Patch series "kill task_struct->thread_group".


This patch (of 2):

It could use list_is_singular() but this way it is cheaper.  Plus the
thread_group_leader() check makes it clear that thread_group_empty() can
only return true if p is a group leader.  This was not immediately obvious
before this patch.

task_struct->thread_group no longer has users, it can die.

Link: https://lkml.kernel.org/r/20230826111200.GA22982@redhat.com
Link: https://lkml.kernel.org/r/20230826111406.GA23238@redhat.comSigned-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

This relies on fact that group leader is always the 1st entry in the
signal->thread_head list.

With or without this change, if the lockless next_thread(last_thread)
races with exec it can return the old or the new leader.

We are almost ready to kill task->thread_group, after this change its
only user is thread_group_empty().

Link: https://lkml.kernel.org/r/20230824143201.GB31222@redhat.comSigned-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "introduce __next_thread(), change next_thread()".

After commit dce8f8ed ("document while_each_thread(), change
first_tid() to use for_each_thread()") + this series

1. We have only one lockless user of next_thread(), task_group_seq_get_next().
   I think it should be changed too.

2. We have only one user of task_struct->thread_group, thread_group_empty().
   The next patches will change thread_group_empty() and kill ->thread_group.


This patch (of 2):

next_tid(start) does:

	rcu_read_lock();
	if (pid_alive(start)) {
		pos = next_thread(start);
		if (thread_group_leader(pos))
			pos = NULL;
		else
			get_task_struct(pos);

it should return pos = NULL when next_thread() wraps to the 1st thread
in the thread group, group leader, and the thread_group_leader() check
tries to detect this case.

But this can race with exec. To simplify, suppose we have a main thread
M and a single sub-thread T, next_tid(T) should return NULL.

Now suppose that T execs. If next_tid(T) is called after T changes the
leadership and before it does release_task() which removes the old leader
from list, then next_thread() returns M and thread_group_leader(M) = F.

Lockless use of next_thread() should be avoided. After this change only
task_group_seq_get_next() does this, and I believe it should be changed
as well.

Link: https://lkml.kernel.org/r/20230824143112.GA31208@redhat.com
Link: https://lkml.kernel.org/r/20230824143142.GA31222@redhat.comSigned-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

global bitmap is a cluster allocator,so after we traverse the global
bitmap and finished the fstrim,the trimmed range should be 'trimmed *
clustersize'.otherwise,the trimmed range printed by 'fstrim -v' is not as
expected.

Link: https://lkml.kernel.org/r/20230828051741.204577-1-yuanhengzhang1214@gmail.comSigned-off-by: Yuanheng Zhang <yuanhengzhang1214@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

commit 6f33d587 ("__UNIQUE_ID()")
added a fallback definition of __UNIQUE_ID because gcc 4.2 and older did
not support __COUNTER__.

Also, this commit is effectively a revert of
commit b41c29b0 ("Kbuild: provide a __UNIQUE_ID for clang")
which mentions clang 2.6+ supporting __COUNTER__.

Documentation/process/changes.rst currently lists the minimum supported
version of these compilers as:
- gcc: 5.1
- clang: 11.0.0
It should be safe to say that __COUNTER__ is well supported by this
point.

Link: https://lkml.kernel.org/r/20230831-unique_id-v1-1-28bacd18eb1d@google.comSigned-off-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Michal rarek <mmarek@suse.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Paul Russel <rusty@rustcorp.com.au>
Cc: Tom Rix <trix@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

After move of Documentation/s390 to Documentation/arch/s390

Link: https://lkml.kernel.org/r/20230825013102.1487979-1-costa.shul@redhat.comSigned-off-by: Costa Shulyupin <costa.shul@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Eric DeVolder <eric.devolder@oracle.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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

Pull smb client fix from Steve French:
 "Fix for password freeing potential oops (also for stable)"

* tag '6.6-rc3-smb3-client-fix' of git://git.samba.org/sfrench/cifs-2.6:
  fs/smb/client: Reset password pointer to NULL

Eric reported that handling corresponding crash hotplug event can be
failed easily when many memory hotplug event are notified in a short
period.  They failed because failing to take __kexec_lock.

