Pull overlayfs fixes from Amir Goldstein:

 - Fix for file reference leak regression

 - Fix for NULL pointer deref regression

 - Fixes for RCU-walk race regressions:

   Two of the fixes were taken from Al's RCU pathwalk race fixes series
   with his consent [1].

   Note that unlike most of Al's series, these two patches are not about
   racing with ->kill_sb() and they are also very recent regressions
   from v6.5, so I think it's worth getting them into v6.5.y.

   There is also a fix for an RCU pathwalk race with ->kill_sb(), which
   may have been solved in vfs generic code as you suggested, but it
   also rids overlayfs from a nasty hack, so I think it's worth anyway.

Link: https://lore.kernel.org/linux-fsdevel/20231003204749.GA800259@ZenIV/ [1]

* tag 'ovl-fixes-6.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
  ovl: fix NULL pointer defer when encoding non-decodable lower fid
  ovl: make use of ->layers safe in rcu pathwalk
  ovl: fetch inode once in ovl_dentry_revalidate_common()
  ovl: move freeing ovl_entry past rcu delay
  ovl: fix file reference leak when submitting aio

Pull rtla fixes from Daniel Bristot de Oliveira:
 "rtla (Real-Time Linux Analysis) tool fixes.

  Timerlat auto-analysis:

   - Timerlat is reporting thread interference time without thread noise
     events occurrence. It was caused because the thread interference
     variable was not reset after the analysis of a timerlat activation
     that did not hit the threshold.

   - The IRQ handler delay is estimated from the delta of the IRQ
     latency reported by timerlat, and the timestamp from IRQ handler
     start event. If the delta is near-zero, the drift from the external
     clock and the trace event and/or the overhead can cause the value
     to be negative. If the value is negative, print a zero-delay.

   - IRQ handlers happening after the timerlat thread event but before
     the stop tracing were being reported as IRQ that happened before
     the *current* IRQ occurrence. Ignore Previous IRQ noise in this
     condition because they are valid only for the *next* timerlat
     activation.

  Timerlat user-space:

   - Timerlat is stopping all user-space thread if a CPU becomes
     offline. Do not stop the entire tool if a CPU is/become offline,
     but only the thread of the unavailable CPU. Stop the tool only, if
     all threads leave because the CPUs become/are offline.

  man-pages:

   - Fix command line example in timerlat hist man page"

* tag 'rtla-v6.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bristot/linux:
  rtla: fix a example in rtla-timerlat-hist.rst
  rtla/timerlat: Do not stop user-space if a cpu is offline
  rtla/timerlat_aa: Fix previous IRQ delay for IRQs that happens after thread sample
  rtla/timerlat_aa: Fix negative IRQ delay
  rtla/timerlat_aa: Zero thread sum after every sample analysis

Merge tag 'linux-kselftest-fixes-6.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull kselftest fix from Shuah Khan:
 "One single fix to Makefile to fix the incorrect TARGET name for uevent
  test"

* tag 'linux-kselftest-fixes-6.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  selftests: Fix wrong TARGET in kselftest top level Makefile

Pull NFS client fixes from Anna Schumaker:
 "Stable fixes:
   - Revert "SUNRPC dont update timeout value on connection reset"
   - NFSv4: Fix a state manager thread deadlock regression

  Fixes:
   - Fix potential NULL pointer dereference in nfs_inode_remove_request()
   - Fix rare NULL pointer dereference in xs_tcp_tls_setup_socket()
   - Fix long delay before failing a TLS mount when server does not
     support TLS
   - Fix various NFS state manager issues"

* tag 'nfs-for-6.6-3' of git://git.linux-nfs.org/projects/anna/linux-nfs:
  nfs: decrement nrequests counter before releasing the req
  SUNRPC/TLS: Lock the lower_xprt during the tls handshake
  Revert "SUNRPC dont update timeout value on connection reset"
  NFSv4: Fix a state manager thread deadlock regression
  NFSv4: Fix a nfs4_state_manager() race
  SUNRPC: Fail quickly when server does not recognize TLS

Merge tag 'regulator-fix-v6.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator

Pull regulator fixes from Mark Brown:
 "Two things here, one is an improved fix for issues around freeing
  devices when registration fails which replaces a half baked fix with a
  more complete one which uses the device model release() function
  properly.

