Add MAINTAINERS entry for Qualcomm IPCC driver and its binding.
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

Add support for the Inter-Processor Communication Controller (IPCC)
block from Qualcomm that coordinates the interrupts (inbound & outbound)
for Multiprocessor (MPROC), COMPUTE-Level0 (COMPUTE-L0) & COMPUTE-Level1
(COMPUTE-L1) protocols for the Application Processor Subsystem (APSS).

This driver is modeled as an irqchip+mailbox driver. The irqchip part
helps in receiving the interrupts from the IPCC clients such as modems,
DSPs, PCI-E etc... and forwards them to respective entities in APSS.

On the other hand, the mailbox part is used to send interrupts to the IPCC
clients from the entities of APSS.
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>
Signed-off-by: Venkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
[mani: moved to mailbox, added static mbox channels and cleanups]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

Add devicetree YAML binding for Qualcomm Inter-Processor Communication
Controller (IPCC) block.
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

In case of error, the function devm_ioremap() returns NULL pointer not
ERR_PTR(). So we should check whether the return value of devm_ioremap()
is NULL instead of IS_ERR.

Fixes: 4981b82b ("mailbox: ZynqMP IPI mailbox controller")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

The i.MX8 SCU message header size is the number of "u32" elements,
not "u8", so fix the check.
Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1461658 ("Memory - corruptions")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Leonard Crestez <leonard.crestez@nxp.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

The Spreadtrum mailbox controller supports 8 channels to communicate
with MCUs, and it contains 2 different parts: inbox and outbox, which
are used to send and receive messages by IRQ mode.
Signed-off-by: Baolin Wang <baolin.wang@unisoc.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

Add the Spreadtrum mailbox documentation.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Baolin Wang <baolin.wang@unisoc.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

The function platform_get_irq can log an error already.
Thus omit a redundant message for the exception handling in the
calling function.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

devm_mbox_controller_register() may fail, and in the case of failure the
priv->clk clock that was previously enabled, should be disabled.

Fixes: 2bb70056 ("mailbox: Add support for i.MX messaging unit")
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
[Jassi: fixed merge/am conflict]
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

This called from mbox_request_channel().  The caller is  expecting error
pointers and not NULL so this "return NULL;" will lead to an Oops.

Fixes: 0a67003b ("mailbox: imx: add SCU MU support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

Some power hungry sub-systems like VPU has its own MUs which also
use mailbox driver, current mailbox driver uses platform driver
model and MU's power will be ON after driver probed and left ON
there, it may cause the whole sub-system can NOT enter lower power
mode, take VPU driver for example, it has runtime PM support, but
due to its MU always ON, the VPU sub-system will be always ON and
consume many power during kernel idle.

To save power in kernel idle, mailbox driver needs to support
runtime PM in order to power off MU when it is unused. However,
the runtime suspend/resume can ONLY be implemented in mailbox's
.shutdown/.startup callback, so its consumer needs to call
mbox_request_channel()/mbox_free_channel() in consumer driver's
runtime PM callback, then the MU's power will be ON/OFF along with
consumer's runtime PM status.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

Fix the following sparse warning:

drivers/mailbox/pcc.c:571:24: warning: symbol 'pcc_mbox_driver' 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: Jassi Brar <jaswinder.singh@linaro.org>

Pull powerpc fixes from Michael Ellerman:

 - a fix for the recent change to how we restore non-volatile GPRs,
   which broke our emulation of reading from the DSCR (Data Stream
   Control Register).

 - a fix for the recent rewrite of interrupt/syscall exit in C, we need
   to exclude KCOV from that code, otherwise it can lead to
   unrecoverable faults.

Thanks to Daniel Axtens.

* tag 'powerpc-5.7-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64s: Disable sanitisers for C syscall/interrupt entry/exit code
  powerpc/64s: Fix restore of NV GPRs after facility unavailable exception

Pull GPIO fixes from Linus Walleij:
 "Here are some (very) late fixes for GPIO, none of them very serious
  except the one tagged for stable for enabling IRQ on open drain lines:

   - Fix probing of mvebu chips without PWM

   - Fix error path on ida_get_simple() on the exar driver

   - Notify userspace properly about line status changes when flags are
     changed on lines.

   - Fix a sleeping while holding spinlock in the mellanox driver.

   - Fix return value of the PXA and Kona probe calls.