=======
[   78.714569] Fallback order for Node 0: 0
[   78.714575] Built 1 zonelists, mobility grouping on.  Total pages: 1817886
[   78.717133] Policy zone: Normal
[   78.724423] crash hp: kexec_trylock() failed, elfcorehdr may be inaccurate
[   78.727207] crash hp: kexec_trylock() failed, elfcorehdr may be inaccurate
[   80.056643] PEFILE: Unsigned PE binary
=======

The memory hotplug events are notified very quickly and very many, while
the handling of crash hotplug is much slower relatively.  So the atomic
variable __kexec_lock and kexec_trylock() can't guarantee the
serialization of crash hotplug handling.

Here, add a new mutex lock __crash_hotplug_lock to serialize crash hotplug
handling specifically.  This doesn't impact the usage of __kexec_lock.

Link: https://lkml.kernel.org/r/20230926120905.392903-1-bhe@redhat.com
Fixes: 24726275 ("crash: add generic infrastructure for crash hotplug support")
Signed-off-by: Baoquan He <bhe@redhat.com>
Tested-by: Eric DeVolder <eric.devolder@oracle.com>
Reviewed-by: Eric DeVolder <eric.devolder@oracle.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/mm: fix awk usage in charge_reserved_hugetlb.sh and hugetlb_reparenting_test.sh that may cause error

According to the awk manual, the -e option does not need to be specified
in front of 'program' (unless you need to mix program-file).

The redundant -e option can cause error when users use awk tools other
than gawk (for example, mawk does not support the -e option).

Error Example:
awk: not an option: -e

Link: https://lkml.kernel.org/r/VI1P193MB075228810591AF2FDD7D42C599C3A@VI1P193MB0752.EURP193.PROD.OUTLOOK.COMSigned-off-by: Juntong Deng <juntong.deng@outlook.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

When calling mbind() with MPOL_MF_{MOVE|MOVEALL} | MPOL_MF_STRICT, kernel
should attempt to migrate all existing pages, and return -EIO if there is
misplaced or unmovable page.  Then commit 6f4576e3 ("mempolicy: apply
page table walker on queue_pages_range()") messed up the return value and
didn't break VMA scan early ianymore when MPOL_MF_STRICT alone.  The
return value problem was fixed by commit a7f40cfe ("mm: mempolicy:
make mbind() return -EIO when MPOL_MF_STRICT is specified"), but it broke
the VMA walk early if unmovable page is met, it may cause some pages are
not migrated as expected.

The code should conceptually do:

 if (MPOL_MF_MOVE|MOVEALL)
     scan all vmas
     try to migrate the existing pages
     return success
 else if (MPOL_MF_MOVE* | MPOL_MF_STRICT)
     scan all vmas
     try to migrate the existing pages
     return -EIO if unmovable or migration failed
 else /* MPOL_MF_STRICT alone */
     break early if meets unmovable and don't call mbind_range() at all
 else /* none of those flags */
     check the ranges in test_walk, EFAULT without mbind_range() if discontig.

Fixed the behavior.

Link: https://lkml.kernel.org/r/20230920223242.3425775-1-yang@os.amperecomputing.com
Fixes: a7f40cfe ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified")
Signed-off-by: Yang Shi <yang@os.amperecomputing.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>	[4.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

When CONFIG_DAMON_VADDR_KUNIT_TEST=y and making CONFIG_DEBUG_KMEMLEAK=y
and CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN=y, the below memory leak is detected.

Since commit 9f86d624 ("mm/damon/vaddr-test: remove unnecessary
variables"), the damon_destroy_ctx() is removed, but still call
damon_new_target() and damon_new_region(), the damon_region which is
allocated by kmem_cache_alloc() in damon_new_region() and the damon_target
which is allocated by kmalloc in damon_new_target() are not freed.  And
the damon_region which is allocated in damon_new_region() in
damon_set_regions() is also not freed.

