Unmasking a fifo event channel can result in unmasking it twice, once
directly in the kernel and once via a hypercall in case the event was
pending.

Fix that by doing the local unmask only if the event is not pending.

This is part of XSA-332.

Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

A follow-up patch will require certain write to happen before an event
channel is unmasked.

While the memory barrier is not strictly necessary for all the callers,
the main one will need it. In order to avoid an extra memory barrier
when using fifo event channels, mandate evtchn_unmask() to provide
write ordering.

The 2-level event handling unmask operation is missing an appropriate
barrier, so add it. Fifo event channels are fine in this regard due to
using sync_cmpxchg().

This is part of XSA-332.

Cc: stable@vger.kernel.org
Suggested-by: Julien Grall <julien@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Wei Liu <wl@xen.org>

Today it can happen that an event channel is being removed from the
system while the event handling loop is active. This can lead to a
race resulting in crashes or WARN() splats when trying to access the
irq_info structure related to the event channel.

Fix this problem by using a rwlock taken as reader in the event
handling loop and as writer when deallocating the irq_info structure.

As the observed problem was a NULL dereference in evtchn_from_irq()
make this function more robust against races by testing the irq_info
pointer to be not NULL before dereferencing it.

And finally make all accesses to evtchn_to_irq[row][col] atomic ones
in order to avoid seeing partial updates of an array element in irq
handling. Note that irq handling can be entered only for event channels
which have been valid before, so any not populated row isn't a problem
in this regard, as rows are only ever added and never removed.

This is XSA-331.

Cc: stable@vger.kernel.org
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reported-by: Jinoh Kang <luke1337@theori.io>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Wei Liu <wl@xen.org>

Fix typo in xen_pagetable_p2m_free(): s/Fortunatly/Fortunately
Signed-off-by: Hui Su <sh_def@163.com>
Link: https://lore.kernel.org/r/20200927172836.GA7423@rlk

[boris: reword commit message slightly]
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

When running as Xen dom0 the kernel isn't responsible for selecting the
error handling mode, this should be handled by the hypervisor.

So disable setting FF mode when running as Xen pv guest. Not doing so
might result in boot splats like:

[    7.509696] HEST: Enabling Firmware First mode for corrected errors.
[    7.510382] mce: [Firmware Bug]: Ignoring request to disable invalid MCA bank 2.
[    7.510383] mce: [Firmware Bug]: Ignoring request to disable invalid MCA bank 3.
[    7.510384] mce: [Firmware Bug]: Ignoring request to disable invalid MCA bank 4.
[    7.510384] mce: [Firmware Bug]: Ignoring request to disable invalid MCA bank 5.
[    7.510385] mce: [Firmware Bug]: Ignoring request to disable invalid MCA bank 6.
[    7.510386] mce: [Firmware Bug]: Ignoring request to disable invalid MCA bank 7.
[    7.510386] mce: [Firmware Bug]: Ignoring request to disable invalid MCA bank 8.

Reason is that the HEST ACPI table contains the real number of MCA
banks, while the hypervisor is emulating only 2 banks for guests.

Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20200925140751.31381-1-jgross@suse.comSigned-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

The VCPUOP_register_runstate_memory_area hypercall takes a virtual
address of a buffer as a parameter. The semantics of the hypercall are
such that the virtual address should always be valid.

When KPTI is enabled and we are running userspace code, the virtual
address is not valid, thus, Linux is violating the semantics of
VCPUOP_register_runstate_memory_area.

Do not call VCPUOP_register_runstate_memory_area when KPTI is enabled.
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
CC: Bertrand Marquis <Bertrand.Marquis@arm.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
Link: https://lore.kernel.org/r/20200924234955.15455-1-sstabellini@kernel.orgReviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

After commit 9f51c05d ("pvcalls-front: Avoid
get_free_pages(GFP_KERNEL) under spinlock"), the variable ret is being
initialized with '-ENOMEM' that is meaningless. So remove it.
Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
Link: https://lore.kernel.org/r/20200919031702.32192-1-jingxiangfeng@huawei.comReviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

In 2019, we introduced pin_user_pages*() and now we are converting
get_user_pages*() to the new API as appropriate. [1] & [2] could
be referred for more information. This is case 5 as per document [1].