   - Fix IRQ locking of open drain lines, it is fine to have IRQs on
     open drain lines flagged for output"

* tag 'gpio-v5.7-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: fix locking open drain IRQ lines
  gpio: bcm-kona: Fix return value of bcm_kona_gpio_probe()
  gpio: pxa: Fix return value of pxa_gpio_probe()
  gpio: mlxbf2: Fix sleeping while holding spinlock
  gpiolib: notify user-space about line status changes after flags are set
  gpio: exar: Fix bad handling for ida_simple_get error path
  gpio: mvebu: Fix probing for chips without PWM

Pull ARM SoC fixes from Arnd Bergmann:
 "This time there is one fix for the error path in the mediatek cmdq
  driver (used by their video driver) and a couple of devicetree fixes,
  mostly for 32-bit ARM, and fairly harmless:

   - On OMAP2 there were a few regressions in the ethernet drivers, one
     of them leading to an external abort trap

   - One Raspberry Pi version had a misconfigured LED

   - Interrupts on Broadcom NSP were slightly misconfigured

   - One i.MX6q board had issues with graphics mode setting

   - On mmp3 there are some minor fixes that were submitted for v5.8
     with a cc:stable tag, so I ended up picking them up here as well

   - The Mediatek Video Codec needs to run at a higher frequency than
     configured originally"

* tag 'armsoc-fixes-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
  ARM: dts: mmp3: Drop usb-nop-xceiv from HSIC phy
  ARM: dts: mmp3-dell-ariel: Fix the SPI devices
  ARM: dts: mmp3: Use the MMP3 compatible string for /clocks
  ARM: dts: bcm: HR2: Fix PPI interrupt types
  ARM: dts: bcm2835-rpi-zero-w: Fix led polarity
  ARM: dts/imx6q-bx50v3: Set display interface clock parents
  soc: mediatek: cmdq: return send msg error code
  arm64: dts: mt8173: fix vcodec-enc clock
  ARM: dts: Fix wrong mdio clock for dm814x
  ARM: dts: am437x: fix networking on boards with ksz9031 phy
  ARM: dts: am57xx: fix networking on boards with ksz9031 phy

Pull ceph fixes from Ilya Dryomov:
 "Cache tiering and cap handling fixups, both marked for stable"

* tag 'ceph-for-5.7-rc8' of git://github.com/ceph/ceph-client:
  ceph: flush release queue when handling caps for unknown inode
  libceph: ignore pool overlay and cache logic on redirects

Pull gfs2 fix from Andreas Gruenbacher:
 "Fix the previous, flawed gfs2_find_jhead commit"

* tag 'gfs2-v5.7-rc7.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Even more gfs2_find_jhead fixes

Pull arm64 fix from Catalin Marinas:
 "Ensure __cpu_up() returns an error if cpu_online() is false after
  waiting for completion on cpu_running"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/kernel: Fix return value when cpu_online() fails in __cpu_up()

Pull parisc fix from Helge Deller:
 "Fix a kernel panic at boot time for some HP-PARISC machines"

* 'parisc-5.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Fix kernel panic in mem_init()

Pull iommu fixes from Joerg Roedel:

 - Two build fixes for issues introduced during the merge window

 - A fix for a reference count leak in an error path of
   iommu_group_alloc()

* tag 'iommu-fixes-v5.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu: Fix reference count leak in iommu_group_alloc.
  x86: Hide the archdata.iommu field behind generic IOMMU_API
  ia64: Hide the archdata.iommu field behind generic IOMMU_API

Pull block fixes from Jens Axboe:
 "Two small fixes:

   - Revert a block change that mixed up the return values for non-mq
     devices

   - NVMe poll race fix"

* tag 'block-5.7-2020-05-29' of git://git.kernel.dk/linux-block:
  Revert "block: end bio with BLK_STS_AGAIN in case of non-mq devs and REQ_NOWAIT"
  nvme-pci: avoid race between nvme_reap_pending_cqes() and nvme_poll()

Pull rdma fixes from Jason Gunthorpe:
 "Nothing profound here, just a last set of long standing bug fixes:

   - Incorrect error unwind in qib and pvrdma

   - User triggerable NULL pointer crash in mlx5 with ODP prefetch

   - syzkaller RCU race in uverbs

   - Rare double free crash in ipoib"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
  IB/ipoib: Fix double free of skb in case of multicast traffic in CM mode
  RDMA/core: Fix double destruction of uobject
  RDMA/pvrdma: Fix missing pci disable in pvrdma_pci_probe()
  RDMA/mlx5: Fix NULL pointer dereference in destroy_prefetch_work
  IB/qib: Call kobject_put() when kobject_init_and_add() fails

Pull MMC fixes from Ulf Hansson:
 "MMC core:
   - Fix use-after-free issue for rpmb partition

  MMC host:
   - Fix quirk for broken CQE support"

* tag 'mmc-v5.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: block: Fix use-after-free issue for rpmb
  mmc: sdhci: Fix SDHCI_QUIRK_BROKEN_CQE

Pull sound fixes from Takashi Iwai:
 "Only a few last-minute small fixes: the change in ALSA core hwdep is
  about the undefined behavior of bit shift, which is almost harmless
  but still worth to pick up quickly.