  The other fix is a device specific fix for mt6358, the driver said
  that the LDOs supported mode configuration but this is not actually
  the case and could cause issues"

* tag 'regulator-fix-v6.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator/core: Revert "fix kobject release warning and memory leak in regulator_register()"
  regulator/core: regulator_register: set device->class earlier
  regulator: mt6358: split ops for buck and linear range LDO regulators

Pull regmap fix from Mark Brown:
 "A fix for a long standing issue where when we create a new node in an
  rbtree register cache we were failing to convert the register address
  of the new register into a bitmask correctly and marking the wrong
  register as being present in the newly created node.

  This would only have affected devices with a register stride other
  than 1 but would corrupt data on those devices"

* tag 'regmap-fix-v6.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: rbtree: Fix wrong register marked as in-cache when creating new node

Pull SCSI fixes from James Bottomley:
 "Three fixes, all in drivers.

  The fnic one is the most extensive because the little used user
  initiated device reset path never tagged the command and adding a tag
  is rather involved. The other two fixes are smaller and more obvious"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: zfcp: Fix a double put in zfcp_port_enqueue()
  scsi: fnic: Fix sg_reset success path
  scsi: target: core: Fix deadlock due to recursive locking

A wrong return value from ovl_check_encode_origin() would cause
ovl_dentry_to_fid() to try to encode fid from NULL upper dentry.

Reported-by: syzbot+2208f82282740c1c8915@syzkaller.appspotmail.com
Fixes: 16aac5ad ("ovl: support encoding non-decodable file handles")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Pull UBI fix from Richard Weinberger:

 - Don't try to attach MTDs with erase block size 0

* tag 'ubifs-for-linus-6.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs:
  ubi: Refuse attaching if mtd's erasesize is 0

Pull libnvdimm fix from Dave Jiang:

 - Fix incorrect calculation of idt size in NFIT

* tag 'libnvdimm-fixes-6.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  ACPI: NFIT: Fix incorrect calculation of idt size

Pull iommu fixes from Joerg Roedel:

 - Arm SMMU fixes from Will Deacon:
     - Fix TLB range command encoding when TTL, Num and Scale are all zero
     - Fix soft lockup by limiting TLB invalidation ops issued by SVA
     - Fix clocks description for SDM630 platform in arm-smmu DT binding

 - Intel VT-d fix from Lu Baolu:
     - Fix a suspend/hibernation problem in iommu_suspend()

 - Mediatek driver: Fix page table sharing for addresses over 4GiB

 - Apple/Dart: DMA_FQ handling fix in attach_dev()

* tag 'iommu-fixes-v6.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/vt-d: Avoid memory allocation in iommu_suspend()
  iommu/apple-dart: Handle DMA_FQ domains in attach_dev()
  iommu/mediatek: Fix share pgtable for iova over 4GB
  iommu/arm-smmu-v3: Fix soft lockup triggered by arm_smmu_mm_invalidate_range
  dt-bindings: arm-smmu: Fix SDM630 clocks description
  iommu/arm-smmu-v3: Avoid constructing invalid range commands

ovl_permission() accesses ->layers[...].mnt; we can't have ->layers
freed without an RCU delay on fs shutdown.

Fortunately, kern_unmount_array() that is used to drop those mounts
does include an RCU delay, so freeing is delayed; unfortunately, the
array passed to kern_unmount_array() is formed by mangling ->layers
contents and that happens without any delays.

The ->layers[...].name string entries are used to store the strings to
display in "lowerdir=..." by ovl_show_options().  Those entries are not
accessed in RCU walk.

Move the name strings into a separate array ofs->config.lowerdirs and
reuse the ofs->config.lowerdirs array as the temporary mount array to
pass to kern_unmount_array().
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20231002023711.GP3389589@ZenIV/Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

d_inode_rcu() is right - we might be in rcu pathwalk;
however, OVL_E() hides plain d_inode() on the same dentry...

Fixes: a6ff2bc0 ("ovl: use OVL_E() and OVL_E_FLAGS() accessors")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

... into ->free_inode(), that is.