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
        https://lwn.net/Articles/807108/Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Link: https://lore.kernel.org/r/1599375114-32360-2-git-send-email-jrdr.linux@gmail.comReviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

There seems to be a bug in the original code when gntdev_get_page()
is called with writeable=true then the page needs to be marked dirty
before being put.

To address this, a bool writeable is added in gnt_dev_copy_batch, set
it in gntdev_grant_copy_seg() (and drop `writeable` argument to
gntdev_get_page()) and then, based on batch->writeable, use
set_page_dirty_lock().

Fixes: a4cdb556 (xen/gntdev: add ioctl for grant copy)
Suggested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1599375114-32360-1-git-send-email-jrdr.linux@gmail.comReviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Pull kvm fixes from Paolo Bonzini:
 "Two bugfixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: VMX: update PFEC_MASK/PFEC_MATCH together with PF intercept
  KVM: arm64: Restore missing ISB on nVHE __tlb_switch_to_guest

Pull xen fix from Juergen Gross:
 "Fix a regression introduced in 5.9-rc3 which caused a system running
  as fully virtualized guest under Xen to crash when using legacy
  devices like a floppy"

* tag 'for-linus-5.9b-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/events: don't use chip_data for legacy IRQs

Pull USB/PHY fixes from Greg KH:
 "Here are some small USB and PHY driver fixes for 5.9-rc8

  The PHY driver fix resolves an issue found by Dan Carpenter for a
  memory leak.

  The USB fixes fall into two groups:

   - usb gadget fix from Bryan that is a fix for a previous security fix
     that showed up in in-the-wild testing

   - usb core driver matching bugfixes. This fixes a bug that has
     plagued the both the usbip driver and syzbot testing tools this -rc
     release cycle. All is now working properly so usbip connections
     will work, and syzbot can get back to fuzzing USB drivers properly.

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

* tag 'usb-5.9-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usbcore/driver: Accommodate usbip
  usbcore/driver: Fix incorrect downcast
  usbcore/driver: Fix specific driver selection
  Revert "usbip: Implement a match function to fix usbip"
  USB: gadget: f_ncm: Fix NDP16 datagram validation
  phy: ti: am654: Fix a leak in serdes_am654_probe()

Pull i2c fixes from Wolfram Sang:
 "Some more driver fixes for i2c"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: npcm7xx: Clear LAST bit after a failed transaction.
  i2c: cpm: Fix i2c_ram structure
  i2c: i801: Exclude device from suspend direct complete optimization

Pull input fixes from Dmitry Torokhov:
 "A couple more driver quirks, now enabling newer trackpoints from
  Synaptics for real"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: i8042 - add nopnp quirk for Acer Aspire 5 A515
  Input: trackpoint - enable Synaptics trackpoints

One of the entries has three fields "mistake||correction||correction"
rather than the expected two fields "mistake||correction".  Fix it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200930234359.255295-1-ebiggers@kernel.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memalloc_nocma_{save/restore} APIs can be used to skip page allocation
on CMA area, but, there is a missing case and the page on CMA area could
be allocated even if APIs are used.  This patch handles this case to fix
the potential issue.

For now, these APIs are used to prevent long-term pinning on the CMA
page.  When the long-term pinning is requested on the CMA page, it is
migrated to the non-CMA page before pinning.  This non-CMA page is
allocated by using memalloc_nocma_{save/restore} APIs.  If APIs doesn't
work as intended, the CMA page is allocated and it is pinned for a long
time.  This long-term pin for the CMA page causes cma_alloc() failure
and it could result in wrong behaviour on the device driver who uses the
cma_alloc().

Missing case is an allocation from the pcplist.  MIGRATE_MOVABLE pcplist
could have the pages on CMA area so we need to skip it if ALLOC_CMA
isn't specified.