  The rest are all device-specific fixes for HD-audio and USB-audio, and
  safe to apply at the late stage"

* tag 'sound-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda/realtek - Add new codec supported for ALC287
  ALSA: usb-audio: Quirks for Gigabyte TRX40 Aorus Master onboard audio
  ALSA: usb-audio: mixer: volume quirk for ESS Technology Asus USB DAC
  ALSA: hda/realtek - Add a model for Thinkpad T570 without DAC workaround
  ALSA: hwdep: fix a left shifting 1 by 31 UB bug

Pull clk fixes from Stephen Boyd:
 "Two fixes for the new SM8150 and SM8250 Qualcomm clk drivers to fix a
  randconfig build error and an incorrect parent mapping"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: qcom: gcc: Fix parent for gpll0_out_even
  clk: qcom: sm8250 gcc depends on QCOM_GDSC

Pull drm fixes from Dave Airlie:
 "A couple of amdgpu fixes and minor ingenic fixes:

  amdgpu:
   - display atomic test fix
   - Fix soft hang in display vupdate code

  ingenic:
   - fix pointer cast
   - fix crtc atomic check callback"

* tag 'drm-fixes-2020-05-29-1' of git://anongit.freedesktop.org/drm/drm:
  drm/amd/display: Fix potential integer wraparound resulting in a hang
  drm/amd/display: drop cursor position check in atomic test
  gpu/drm: Ingenic: Fix opaque pointer casted to wrong type
  gpu/drm: ingenic: Fix bogus crtc_atomic_check callback

Fix several issues in the previous gfs2_find_jhead fix:
* When updating @blocks_submitted, @block refers to the first block block not
  submitted yet, not the last block submitted, so fix an off-by-one error.
* We want to ensure that @blocks_submitted is far enough ahead of @blocks_read
  to guarantee that there is in-flight I/O.  Otherwise, we'll eventually end up
  waiting for pages that haven't been submitted, yet.
* It's much easier to compare the number of blocks added with the number of
  blocks submitted to limit the maximum bio size.
* Even with bio chaining, we can keep adding blocks until we reach the maximum
  bio size, as long as we stop at a page boundary.  This simplifies the logic.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>

The Debian kernel v5.6 triggers this kernel panic:

 Kernel panic - not syncing: Bad Address (null pointer deref?)
 Bad Address (null pointer deref?): Code=26 (Data memory access rights trap) at addr 0000000000000000
 CPU: 0 PID: 0 Comm: swapper Not tainted 5.6.0-2-parisc64 #1 Debian 5.6.14-1
  IAOQ[0]: mem_init+0xb0/0x150
  IAOQ[1]: mem_init+0xb4/0x150
  RP(r2): start_kernel+0x6c8/0x1190
 Backtrace:
  [<0000000040101ab4>] start_kernel+0x6c8/0x1190
  [<0000000040108574>] start_parisc+0x158/0x1b8

on a HP-PARISC rp3440 machine with this memory layout:
 Memory Ranges:
  0) Start 0x0000000000000000 End 0x000000003fffffff Size   1024 MB
  1) Start 0x0000004040000000 End 0x00000040ffdfffff Size   3070 MB

Fix the crash by avoiding virt_to_page() and similar functions in
mem_init() until the memory zones have been fully set up.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v5.0+

kobject_init_and_add() takes reference even when it fails.
Thus, when kobject_init_and_add() returns an error,
kobject_put() must be called to properly clean up the kobject.

Fixes: d72e31c9 ("iommu: IOMMU Groups")
Signed-off-by: Qiushi Wu <wu000273@umn.edu>
Link: https://lore.kernel.org/r/20200527210020.6522-1-wu000273@umn.eduSigned-off-by: Joerg Roedel <jroedel@suse.de>

We provided the right semantics on open drain lines being
by definition output but incidentally the irq set up function
would only allow IRQs on lines that were "not output".