Fixes: 0af950f5 "ovl: move ovl_entry into ovl_inode"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Commit 724768a3 ("ovl: fix incorrect fdput() on aio completion")
took a refcount on real file before submitting aio, but forgot to
avoid clearing FDPUT_FPUT from real.flags stack variable.
This can result in a file reference leak.

Fixes: 724768a3 ("ovl: fix incorrect fdput() on aio completion")
Reported-by: Gil Lev <contact@levgil.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Merge tag 'kbuild-fixes-v6.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix the module compression with xz so the in-kernel decompressor
   works

 - Document a kconfig idiom to express an optional dependency between
   modules

 - Make modpost, when W=1 is given, detect broken drivers that reference
   .exit.* sections

 - Remove unused code

* tag 'kbuild-fixes-v6.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: remove stale code for 'source' symlink in packaging scripts
  modpost: Don't let "driver"s reference .exit.*
  vmlinux.lds.h: remove unused CPU_KEEP and CPU_DISCARD macros
  modpost: add missing else to the "of" check
  Documentation: kbuild: explain handling optional dependencies
  kbuild: Use CRC32 and a 1MiB dictionary for XZ compressed modules

Merge tag 'mm-hotfixes-stable-2023-10-01-08-34' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "Fourteen hotfixes, eleven of which are cc:stable. The remainder
  pertain to issues which were introduced after 6.5"

* tag 'mm-hotfixes-stable-2023-10-01-08-34' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  Crash: add lock to serialize crash hotplug handling
  selftests/mm: fix awk usage in charge_reserved_hugetlb.sh and hugetlb_reparenting_test.sh that may cause error
  mm: mempolicy: keep VMA walk if both MPOL_MF_STRICT and MPOL_MF_MOVE are specified
  mm/damon/vaddr-test: fix memory leak in damon_do_test_apply_three_regions()
  mm, memcg: reconsider kmem.limit_in_bytes deprecation
  mm: zswap: fix potential memory corruption on duplicate store
  arm64: hugetlb: fix set_huge_pte_at() to work with all swap entries
  mm: hugetlb: add huge page size param to set_huge_pte_at()
  maple_tree: add MAS_UNDERFLOW and MAS_OVERFLOW states
  maple_tree: add mas_is_active() to detect in-tree walks
  nilfs2: fix potential use after free in nilfs_gccache_submit_read_data()
  mm: abstract moving to the next PFN
  mm: report success more often from filemap_map_folio_range()
  fs: binfmt_elf_efpic: fix personality for ELF-FDPIC

Pull misc driver fix from Greg KH:
 "Here is a single, much requested, fix for a set of misc drivers to
  resolve a much reported regression in the -rc series that has also
  propagated back to the stable releases. Sorry for the delay, lots of
  conference travel for a few weeks put me very far behind in patch
  wrangling.

  It has been reported by many to resolve the reported problem, and has
  been in linux-next with no reported issues"

* tag 'char-misc-6.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  misc: rtsx: Fix some platforms can not boot and move the l1ss judgment to probe

Pull tty / serial driver fixes from Greg KH:
 "Here are two tty/serial driver fixes for 6.6-rc4 that resolve some
  reported regressions:

   - revert a n_gsm change that ended up causing problems

   - 8250_port fix for irq data

  both have been in linux-next for over a week with no reported
  problems"

* tag 'tty-6.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  Revert "tty: n_gsm: fix UAF in gsm_cleanup_mux"
  serial: 8250_port: Check IRQ data before use

Pull x86 fixes from Ingo Molnar:
 "Misc fixes: a kerneldoc build warning fix, add SRSO mitigation for
  AMD-derived Hygon processors, and fix a SGX kernel crash in the page
  fault handler that can trigger when ksgxd races to reclaim the SECS
  special page, by making the SECS page unswappable"

* tag 'x86-urgent-2023-10-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sgx: Resolves SECS reclaim vs. page fault for EAUG race
  x86/srso: Add SRSO mitigation for Hygon processors
  x86/kgdb: Fix a kerneldoc warning when build with W=1

