"

* tag 'for-linus' of git://github.com/openrisc/linux:
  openrisc: Remove obsolete show_trace_task function
  openrisc: Cleanup copy_thread_tls docs and comments
  openrisc: Enable the clone3 syscall
  openrisc: Convert copy_thread to copy_thread_tls
  openrisc: use mmgrab
  openrisc: configs: Cleanup CONFIG_CROSS_COMPILE

Pull parisc updates from Helge Deller:
 "Some cleanups in arch_rw locking functions, improved interrupt
  handling in arch spinlocks, coversions to request_irq() and syscall
  table generation cleanups"

* 'parisc-5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: remove nargs from __SYSCALL
  parisc: Refactor alternative code to accept multiple conditions
  parisc: Rework arch_rw locking functions
  parisc: Improve interrupt handling in arch_spin_lock_flags()
  parisc: Replace setup_irq() by request_irq()

Pull sparc update from David Miller:
 "A per-device DMA ops conversion for sparc32 by Chrstioph Hellwig"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  sparc32: use per-device dma_ops

Pull IDE update from David Miller:
 "As usual, very quiet in this subsystem.

  Just a list_for_each_entry_safe() conversion"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/ide:
  drivers/ide: Fix build regression.
  drivers/ide: convert to list_for_each_entry_safe()

Pull networking fixes from David Miller:

 1) Slave bond and team devices should not be assigned ipv6 link local
    addresses, from Jarod Wilson.

 2) Fix clock sink config on some at803x PHY devices, from Oleksij
    Rempel.

 3) Uninitialized stack space transmitted in slcan frames, fix from
    Richard Palethorpe.

 4) Guard HW VLAN ops properly in stmmac driver, from Jose Abreu.

 5) "=" --> "|=" fix in aquantia driver, from Colin Ian King.

 6) Fix TCP fallback in mptcp, from Florian Westphal. (accessing a plain
    tcp_sk as if it were an mptcp socket).

 7) Fix cavium driver in some configurations wrt. PTP, from Yue Haibing.

 8) Make ipv6 and ipv4 consistent in the lower bound allowed for
    neighbour entry retrans_time, from Hangbin Liu.

 9) Don't use private workqueue in pegasus usb driver, from Petko
    Manolov.

10) Fix integer overflow in mlxsw, from Colin Ian King.

11) Missing refcnt init in cls_tcindex, from Cong Wang.

12) One too many loop iterations when processing cmpri entries in ipv6
    rpl code, from Alexander Aring.

13) Disable SG and TSO by default in r8169, from Heiner Kallweit.

14) NULL deref in macsec, from Davide Caratti.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (42 commits)
  macsec: fix NULL dereference in macsec_upd_offload()
  skbuff.h: Improve the checksum related comments
  net: dsa: bcm_sf2: Ensure correct sub-node is parsed
  qed: remove redundant assignment to variable 'rc'
  wimax: remove some redundant assignments to variable result
  mlxsw: spectrum_flower: Do not stop at FLOW_ACTION_VLAN_MANGLE
  mlxsw: spectrum_flower: Do not stop at FLOW_ACTION_PRIORITY
  r8169: change back SG and TSO to be disabled by default
  net: dsa: bcm_sf2: Do not register slave MDIO bus with OF
  ipv6: rpl: fix loop iteration
  tun: Don't put_page() for all negative return values from XDP program
  net: dsa: mt7530: fix null pointer dereferencing in port5 setup
  mptcp: add some missing pr_fmt defines
  net: phy: micrel: kszphy_resume(): add delay after genphy_resume() before accessing PHY registers
  net_sched: fix a missing refcnt in tcindex_init()
  net: stmmac: dwmac1000: fix out-of-bounds mac address reg setting
  mlxsw: spectrum_trap: fix unintention integer overflow on left shift
  pegasus: Remove pegasus' own workqueue
  neigh: support smaller retrans_time settting
  net: openvswitch: use hlist_for_each_entry_rcu instead of hlist_for_each_entry
  ...

Pull pcmcia updates from Dominik Brodowski:
 "A few PCMCIA odd fixes: removing a few spaces and useless casts,
  replacing snprintf() with scnprintf(), and replacing zero-length
  arrays with a flexible-array member"

* 'pcmcia-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux:
  pcmcia: remove some unused space characters
  pcmcia: soc_common.h: Replace zero-length array with flexible-array member
  pcmcia: cs_internal.h: Replace zero-length array with flexible-array member
  pcmcia: Use scnprintf() for avoiding potential buffer overflow
  pcmcia: omap: remove useless cast for driver.name

Fix the following sparse warning:

ipc/shm.c:1335:6: warning: symbol 'compat_ksys_shmctl' was not declared.
Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200403063933.24785-1-yanaijie@huawei.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: somala swaraj <somalaswaraj@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200301135530.18340-1-somalaswaraj@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

s/capabilitiy/capability
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1585818594-27373-1-git-send-email-hqjagain@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When syzbot tries to figure out how to deduplicate bug reports, it prefers
seeing a hint about a specific bug type (we can do better than just
"UBSAN").  This lifts the handler reason into the UBSAN report line that
includes the file path that tripped a check.  Unfortunately, UBSAN does
not provide function names.
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Elena Petrova <lenaptr@google.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Link: http://lkml.kernel.org/r/20200227193516.32566-7-keescook@chromium.org
Link: https://lore.kernel.org/lkml/CACT4Y+bsLJ-wFx_TaXqax3JByUOWB3uk787LsyMVcfW6JzzGvg@mail.gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