Fix the semantics to allow output open drain lines to be used
for IRQs.
Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Tested-by: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Russell King <linux@armlinux.org.uk>
Cc: stable@vger.kernel.org # v5.3+
Link: https://lore.kernel.org/r/20200527140758.162280-1-linus.walleij@linaro.orgSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

syzkaller is picking up a bunch of crashes that look like this:

  Unrecoverable exception 380 at c00000000037ed60 (msr=8000000000001031)
  Oops: Unrecoverable exception, sig: 6 [#1]
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in:
  CPU: 0 PID: 874 Comm: syz-executor.0 Not tainted 5.7.0-rc7-syzkaller-00016-gb0c3ba31 #0
  NIP:  c00000000037ed60 LR: c00000000004bac8 CTR: c000000000030990
  REGS: c0000000555a7230 TRAP: 0380   Not tainted  (5.7.0-rc7-syzkaller-00016-gb0c3ba31)
  MSR:  8000000000001031 <SF,ME,IR,DR,LE>  CR: 48222882  XER: 20000000
  CFAR: c00000000004bac4 IRQMASK: 0
  GPR00: c00000000004bb68 c0000000555a74c0 c0000000024b3500 0000000000000005
  GPR04: 0000000000000000 0000000000000000 c00000000004bb88 c008000000910000
  GPR08: 00000000000b0000 c00000000004bac8 0000000000016000 c000000002503500
  GPR12: c000000000030990 c000000003190000 00000000106a5898 00000000106a0000
  GPR16: 00000000106a5890 c000000007a92000 c000000008180e00 c000000007a8f700
  GPR20: c000000007a904b0 0000000010110000 c00000000259d318 5deadbeef0000100
  GPR24: 5deadbeef0000122 c000000078422700 c000000009ee88b8 c000000078422778
  GPR28: 0000000000000001 800000000280b033 0000000000000000 c0000000555a75a0
  NIP [c00000000037ed60] __sanitizer_cov_trace_pc+0x40/0x50
  LR [c00000000004bac8] interrupt_exit_kernel_prepare+0x118/0x310
  Call Trace:
  [c0000000555a74c0] [c00000000004bb68] interrupt_exit_kernel_prepare+0x1b8/0x310 (unreliable)
  [c0000000555a7530] [c00000000000f9a8] interrupt_return+0x118/0x1c0
  --- interrupt: 900 at __sanitizer_cov_trace_pc+0x0/0x50
  ...<random previous call chain>...

This is caused by __sanitizer_cov_trace_pc() causing an SLB fault
after MSR[RI] has been cleared by __hard_EE_RI_disable(), which we
can not recover from.

Do not instrument the new syscall/interrupt entry/exit code with KCOV,
GCOV or UBSAN.
Reported-by: syzbot-ppc64 <ozlabsyz@au1.ibm.com>
Fixes: 68b34588 ("powerpc/64/sycall: Implement syscall entry/exit logic in C")
Signed-off-by: Daniel Axtens <dja@axtens.net>
Acked-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Two ingenic fixes, one for a wrong cast, the other for a typo in a
comparison
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20200528110944.hanv4qgc6w7whnj3@gilmour.lan

Merge misc fixes from Andrew Morton:
 "5 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  include/asm-generic/topology.h: guard cpumask_of_node() macro argument
  fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info()
  mm: remove VM_BUG_ON(PageSlab()) from page_mapcount()
  mm,thp: stop leaking unreleased file pages
  mm/z3fold: silence kmemleak false positives of slots

Pull input fixes from Dmitry Torokhov:
 "Just a few random driver fixups"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: synaptics - add a second working PNP_ID for Lenovo T470s
  Input: applespi - replace zero-length array with flexible-array
  Input: axp20x-pek - always register interrupt handlers
  Input: lm8333 - update contact email
  Input: synaptics-rmi4 - fix error return code in rmi_driver_probe()
  Input: synaptics-rmi4 - really fix attn_data use-after-free
  Input: i8042 - add ThinkPad S230u to i8042 reset list
  Revert "Input: i8042 - add ThinkPad S230u to i8042 nomux list"
  Input: dlink-dir685-touchkeys - fix a typo in driver name
  Input: xpad - add custom init packet for Xbox One S controllers
  Input: evdev - call input_flush_device() on release(), not flush()
  Input: i8042 - add ThinkPad S230u to i8042 nomux list
  Input: usbtouchscreen - add support for BonXeon TP
  Input: cros_ec_keyb - use cros_ec_cmd_xfer_status helper
  Input: mms114 - fix handling of mms345l
  Input: elants_i2c - support palm detection

Pull csky fixes from Guo Ren:
 "Another four fixes for csky:

   - fix req_syscall debug

   - fix abiv2 syscall_trace

   - fix preempt enable

   - clean up regs usage in entry.S"

* tag 'csky-for-linus-5.7-rc8' of git://github.com/c-sky/csky-linux:
  csky: Fixup CONFIG_DEBUG_RSEQ
  csky: Coding convention in entry.S
  csky: Fixup abiv2 syscall_trace break a4 & a5
  csky: Fixup CONFIG_PREEMPT panic

This reverts commit c58c1f83.

io_uring does do the right thing for this case, and we're still returning
-EAGAIN to userspace for the cases we don't support. Revert this change
to avoid doing endless spins of resubmits.