Pull timer fix from Ingo Molnar:
 "Fix a spurious kernel warning during CPU hotplug events that may
  trigger when timer/hrtimer softirqs are pending, which are otherwise
  hotplug-safe and don't merit a warning"

* tag 'timers-urgent-2023-10-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timers: Tag (hr)timer softirq as hotplug safe

Pull scheduler fix from Ingo Molnar:
 "Fix a RT tasks related lockup/live-lock during CPU offlining"

* tag 'sched-urgent-2023-10-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/rt: Fix live lock between select_fallback_rq() and RT push

Pull perf event fixes from Ingo Molnar:
 "Misc fixes: work around an AMD microcode bug on certain models, and
  fix kexec kernel PMI handlers on AMD systems that get loaded on older
  kernels that have an unexpected register state"

* tag 'perf-urgent-2023-10-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/amd: Do not WARN() on every IRQ
  perf/x86/amd/core: Fix overflow reset on hotplug

Since commit d8131c29 ("kbuild: remove $(MODLIB)/source symlink"),
modules_install does not create the 'source' symlink.

Remove the stale code from builddeb and kernel.spec.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Drivers must not reference functions marked with __exit as these likely
are not available when the code is built-in.

There are few creative offenders uncovered for example in ARCH=amd64
allmodconfig builds. So only trigger the section mismatch warning for
W=1 builds.

The dual rule that drivers must not reference .init.* is implemented
since commit 0db25245 ("modpost: don't allow *driver to reference
.init.*") which however missed that .exit.* should be handled in the
same way.

Thanks to Masahiro Yamada and Arnd Bergmann who gave valuable hints to
find this improvement.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Remove the left-over of commit e24f6628 ("modpost: remove all
traces of cpuinit/cpuexit sections").
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Paul Gortmaker <paul.gortmaker@windriver.com>

Without this 'else' statement, an "usb" name goes into two handlers:
the first/previous 'if' statement _AND_ the for-loop over 'devtable',
but the latter is useless as it has no 'usb' device_id entry anyway.

Tested with allmodconfig before/after patch; no changes to *.mod.c:

    git checkout v6.6-rc3
    make -j$(nproc) allmodconfig
    make -j$(nproc) olddefconfig

    make -j$(nproc)
    find . -name '*.mod.c' | cpio -pd /tmp/before

    # apply patch

    make -j$(nproc)
    find . -name '*.mod.c' | cpio -pd /tmp/after

    diff -r /tmp/before/ /tmp/after/
    # no difference

Fixes: acbef7b7 ("modpost: fix module autoloading for OF devices with generic compatible property")
Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Pull ARM SoC fixes from Arnd Bergmann:
 "These are the latest bug fixes that have come up in the soc tree. Most
  of these are fairly minor. Most notably, the majority of changes this
  time are not for dts files as usual.

   - Updates to the addresses of the broadcom and aspeed entries in the
     MAINTAINERS file.

   - Defconfig updates to address a regression on samsung and a build
     warning from an unknown Kconfig symbol

   - Build fixes for the StrongARM and Uniphier platforms

   - Code fixes for SCMI and FF-A firmware drivers, both of which had a
     simple bug that resulted in invalid data, and a lesser fix for the
     optee firmware driver

   - Multiple fixes for the recently added loongson/loongarch "guts" soc
     driver

   - Devicetree fixes for RISC-V on the startfive platform, addressing
     issues with NOR flash, usb and uart.

   - Multiple fixes for NXP i.MX8/i.MX9 dts files, fixing problems with
     clock, gpio, hdmi settings and the Makefile

   - Bug fixes for i.MX firmware code and the OCOTP soc driver

   - Multiple fixes for the TI sysc bus driver

   - Minor dts updates for TI omap dts files, to address boot time
     warnings and errors"