So use damon_destroy_target to free all the damon_regions and damon_target.

    unreferenced object 0xffff888107c9a940 (size 64):
      comm "kunit_try_catch", pid 1069, jiffies 4294670592 (age 732.761s)
      hex dump (first 32 bytes):
        00 00 00 00 00 00 00 00 06 00 00 00 6b 6b 6b 6b  ............kkkk
        60 c7 9c 07 81 88 ff ff f8 cb 9c 07 81 88 ff ff  `...............
      backtrace:
        [<ffffffff817e0167>] kmalloc_trace+0x27/0xa0
        [<ffffffff819c11cf>] damon_new_target+0x3f/0x1b0
        [<ffffffff819c7d55>] damon_do_test_apply_three_regions.constprop.0+0x95/0x3e0
        [<ffffffff819c82be>] damon_test_apply_three_regions1+0x21e/0x260
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20
    unreferenced object 0xffff8881079cc740 (size 56):
      comm "kunit_try_catch", pid 1069, jiffies 4294670592 (age 732.761s)
      hex dump (first 32 bytes):
        05 00 00 00 00 00 00 00 14 00 00 00 00 00 00 00  ................
        6b 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 6b 6b 6b 6b  kkkkkkkk....kkkk
      backtrace:
        [<ffffffff819bc492>] damon_new_region+0x22/0x1c0
        [<ffffffff819c7d91>] damon_do_test_apply_three_regions.constprop.0+0xd1/0x3e0
        [<ffffffff819c82be>] damon_test_apply_three_regions1+0x21e/0x260
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20
    unreferenced object 0xffff888107c9ac40 (size 64):
      comm "kunit_try_catch", pid 1071, jiffies 4294670595 (age 732.843s)
      hex dump (first 32 bytes):
        00 00 00 00 00 00 00 00 06 00 00 00 6b 6b 6b 6b  ............kkkk
        a0 cc 9c 07 81 88 ff ff 78 a1 76 07 81 88 ff ff  ........x.v.....
      backtrace:
        [<ffffffff817e0167>] kmalloc_trace+0x27/0xa0
        [<ffffffff819c11cf>] damon_new_target+0x3f/0x1b0
        [<ffffffff819c7d55>] damon_do_test_apply_three_regions.constprop.0+0x95/0x3e0
        [<ffffffff819c851e>] damon_test_apply_three_regions2+0x21e/0x260
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20
    unreferenced object 0xffff8881079ccc80 (size 56):
      comm "kunit_try_catch", pid 1071, jiffies 4294670595 (age 732.843s)
      hex dump (first 32 bytes):
        05 00 00 00 00 00 00 00 14 00 00 00 00 00 00 00  ................
        6b 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 6b 6b 6b 6b  kkkkkkkk....kkkk
      backtrace:
        [<ffffffff819bc492>] damon_new_region+0x22/0x1c0
        [<ffffffff819c7d91>] damon_do_test_apply_three_regions.constprop.0+0xd1/0x3e0
        [<ffffffff819c851e>] damon_test_apply_three_regions2+0x21e/0x260
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20
    unreferenced object 0xffff888107c9af40 (size 64):
      comm "kunit_try_catch", pid 1073, jiffies 4294670597 (age 733.011s)
      hex dump (first 32 bytes):
        00 00 00 00 00 00 00 00 06 00 00 00 6b 6b 6b 6b  ............kkkk
        20 a2 76 07 81 88 ff ff b8 a6 76 07 81 88 ff ff   .v.......v.....
      backtrace:
        [<ffffffff817e0167>] kmalloc_trace+0x27/0xa0
        [<ffffffff819c11cf>] damon_new_target+0x3f/0x1b0