Fixes: 8510e69c (mm/page_alloc: fix memalloc_nocma_{save/restore} APIs)
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Link: https://lkml.kernel.org/r/1601429472-12599-1-git-send-email-iamjoonsoo.kim@lge.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The routine that applies debug flags to the kmem_cache slabs
inadvertantly prevents non-debug flags from being applied to those
same objects.  That is, if slub_debug=<flag>,<slab> is specified,
non-debugged slabs will end up having flags of zero, and the slabs
may be unusable.

Fix this by including the input flags for non-matching slabs with the
contents of slub_debug, so that the caches are created as expected
alongside any debugging options that may be requested.  With this, we
can remove the check for a NULL slub_debug_string, since it's covered
by the loop itself.

Fixes: e17f1dfb ("mm, slub: extend slub_debug syntax for multiple blocks")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Link: https://lkml.kernel.org/r/20200930161931.28575-1-farman@linux.ibm.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'kvmarm-fixes-5.9-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-master

KVM/arm64 fixes for 5.9, take #3

- Fix synchronization of VTTBR update on TLB invalidation for nVHE systems

The PFEC_MASK and PFEC_MATCH fields in the VMCS reverse the meaning of
the #PF intercept bit in the exception bitmap when they do not match.
This means that, if PFEC_MASK and/or PFEC_MATCH are set, the
hypervisor can get a vmexit for #PF exceptions even when the
corresponding bit is clear in the exception bitmap.

This is unexpected and is promptly detected by a WARN_ON_ONCE.
To fix it, reset PFEC_MASK and PFEC_MATCH when the #PF intercept
is disabled (as is common with enable_ept && !allow_smaller_maxphyaddr).
Reported-by: Qian Cai <cai@redhat.com&gt;>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Pull pin control fixes from Linus Walleij:
 "Some pin control fixes here. All of them are driver fixes, the Intel
  Cherryview being the most interesting one.

   - Fix a mux problem for I2C in the MVEBU driver.

   - Fix a really hairy inversion problem in the Intel Cherryview
     driver.

   - Fix the register for the sdc2_clk in the Qualcomm SM8250 driver.

   - Check the virtual GPIO boot failur in the Mediatek driver"

* tag 'pinctrl-v5.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: mediatek: check mtk_is_virt_gpio input parameter
  pinctrl: qcom: sm8250: correct sdc2_clk
  pinctrl: cherryview: Preserve CHV_PADCTRL1_INVRXTX_TXDATA flag on GPIOs
  pinctrl: mvebu: Fix i2c sda definition for 98DX3236

Pull PCI fixes from Bjorn Helgaas:

 - Fix rockchip regression in rockchip_pcie_valid_device() (Lorenzo
   Pieralisi)

 - Add Pali Rohár as aardvark PCI maintainer (Pali Rohár)

* tag 'pci-v5.9-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  MAINTAINERS: Add Pali Rohár as aardvark PCI maintainer
  PCI: rockchip: Fix bus checks in rockchip_pcie_valid_device()

Pull SCSI fixes from James Bottomley:
 "Two patches in driver frameworks. The iscsi one corrects a bug induced
  by a BPF change to network locking and the other is a regression we
  introduced"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: iscsi: iscsi_tcp: Avoid holding spinlock while calling getpeername()
  scsi: target: Fix lun lookup for TARGET_SCF_LOOKUP_LUN_FROM_TAG case

Pull io_uring fixes from Jens Axboe:

 - fix for async buffered reads if read-ahead is fully disabled (Hao)

 - double poll match fix

 - ->show_fdinfo() potential ABBA deadlock complaint fix

* tag 'io_uring-5.9-2020-10-02' of git://git.kernel.dk/linux-block:
  io_uring: fix async buffered reads when readahead is disabled
  io_uring: fix potential ABBA deadlock in ->show_fdinfo()
  io_uring: always delete double poll wait entry on match

Pull block fix from Jens Axboe:
 "Single fix for a ->commit_rqs failure case"