* tag 'soc-fixes-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (35 commits)
  MAINTAINERS: Fix Florian Fainelli's email address
  arm64: defconfig: enable syscon-poweroff driver
  ARM: locomo: fix locomolcd_power declaration
  soc: loongson: loongson2_guts: Remove unneeded semicolon
  soc: loongson: loongson2_guts: Convert to devm_platform_ioremap_resource()
  soc: loongson: loongson_pm2: Populate children syscon nodes
  dt-bindings: soc: loongson,ls2k-pmc: Allow syscon-reboot/syscon-poweroff as child
  soc: loongson: loongson_pm2: Drop useless of_device_id compatible
  dt-bindings: soc: loongson,ls2k-pmc: Use fallbacks for ls2k-pmc compatible
  soc: loongson: loongson_pm2: Add dependency for INPUT
  arm64: defconfig: remove CONFIG_COMMON_CLK_NPCM8XX=y
  ARM: uniphier: fix cache kernel-doc warnings
  MAINTAINERS: aspeed: Update Andrew's email address
  MAINTAINERS: aspeed: Update git tree URL
  firmware: arm_ffa: Don't set the memory region attributes for MEM_LEND
  arm64: dts: imx: Add imx8mm-prt8mm.dtb to build
  arm64: dts: imx8mm-evk: Fix hdmi@3d node
  soc: imx8m: Enable OCOTP clock for imx8mm before reading registers
  arm64: dts: imx8mp-beacon-kit: Fix audio_pll2 clock
  arm64: dts: imx8mp: Fix SDMA2/3 clocks
  ...

Pull tracing fixes from Steven Rostedt:

 - Make sure 32-bit applications using user events have aligned access
   when running on a 64-bit kernel.

 - Add cond_resched in the loop that handles converting enums in
   print_fmt string is trace events.

 - Fix premature wake ups of polling processes in the tracing ring
   buffer. When a task polls waiting for a percentage of the ring buffer
   to be filled, the writer still will wake it up at every event. Add
   the polling's percentage to the "shortest_full" list to tell the
   writer when to wake it up.

 - For eventfs dir lookups on dynamic events, an event system's only
   event could be removed, leaving its dentry with no children. This is
   totally legitimate. But in eventfs_release() it must not access the
   children array, as it is only allocated when the dentry has children.

* tag 'trace-v6.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  eventfs: Test for dentries array allocated in eventfs_release()
  tracing/user_events: Align set_bit() address for all archs
  tracing: relax trace_event_eval_update() execution with cond_resched()
  ring-buffer: Update "shortest_full" in polling

The dcache_dir_open_wrapper() could be called when a dynamic event is
being deleted leaving a dentry with no children. In this case the
dlist->dentries array will never be allocated. This needs to be checked
for in eventfs_release(), otherwise it will trigger a NULL pointer
dereference.

Link: https://lore.kernel.org/linux-trace-kernel/20230930090106.1c3164e9@rorschach.local.home

Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: ef36b4f9 ("eventfs: Remember what dentries were created on dir open")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

All architectures should use a long aligned address passed to set_bit().
User processes can pass either a 32-bit or 64-bit sized value to be
updated when tracing is enabled when on a 64-bit kernel. Both cases are
ensured to be naturally aligned, however, that is not enough. The
address must be long aligned without affecting checks on the value
within the user process which require different adjustments for the bit
for little and big endian CPUs.

Add a compat flag to user_event_enabler that indicates when a 32-bit
value is being used on a 64-bit kernel. Long align addresses and correct
the bit to be used by set_bit() to account for this alignment. Ensure
compat flags are copied during forks and used during deletion clears.

Link: https://lore.kernel.org/linux-trace-kernel/20230925230829.341-2-beaub@linux.microsoft.com
Link: https://lore.kernel.org/linux-trace-kernel/20230914131102.179100-1-cleger@rivosinc.com/

Cc: stable@vger.kernel.org
Fixes: 72357590 ("tracing/user_events: Use remote writes for event enablement")
Reported-by: Clément Léger <cleger@rivosinc.com>
Suggested-by: Clément Léger <cleger@rivosinc.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

When kernel is compiled without preemption, the eval_map_work_func()
(which calls trace_event_eval_update()) will not be preempted up to its
complete execution. This can actually cause a problem since if another
CPU call stop_machine(), the call will have to wait for the
eval_map_work_func() function to finish executing in the workqueue
before being able to be scheduled. This problem was observe on a SMP
system at boot time, when the CPU calling the initcalls executed
clocksource_done_booting() which in the end calls stop_machine(). We
observed a 1 second delay because one CPU was executing
eval_map_work_func() and was not preempted by the stop_machine() task.