As done in the full WARN() handler, panic_on_warn needs to be cleared
before calling panic() to avoid recursive panics.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Elena Petrova <lenaptr@google.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Link: http://lkml.kernel.org/r/20200227193516.32566-6-keescook@chromium.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Syzkaller expects kernel warnings to panic when the panic_on_warn sysctl
is set.  More work is needed here to have UBSan reuse the WARN
infrastructure, but for now, just check the flag manually.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Elena Petrova <lenaptr@google.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Link: https://lore.kernel.org/lkml/CACT4Y+bsLJ-wFx_TaXqax3JByUOWB3uk787LsyMVcfW6JzzGvg@mail.gmail.com
Link: http://lkml.kernel.org/r/20200227193516.32566-5-keescook@chromium.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Adds LKDTM tests for arithmetic overflow (both signed and unsigned), as
well as array bounds checking.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Elena Petrova <lenaptr@google.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Link: http://lkml.kernel.org/r/20200227193516.32566-4-keescook@chromium.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In order to do kernel builds with the bounds checker individually
available, introduce CONFIG_UBSAN_BOUNDS, with the remaining options under
CONFIG_UBSAN_MISC.

For example, using this, we can start to expand the coverage syzkaller is
providing.  Right now, all of UBSan is disabled for syzbot builds because
taken as a whole, it is too noisy.  This will let us focus on one feature
at a time.

For the bounds checker specifically, this provides a mechanism to
eliminate an entire class of array overflows with close to zero
performance overhead (I cannot measure a difference).  In my (mostly)
defconfig, enabling bounds checking adds ~4200 checks to the kernel.
Performance changes are in the noise, likely due to the branch predictors
optimizing for the non-fail path.

Some notes on the bounds checker:

- it does not instrument {mem,str}*()-family functions, it only
  instruments direct indexed accesses (e.g. "foo[i]"). Dealing with
  the {mem,str}*()-family functions is a work-in-progress around
  CONFIG_FORTIFY_SOURCE[1].

- it ignores flexible array members, including the very old single
  byte (e.g. "int foo[1];") declarations. (Note that GCC's
  implementation appears to ignore _all_ trailing arrays, but Clang only
  ignores empty, 0, and 1 byte arrays[2].)

[1] https://github.com/KSPP/linux/issues/6
[2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92589Suggested-by: Elena Petrova <lenaptr@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Link: http://lkml.kernel.org/r/20200227193516.32566-3-keescook@chromium.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "ubsan: Split out bounds checker", v5.

This splits out the bounds checker so it can be individually used.  This
is enabled in Android and hopefully for syzbot.  Includes LKDTM tests for
behavioral corner-cases (beyond just the bounds checker), and adjusts
ubsan and kasan slightly for correct panic handling.

This patch (of 6):

The Undefined Behavior Sanitizer can operate in two modes: warning
reporting mode via lib/ubsan.c handler calls, or trap mode, which uses
__builtin_trap() as the handler.  Using lib/ubsan.c means the kernel image
is about 5% larger (due to all the debugging text and reporting structures
to capture details about the warning conditions).  Using the trap mode,
the image size changes are much smaller, though at the loss of the
"warning only" mode.

In order to give greater flexibility to system builders that want minimal
changes to image size and are prepared to deal with kernel code being
aborted and potentially destabilizing the system, this introduces
CONFIG_UBSAN_TRAP.  The resulting image sizes comparison:

   text    data     bss       dec       hex     filename
19533663   6183037  18554956  44271656  2a38828 vmlinux.stock
19991849   7618513  18874448  46484810  2c54d4a vmlinux.ubsan
19712181   6284181  18366540  44362902  2a4ec96 vmlinux.ubsan-trap

CONFIG_UBSAN=y:      image +4.8% (text +2.3%, data +18.9%)
CONFIG_UBSAN_TRAP=y: image +0.2% (text +0.9%, data +1.6%)

Additionally adjusts the CONFIG_UBSAN Kconfig help for clarity and removes
the mention of non-existing boot param "ubsan_handle".
Suggested-by: Elena Petrova <lenaptr@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Link: http://lkml.kernel.org/r/20200227193516.32566-2-keescook@chromium.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

CONFIG_ANON_INODES is gone since commit 5dd50aae ("Make anon_inodes
unconditional").

CONFIG_CFQ_GROUP_IOSCHED was replaced with CONFIG_BFQ_GROUP_IOSCHED in
commit f382fb0b ("block: remove legacy IO schedulers").
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/20200130192419.3026-1-krzk@kernel.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied.  As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Link: http://lkml.kernel.org/r/20200302224851.GA26467@embeddedorSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied.  As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Link: http://lkml.kernel.org/r/20200302224501.GA14175@embeddedorSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied.  As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Link: http://lkml.kernel.org/r/20200213152241.GA877@embeddedorSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>