* tag 'block-5.9-2020-10-02' of git://git.kernel.dk/linux-block:
  blk-mq: call commit_rqs while list empty but error happen

Pull epoll fixes from Al Viro:
 "Several race fixes in epoll"

* 'work.epoll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  ep_create_wakeup_source(): dentry name can change under you...
  epoll: EPOLL_CTL_ADD: close the race in decision to take fast path
  epoll: replace ->visited/visited_list with generation count
  epoll: do not insert into poll queues until all sanity checks are done

Pull RISC-V fixes from Palmer Dabbelt:
 "Two fixes for this week:

   - The addition of a symbol export for clint_time_val, which has been
     inlined into some timex functions and can be used by drivers.

   - A fix to avoid calling get_cycles() before the timers have been
     probed.

  These both only effect !MMU systems"

* tag 'riscv-for-linus-5.9-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  RISC-V: Check clint_time_val before use
  clocksource: clint: Export clint_time_val for modules

Pull btrfs fixes from David Sterba:
 "Two more fixes.

  One is for a lockdep warning/lockup (also caught by syzbot), that one
  has been seen in practice. Regarding the other syzbot reports
  mentioned last time, they don't seem to be urgent and reliably
  reproducible so they'll be fixed later.

  The second fix is for a potential corruption when device replace
  finishes and the in-memory state of trim is not copied to the new
  device"

* tag 'for-5.9-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix filesystem corruption after a device replace
  btrfs: move btrfs_rm_dev_replace_free_srcdev outside of all locks
  btrfs: move btrfs_scratch_superblocks into btrfs_dev_replace_finishing

Pull power management fixes from Rafael Wysocki:
 "These fix one more issue related to the recent RCU-lockdep changes, a
  typo in documentation and add a missing return statement to
  intel_pstate.

  Specifics:

   - Fix up RCU usage for cpuidle on the ARM imx6q platform (Ulf
     Hansson)

   - Fix typo in the PM documentation (Yoann Congal)

   - Add return statement that is missing after recent changes in the
     intel_pstate driver (Zhang Rui)"

* tag 'pm-5.9-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ARM: imx6q: Fixup RCU usage for cpuidle
  Documentation: PM: Fix a reStructuredText syntax error
  cpufreq: intel_pstate: Fix missing return statement

Pull IIO fixes from Greg KH:
 "Here are two small IIO driver fixes for 5.9-rc8 that resolve some
  reported issues:

   - driver name fixed in one driver

   - device name typo fixed

  Both have been in linux-next for a while with no reported problems"

* tag 'staging-5.9-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  iio: adc: qcom-spmi-adc5: fix driver name
  iio: adc: ad7124: Fix typo in device name

Pull GPIO fixes from Linus Walleij:
 "Some late GPIO fixes for the v5.9 series:

   - Fix compiler warnings on the OMAP when PM is disabled

   - Clear the interrupt when setting edge sensitivity on the Spreadtrum
     driver.

   - Fix up spurious interrupts on the TC35894.

   - Support threaded interrupts on the Siox controller.

   - Fix resource leaks on the mockup driver.

   - Fix line event handling in syscall compatible mode for the
     character device.

   - Fix an unitialized variable in the PCA953A driver.

   - Fix access to all GPIO IRQs on the Aspeed AST2600.

   - Fix line direction on the AMD FCH driver.

   - Use the bitmap API instead of compiler intrinsics for bit
     manipulation in the PCA953x driver"

* tag 'gpio-v5.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: pca953x: Correctly initialize registers 6 and 7 for PCA957x
  gpio: pca953x: Use bitmap API over implicit GCC extension
  gpio: amd-fch: correct logic of GPIO_LINE_DIRECTION
  gpio: aspeed: fix ast2600 bank properties
  gpio/aspeed-sgpio: don't enable all interrupts by default
  gpio/aspeed-sgpio: enable access to all 80 input & output sgpios
  gpio: pca953x: Fix uninitialized pending variable
  gpiolib: Fix line event handling in syscall compatible mode
  gpio: mockup: fix resource leak in error path
  gpio: siox: explicitly support only threaded irqs
  gpio: tc35894: fix up tc35894 interrupt configuration
  gpio: sprd: Clear interrupt when setting the type as edge
  gpio: omap: Fix warnings if PM is disabled