Adding a call to cond_resched() in trace_event_eval_update() allows
other tasks to be executed and thus continue working asynchronously
like before without blocking any pending task at boot time.

Link: https://lore.kernel.org/linux-trace-kernel/20230929191637.416931-1-cleger@rivosinc.com

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Tested-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

It was discovered that the ring buffer polling was incorrectly stating
that read would not block, but that's because polling did not take into
account that reads will block if the "buffer-percent" was set. Instead,
the ring buffer polling would say reads would not block if there was any
data in the ring buffer. This was incorrect behavior from a user space
point of view. This was fixed by commit 42fb0a1e by having the polling
code check if the ring buffer had more data than what the user specified
"buffer percent" had.

The problem now is that the polling code did not register itself to the
writer that it wanted to wait for a specific "full" value of the ring
buffer. The result was that the writer would wake the polling waiter
whenever there was a new event. The polling waiter would then wake up, see
that there's not enough data in the ring buffer to notify user space and
then go back to sleep. The next event would wake it up again.

Before the polling fix was added, the code would wake up around 100 times
for a hackbench 30 benchmark. After the "fix", due to the constant waking
of the writer, it would wake up over 11,0000 times! It would never leave
the kernel, so the user space behavior was still "correct", but this
definitely is not the desired effect.

To fix this, have the polling code add what it's waiting for to the
"shortest_full" variable, to tell the writer not to wake it up if the
buffer is not as full as it expects to be.

Note, after this fix, it appears that the waiter is now woken up around 2x
the times it was before (~200). This is a tremendous improvement from the
11,000 times, but I will need to spend some time to see why polling is
more aggressive in its wakeups than the read blocking code.

Link: https://lore.kernel.org/linux-trace-kernel/20230929180113.01c2cae3@rorschach.local.home

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: 42fb0a1e ("tracing/ring-buffer: Have polling block on watermark")
Reported-by: Julia Lawall <julia.lawall@inria.fr>
Tested-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Pull dma-mapping fixes from Christoph Hellwig:

 - fix the narea calculation in swiotlb initialization (Ross Lagerwall)

 - fix the check whether a device has used swiotlb (Petr Tesarik)

* tag 'dma-mapping-6.6-2023-09-30' of git://git.infradead.org/users/hch/dma-mapping:
  swiotlb: fix the check whether a device has used software IO TLB
  swiotlb: use the calculated number of areas

Pull iomap fixes from Darrick Wong:

 - Handle a race between writing and shrinking block devices by
   returning EIO

 - Fix a typo in a comment

* tag 'iomap-6.6-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  iomap: Spelling s/preceeding/preceding/g
  iomap: add a workaround for racy i_size updates on block devices

Pull i2c fixes from Wolfram Sang:
 "Usual business: a driver fix, a DT fix, a minor core fix"

* tag 'i2c-for-6.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: npcm7xx: Fix callback completion ordering
  i2c: mux: Avoid potential false error message in i2c_mux_add_adapter
  dt-bindings: i2c: mxs: Pass ref and 'unevaluatedProperties: false'

Pull ACPI fix from Rafael Wysocki:
 "Fix a possible NULL pointer dereference in the error path of
  acpi_video_bus_add() resulting from recent changes (Dinghao Liu)"

* tag 'acpi-6.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: video: Fix NULL pointer dereference in acpi_video_bus_add()

Pull powerpc fixes from Michael Ellerman:

 - Fix arch_stack_walk_reliable(), used by live patching

 - Fix powerpc selftests to work with run_kselftest.sh

Thanks to Joe Lawrence and Petr Mladek.

* tag 'powerpc-6.6-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  selftests/powerpc: Fix emit_tests to work with run_kselftest.sh
  powerpc/stacktrace: Fix arch_stack_walk_reliable()

Pull nfsd fix from Chuck Lever:

 - Fix NFSv4 READ corner case

* tag 'nfsd-6.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  NFSD: Fix zero NFSv4 READ results when RQ_SPLICE_OK is not set