        [<ffffffff819c7d55>] damon_do_test_apply_three_regions.constprop.0+0x95/0x3e0
        [<ffffffff819c877e>] damon_test_apply_three_regions3+0x21e/0x260
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20
    unreferenced object 0xffff88810776a200 (size 56):
      comm "kunit_try_catch", pid 1073, jiffies 4294670597 (age 733.011s)
      hex dump (first 32 bytes):
        05 00 00 00 00 00 00 00 14 00 00 00 00 00 00 00  ................
        6b 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 6b 6b 6b 6b  kkkkkkkk....kkkk
      backtrace:
        [<ffffffff819bc492>] damon_new_region+0x22/0x1c0
        [<ffffffff819c7d91>] damon_do_test_apply_three_regions.constprop.0+0xd1/0x3e0
        [<ffffffff819c877e>] damon_test_apply_three_regions3+0x21e/0x260
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20
    unreferenced object 0xffff88810776a740 (size 56):
      comm "kunit_try_catch", pid 1073, jiffies 4294670597 (age 733.025s)
      hex dump (first 32 bytes):
        3d 00 00 00 00 00 00 00 3f 00 00 00 00 00 00 00  =.......?.......
        6b 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 6b 6b 6b 6b  kkkkkkkk....kkkk
      backtrace:
        [<ffffffff819bc492>] damon_new_region+0x22/0x1c0
        [<ffffffff819bfcc2>] damon_set_regions+0x4c2/0x8e0
        [<ffffffff819c7dbb>] damon_do_test_apply_three_regions.constprop.0+0xfb/0x3e0
        [<ffffffff819c877e>] damon_test_apply_three_regions3+0x21e/0x260
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20
    unreferenced object 0xffff888108038240 (size 64):
      comm "kunit_try_catch", pid 1075, jiffies 4294670600 (age 733.022s)
      hex dump (first 32 bytes):
        00 00 00 00 00 00 00 00 03 00 00 00 6b 6b 6b 6b  ............kkkk
        48 ad 76 07 81 88 ff ff 98 ae 76 07 81 88 ff ff  H.v.......v.....
      backtrace:
        [<ffffffff817e0167>] kmalloc_trace+0x27/0xa0
        [<ffffffff819c11cf>] damon_new_target+0x3f/0x1b0
        [<ffffffff819c7d55>] damon_do_test_apply_three_regions.constprop.0+0x95/0x3e0
        [<ffffffff819c898d>] damon_test_apply_three_regions4+0x1cd/0x210
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20
    unreferenced object 0xffff88810776ad28 (size 56):
      comm "kunit_try_catch", pid 1075, jiffies 4294670600 (age 733.022s)
      hex dump (first 32 bytes):
        05 00 00 00 00 00 00 00 07 00 00 00 00 00 00 00  ................
        6b 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 6b 6b 6b 6b  kkkkkkkk....kkkk
      backtrace:
        [<ffffffff819bc492>] damon_new_region+0x22/0x1c0
        [<ffffffff819bfcc2>] damon_set_regions+0x4c2/0x8e0
        [<ffffffff819c7dbb>] damon_do_test_apply_three_regions.constprop.0+0xfb/0x3e0
        [<ffffffff819c898d>] damon_test_apply_three_regions4+0x1cd/0x210
        [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90
        [<ffffffff81237cf6>] kthread+0x2b6/0x380
        [<ffffffff81097add>] ret_from_fork+0x2d/0x70
        [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20