Cc: stable@vger.kernel.org # v5.6
Reported-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/hwmon/amd_energy.c:195:15: error: invalid operands to binary expression ('void' and 'int')
                                        (channel - data->nr_cpus));
                                        ~~~~~~~~~^~~~~~~~~~~~~~~~~
include/asm-generic/topology.h:51:42: note: expanded from macro 'cpumask_of_node'
    #define cpumask_of_node(node)       ((void)node, cpu_online_mask)
                                               ^~~~
include/linux/cpumask.h:618:72: note: expanded from macro 'cpumask_first_and'
 #define cpumask_first_and(src1p, src2p) cpumask_next_and(-1, (src1p), (src2p))
                                                                       ^~~~~

Fixes: f0b848ce ("cpumask: Introduce cpumask_of_{node,pcibus} to replace {node,pcibus}_to_cpumask")
Fixes: 8abee956 ("hwmon: Add amd_energy driver to report energy counters")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: http://lkml.kernel.org/r/20200527134623.930247-1-arnd@arndb.deSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

KMSAN reported uninitialized data being written to disk when dumping
core.  As a result, several kilobytes of kmalloc memory may be written
to the core file and then read by a non-privileged user.
Reported-by: sam <sunhaoyl@outlook.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200419100848.63472-1-glider@google.com
Link: https://github.com/google/kmsan/issues/76Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Replace superfluous VM_BUG_ON() with comment about correct usage.

Technically reverts commit 1d148e21 ("mm: add VM_BUG_ON_PAGE() to
page_mapcount()"), but context lines have changed.

Function isolate_migratepages_block() runs some checks out of lru_lock
when choose pages for migration.  After checking PageLRU() it checks
extra page references by comparing page_count() and page_mapcount().
Between these two checks page could be removed from lru, freed and taken
by slab.

As a result this race triggers VM_BUG_ON(PageSlab()) in page_mapcount().
Race window is tiny.  For certain workload this happens around once a
year.

    page:ffffea0105ca9380 count:1 mapcount:0 mapping:ffff88ff7712c180 index:0x0 compound_mapcount: 0
    flags: 0x500000000008100(slab|head)
    raw: 0500000000008100 dead000000000100 dead000000000200 ffff88ff7712c180
    raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000
    page dumped because: VM_BUG_ON_PAGE(PageSlab(page))
    ------------[ cut here ]------------
    kernel BUG at ./include/linux/mm.h:628!
    invalid opcode: 0000 [#1] SMP NOPTI
    CPU: 77 PID: 504 Comm: kcompactd1 Tainted: G        W         4.19.109-27 #1
    Hardware name: Yandex T175-N41-Y3N/MY81-EX0-Y3N, BIOS R05 06/20/2019
    RIP: 0010:isolate_migratepages_block+0x986/0x9b0

The code in isolate_migratepages_block() was added in commit
119d6d59 ("mm, compaction: avoid isolating pinned pages") before
adding VM_BUG_ON into page_mapcount().

This race has been predicted in 2015 by Vlastimil Babka (see link
below).

[akpm@linux-foundation.org: comment tweaks, per Hugh]
Fixes: 1d148e21 ("mm: add VM_BUG_ON_PAGE() to page_mapcount()")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/159032779896.957378.7852761411265662220.stgit@buzz
Link: https://lore.kernel.org/lkml/557710E1.6060103@suse.cz/
Link: https://lore.kernel.org/linux-mm/158937872515.474360.5066096871639561424.stgit@buzz/T/ (v1)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When collapse_file() calls try_to_release_page(), it has already isolated
the page: so if releasing buffers happens to fail (as it sometimes does),
remember to putback_lru_page(): otherwise that page is left unreclaimable
and unfreeable, and the file extent uncollapsible.

Fixes: 99cb0dbd ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: <stable@vger.kernel.org>	[5.4+]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2005231837500.1766@eggly.anvilsSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>