Pull MMC fixes from Ulf Hansson:

 - Fix deadlock when removing MEMSTICK host

 - Workaround broken CMDQ on Intel GLK based IRBIS models

* tag 'mmc-v5.9-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: sdhci: Workaround broken command queuing on Intel GLK based IRBIS models
  memstick: Skip allocating card when removing host

Commit f227e3ec ("random32: update the net random state on interrupt
and activity") broke compilation and was temporarily fixed by Linus in
83bdc727 ("random32: remove net_rand_state from the latent entropy
gcc plugin") by entirely moving net_rand_state out of the things handled
by the latent_entropy GCC plugin.

From what I understand when reading the plugin code, using the
__latent_entropy attribute on a declaration was the wrong part and
simply keeping the __latent_entropy attribute on the variable definition
was the correct fix.

Fixes: 83bdc727 ("random32: remove net_rand_state from the latent entropy gcc plugin")
Acked-by: Willy Tarreau <w@1wt.eu>
Cc: Emese Revfy <re.emese@gmail.com>
Signed-off-by: Thibaut Sautereau <thibaut.sautereau@ssi.gouv.fr>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* pm-cpufreq:
  cpufreq: intel_pstate: Fix missing return statement

Since commit ea426c2a ("mm: memcg: prepare for byte-sized vmstat
items") the write side of slab counters accepts a value in bytes and
converts it to pages.  It happens in __mod_node_page_state().

However a non-SMP version of __mod_node_page_state() doesn't perform
this conversion.  It leads to incorrect (unrealistically high) slab
counters values.  Fix this by adding a similar conversion to the non-SMP
version of __mod_node_page_state().
Signed-off-by: Roman Gushchin <guro@fb.com>
Reported-and-tested-by: Bastian Bittorf <bb@npl.de>
Fixes: ea426c2a ("mm: memcg: prepare for byte-sized vmstat items")
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The pipe splice code still used the old model of waiting for pipe IO by
using a non-specific "pipe_wait()" that waited for any pipe event to
happen, which depended on all pipe IO being entirely serialized by the
pipe lock.  So by checking the state you were waiting for, and then
adding yourself to the wait queue before dropping the lock, you were
guaranteed to see all the wakeups.

Strictly speaking, the actual wakeups were not done under the lock, but
the pipe_wait() model still worked, because since the waiter held the
lock when checking whether it should sleep, it would always see the
current state, and the wakeup was always done after updating the state.

However, commit 0ddad21d ("pipe: use exclusive waits when reading or
writing") split the single wait-queue into two, and in the process also
made the "wait for event" code wait for _two_ wait queues, and that then
showed a race with the wakers that were not serialized by the pipe lock.

It's only splice that used that "pipe_wait()" model, so the problem
wasn't obvious, but Josef Bacik reports:

 "I hit a hang with fstest btrfs/187, which does a btrfs send into
  /dev/null. This works by creating a pipe, the write side is given to
  the kernel to write into, and the read side is handed to a thread that
  splices into a file, in this case /dev/null.

  The box that was hung had the write side stuck here [pipe_write] and
  the read side stuck here [splice_from_pipe_next -> pipe_wait].

  [ more details about pipe_wait() scenario ]

  The problem is we're doing the prepare_to_wait, which sets our state
  each time, however we can be woken up either with reads or writes. In
  the case above we race with the WRITER waking us up, and re-set our
  state to INTERRUPTIBLE, and thus never break out of schedule"

Josef had a patch that avoided the issue in pipe_wait() by just making
it set the state only once, but the deeper problem is that pipe_wait()
depends on a level of synchonization by the pipe mutex that it really
shouldn't.  And the whole "wait for any pipe state change" model really
isn't very good to begin with.