Link: https://lkml.kernel.org/r/20230925072100.3725620-1-ruanjinjie@huawei.com
Fixes: 9f86d624 ("mm/damon/vaddr-test: remove unnecessary variables")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

This reverts commits 86327e8e ("memcg: drop kmem.limit_in_bytes") and
partially reverts 58056f77 ("memcg, kmem: further deprecate
kmem.limit_in_bytes") which have incrementally removed support for the
kernel memory accounting hard limit.  Unfortunately it has turned out that
there is still userspace depending on the existence of
memory.kmem.limit_in_bytes [1].  The underlying functionality is not
really required but the non-existent file just confuses the userspace
which fails in the result.  The patch to fix this on the userspace side
has been submitted but it is hard to predict how it will propagate through
the maze of 3rd party consumers of the software.

Now, reverting alone 86327e8e is not an option because there is
another set of userspace which cannot cope with ENOTSUPP returned when
writing to the file.  Therefore we have to go and revisit 58056f77 as
well.  There are two ways to go ahead.  Either we give up on the
deprecation and fully revert 58056f77 as well or we can keep
kmem.limit_in_bytes but make the write a noop and warn about the fact. 
This should work for both known breaking workloads which depend on the
existence but do not depend on the hard limit enforcement.

Note to backporters to stable trees.  a8c49af3 ("memcg: add per-memcg
total kernel memory stat") introduced in 4.18 has added memcg_account_kmem
so the accounting is not done by obj_cgroup_charge_pages directly for v1
anymore.  Prior kernels need to add it explicitly (thanks to Johannes for
pointing this out).

[akpm@linux-foundation.org: fix build - remove unused local]
Link: http://lkml.kernel.org/r/20230920081101.GA12096@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net [1]
Link: https://lkml.kernel.org/r/ZRE5VJozPZt9bRPy@dhcp22.suse.cz
Fixes: 86327e8e ("memcg: drop kmem.limit_in_bytes")
Fixes: 58056f77 ("memcg, kmem: further deprecate kmem.limit_in_bytes")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

While stress-testing zswap a memory corruption was happening when writing
back pages.  __frontswap_store used to check for duplicate entries before
attempting to store a page in zswap, this was because if the store fails
the old entry isn't removed from the tree.  This change removes duplicate
entries in zswap_store before the actual attempt.

[cerasuolodomenico@gmail.com: add a warning and a comment, per Johannes]
  Link: https://lkml.kernel.org/r/20230925130002.1929369-1-cerasuolodomenico@gmail.com
Link: https://lkml.kernel.org/r/20230922172211.1704917-1-cerasuolodomenico@gmail.com
Fixes: 42c06a0e ("mm: kill frontswap")
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

When called with a swap entry that does not embed a PFN (e.g. 
PTE_MARKER_POISONED or PTE_MARKER_UFFD_WP), the previous implementation of
set_huge_pte_at() would either cause a BUG() to fire (if CONFIG_DEBUG_VM
is enabled) or cause a dereference of an invalid address and subsequent
panic.

arm64's huge pte implementation supports multiple huge page sizes, some of
which are implemented in the page table with multiple contiguous entries. 
So set_huge_pte_at() needs to work out how big the logical pte is, so that
it can also work out how many physical ptes (or pmds) need to be written. 
It previously did this by grabbing the folio out of the pte and querying
its size.

However, there are cases when the pte being set is actually a swap entry. 
But this also used to work fine, because for huge ptes, we only ever saw
migration entries and hwpoison entries.  And both of these types of swap
entries have a PFN embedded, so the code would grab that and everything
still worked out.

But over time, more calls to set_huge_pte_at() have been added that set
swap entry types that do not embed a PFN.  And this causes the code to go
bang.  The triggering case is for the uffd poison test, commit
99aa7721 ("selftests/mm: add uffd unit test for UFFDIO_POISON"), which
causes a PTE_MARKER_POISONED swap entry to be set, coutesey of commit
8a13897f ("mm: userfaultfd: support UFFDIO_POISON for hugetlbfs") -
added in v6.5-rc7.  Although review shows that there are other call sites
that set PTE_MARKER_UFFD_WP (which also has no PFN), these don't trigger
on arm64 because arm64 doesn't support UFFD WP.

Arguably, the root cause is really due to commit 18f39629 ("mm:
hugetlb: kill set_huge_swap_pte_at()"), which aimed to simplify the
interface to the core code by removing set_huge_swap_pte_at() (which took
a page size parameter) and replacing it with calls to set_huge_pte_at()
where the size was inferred from the folio, as descibed above.  While that
commit didn't break anything at the time, it did break the interface
because it couldn't handle swap entries without PFNs.  And since then new
callers have come along which rely on this working.  But given the
brokeness is only observable after commit 8a13897f ("mm: userfaultfd:
support UFFDIO_POISON for hugetlbfs"), that one gets the Fixes tag.

Now that we have modified the set_huge_pte_at() interface to pass the huge
page size in the previous patch, we can trivially fix this issue.

Link: https://lkml.kernel.org/r/20230922115804.2043771-3-ryan.roberts@arm.com
Fixes: 8a13897f ("mm: userfaultfd: support UFFDIO_POISON for hugetlbfs")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <stable@vger.kernel.org>	[6.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "Fix set_huge_pte_at() panic on arm64", v2.