So rather than trying to work around things in pipe_wait(), remove that
legacy model of "wait for arbitrary pipe event" entirely, and actually
create functions that wait for the pipe actually being readable or
writable, and can do so without depending on the pipe lock serializing
everything.

Fixes: 0ddad21d ("pipe: use exclusive waits when reading or writing")
Link: https://lore.kernel.org/linux-fsdevel/bfa88b5ad6f069b2b679316b9e495a970130416c.1601567868.git.josef@toxicpanda.com/Reported-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-and-tested-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull iommu fixes from Joerg Roedel:

 - Fix a device reference counting bug in the Exynos IOMMU driver.

 - Lockdep fix for the Intel VT-d driver.

 - Fix a bug in the AMD IOMMU driver which caused corruption of the IVRS
   ACPI table and caused IOMMU driver initialization failures in kdump
   kernels.

* tag 'iommu-fixes-v5.9-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/vt-d: Fix lockdep splat in iommu_flush_dev_iotlb()
  iommu/amd: Fix the overwritten field in IVMD header
  iommu/exynos: add missing put_device() call in exynos_iommu_of_xlate()

Pull arm64 fix from Catalin Marinas:
 "A previous commit to prevent AML memory opregions from accessing the
  kernel memory turned out to be too restrictive. Relax the permission
  check to permit the ACPI core to map kernel memory used for table
  overrides"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: permit ACPI core to map kernel memory used for table overrides

Pull drm fixes from Dave Airlie:
 "AMD and vmwgfx fixes.

  Just dequeuing these a bit early as the AMD ones are bit larger than
  I'd prefer, but Alex missed last week so it's a double set of fixes.
  The larger ones are just register header fixes for the new chips that
  were just introduced in rc1 along with some new PCI IDs for new hw.
  Otherwise it is usual fixes.

  The vmwgfx fix was due to some testing I was doing and found we
  weren't booting properly, vmware had the fix internally so hurried it

  vmwgfx:
   - fix a regression due to TTM refactor

  amdgpu:
   - Fix potential double free in userptr handling
   - Sienna Cichlid and Navy Flounder udpates
   - Add Sienna Cichlid PCI IDs
   - Drop experimental flag for navi12
   - Raven fixes
   - Renoir fixes
   - HDCP fix
   - DCN3 fix for clang and older versions of gcc
   - Fix a runtime pm refcount issue"

* tag 'drm-fixes-2020-10-01-1' of git://anongit.freedesktop.org/drm/drm:
  drm/amdgpu: disable gfxoff temporarily for navy_flounder
  drm/amd/pm: setup APU dpm clock table in SMU HW initialization
  drm/vmwgfx: Fix error handling in get_node
  drm/amd/display: remove duplicate call to rn_vbios_smu_get_smu_version()
  drm/amdgpu/swsmu/smu12: fix force clock handling for mclk
  drm/amdgpu: restore proper ref count in amdgpu_display_crtc_set_config
  drm/amdgpu/display: fix CFLAGS setup for DCN30
  drm/amd/display: fix return value check for hdcp_work
  drm/amdgpu: remove gpu_info fw support for sienna_cichlid etc.
  drm/amd/pm: Removed fixed clock in auto mode DPM
  drm/amdgpu: remove experimental flag from navi12
  drm/amdgpu: add device ID for sienna_cichlid (v2)
  drm/amdgpu: use the AV1 defines for VCN 3.0
  drm/amdgpu: add VCN 3.0 AV1 registers
  drm/amdgpu: add the GC 10.3 VRS registers
  drm/amdgpu: prevent double kfree ttm->sg

Pull tracing fixes from Steven Rostedt:
 "Two tracing fixes:

   - Fix temp buffer accounting that caused a WARNING for
     ftrace_dump_on_opps()

   - Move the recursion check in one of the function callback helpers to
     the beginning of the function, as if the rcu_is_watching() gets
     traced, it will cause a recursive loop that will crash the kernel"

* tag 'trace-v5.9-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace: Move RCU is watching check after recursion check
  tracing: Fix trace_find_next_entry() accounting of temp buffer size