This series fixes a bug in arm64's implementation of set_huge_pte_at(),
which can result in an unprivileged user causing a kernel panic.  The
problem was triggered when running the new uffd poison mm selftest for
HUGETLB memory.  This test (and the uffd poison feature) was merged for
v6.5-rc7.

Ideally, I'd like to get this fix in for v6.6 and I've cc'ed stable
(correctly this time) to get it backported to v6.5, where the issue first
showed up.


Description of Bug
==================

arm64's huge pte implementation supports multiple huge page sizes, some of
which are implemented in the page table with multiple contiguous entries. 
So set_huge_pte_at() needs to work out how big the logical pte is, so that
it can also work out how many physical ptes (or pmds) need to be written. 
It previously did this by grabbing the folio out of the pte and querying
its size.

However, there are cases when the pte being set is actually a swap entry. 
But this also used to work fine, because for huge ptes, we only ever saw
migration entries and hwpoison entries.  And both of these types of swap
entries have a PFN embedded, so the code would grab that and everything
still worked out.

But over time, more calls to set_huge_pte_at() have been added that set
swap entry types that do not embed a PFN.  And this causes the code to go
bang.  The triggering case is for the uffd poison test, commit
99aa7721 ("selftests/mm: add uffd unit test for UFFDIO_POISON"), which
causes a PTE_MARKER_POISONED swap entry to be set, coutesey of commit
8a13897f ("mm: userfaultfd: support UFFDIO_POISON for hugetlbfs") -
added in v6.5-rc7.  Although review shows that there are other call sites
that set PTE_MARKER_UFFD_WP (which also has no PFN), these don't trigger
on arm64 because arm64 doesn't support UFFD WP.

If CONFIG_DEBUG_VM is enabled, we do at least get a BUG(), but otherwise,
it will dereference a bad pointer in page_folio():

    static inline struct folio *hugetlb_swap_entry_to_folio(swp_entry_t entry)
    {
        VM_BUG_ON(!is_migration_entry(entry) && !is_hwpoison_entry(entry));

        return page_folio(pfn_to_page(swp_offset_pfn(entry)));
    }


Fix
===

The simplest fix would have been to revert the dodgy cleanup commit
18f39629 ("mm: hugetlb: kill set_huge_swap_pte_at()"), but since
things have moved on, this would have required an audit of all the new
set_huge_pte_at() call sites to see if they should be converted to
set_huge_swap_pte_at().  As per the original intent of the change, it
would also leave us open to future bugs when people invariably get it
wrong and call the wrong helper.

So instead, I've added a huge page size parameter to set_huge_pte_at(). 
This means that the arm64 code has the size in all cases.  It's a bigger
change, due to needing to touch the arches that implement the function,
but it is entirely mechanical, so in my view, low risk.

I've compile-tested all touched arches; arm64, parisc, powerpc, riscv,
s390, sparc (and additionally x86_64).  I've additionally booted and run
mm selftests against arm64, where I observe the uffd poison test is fixed,
and there are no other regressions.


This patch (of 2):

In order to fix a bug, arm64 needs to be told the size of the huge page
for which the pte is being set in set_huge_pte_at().  Provide for this by
adding an `unsigned long sz` parameter to the function.  This follows the
same pattern as huge_pte_clear().

This commit makes the required interface modifications to the core mm as
well as all arches that implement this function (arm64, parisc, powerpc,
riscv, s390, sparc).  The actual arm64 bug will be fixed in a separate
commit.

No behavioral changes intended.

Link: https://lkml.kernel.org/r/20230922115804.2043771-1-ryan.roberts@arm.com
Link: https://lkml.kernel.org/r/20230922115804.2043771-2-ryan.roberts@arm.com
Fixes: 8a13897f ("mm: userfaultfd: support UFFDIO_POISON for hugetlbfs")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>	[powerpc 8xx]
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>	[vmalloc change]
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <stable@vger.kernel.org>	[6.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>