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  1. 05 Sep, 2024 2 commits
  3. 04 Sep, 2024 11 commits
  5. 03 Sep, 2024 4 commits
    • Linus Torvalds's avatar
      Merge tag 'fuse-fixes-6.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse · 88fac175
      Linus Torvalds authored 
      Pull fuse fixes from Miklos Szeredi:

 - Fix EIO if splice and page stealing are enabled on the fuse device

 - Disable problematic combination of passthrough and writeback-cache

 - Other bug fixes found by code review

* tag 'fuse-fixes-6.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: disable the combination of passthrough and writeback cache
  fuse: update stats for pages in dropped aux writeback list
  fuse: clear PG_uptodate when using a stolen page
  fuse: fix memory leak in fuse_create_open
  fuse: check aborted connection before adding requests to pending list for resending
  fuse: use unsigned type for getxattr/listxattr size truncation
      88fac175
    • Filipe Manana's avatar
      btrfs: fix race between direct IO write and fsync when using same fd · cd9253c2
      Filipe Manana authored 
      If we have 2 threads that are using the same file descriptor and one of
them is doing direct IO writes while the other is doing fsync, we have a
race where we can end up either:

1) Attempt a fsync without holding the inode's lock, triggering an
   assertion failures when assertions are enabled;

2) Do an invalid memory access from the fsync task because the file private
   points to memory allocated on stack by the direct IO task and it may be
   used by the fsync task after the stack was destroyed.

The race happens like this:

1) A user space program opens a file descriptor with O_DIRECT;

2) The program spawns 2 threads using libpthread for example;

3) One of the threads uses the file descriptor to do direct IO writes,
   while the other calls fsync using the same file descriptor.

4) Call task A the thread doing direct IO writes and task B the thread
   doing fsyncs;

5) Task A does a direct IO write, and at btrfs_direct_write() sets the
   file's private to an on stack allocated private with the member
   'fsync_skip_inode_lock' set to true;

6) Task B enters btrfs_sync_file() and sees that there's a private
   structure associated to the file which has 'fsync_skip_inode_lock' set
   to true, so it skips locking the inode's VFS lock;

7) Task A completes the direct IO write, and resets the file's private to
   NULL since it had no prior private and our private was stack allocated.
   Then it unlocks the inode's VFS lock;

8) Task B enters btrfs_get_ordered_extents_for_logging(), then the
   assertion that checks the inode's VFS lock is held fails, since task B
   never locked it and task A has already unlocked it.

The stack trace produced is the following:

   assertion failed: inode_is_locked(&inode->vfs_inode), in fs/btrfs/ordered-data.c:983
   ------------[ cut here ]------------
   kernel BUG at fs/btrfs/ordered-data.c:983!
   Oops: invalid opcode: 0000 [#1] PREEMPT SMP PTI
   CPU: 9 PID: 5072 Comm: worker Tainted: G     U     OE      6.10.5-1-default #1 openSUSE Tumbleweed 69f48d427608e1c09e60ea24c6c55e2ca1b049e8
   Hardware name: Acer Predator PH315-52/Covini_CFS, BIOS V1.12 07/28/2020
   RIP: 0010:btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs]
   Code: 50 d6 86 c0 e8 (...)
   RSP: 0018:ffff9e4a03dcfc78 EFLAGS: 00010246
   RAX: 0000000000000054 RBX: ffff9078a9868e98 RCX: 0000000000000000
   RDX: 0000000000000000 RSI: ffff907dce4a7800 RDI: ffff907dce4a7800
   RBP: ffff907805518800 R08: 0000000000000000 R09: ffff9e4a03dcfb38
   R10: ffff9e4a03dcfb30 R11: 0000000000000003 R12: ffff907684ae7800
   R13: 0000000000000001 R14: ffff90774646b600 R15: 0000000000000000
   FS:  00007f04b96006c0(0000) GS:ffff907dce480000(0000) knlGS:0000000000000000
   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
   CR2: 00007f32acbfc000 CR3: 00000001fd4fa005 CR4: 00000000003726f0
   Call Trace:
    <TASK>
    ? __die_body.cold+0x14/0x24
    ? die+0x2e/0x50
    ? do_trap+0xca/0x110
    ? do_error_trap+0x6a/0x90
    ? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
    ? exc_invalid_op+0x50/0x70
    ? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
    ? asm_exc_invalid_op+0x1a/0x20
    ? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
    ? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
    btrfs_sync_file+0x21a/0x4d0 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
    ? __seccomp_filter+0x31d/0x4f0
    __x64_sys_fdatasync+0x4f/0x90
    do_syscall_64+0x82/0x160
    ? do_futex+0xcb/0x190
    ? __x64_sys_futex+0x10e/0x1d0
    ? switch_fpu_return+0x4f/0xd0
    ? syscall_exit_to_user_mode+0x72/0x220
    ? do_syscall_64+0x8e/0x160
    ? syscall_exit_to_user_mode+0x72/0x220
    ? do_syscall_64+0x8e/0x160
    ? syscall_exit_to_user_mode+0x72/0x220
    ? do_syscall_64+0x8e/0x160
    ? syscall_exit_to_user_mode+0x72/0x220
    ? do_syscall_64+0x8e/0x160
    entry_SYSCALL_64_after_hwframe+0x76/0x7e

Another problem here is if task B grabs the private pointer and then uses
it after task A has finished, since the private was allocated in the stack
of task A, it results in some invalid memory access with a hard to predict
result.

This issue, triggering the assertion, was observed with QEMU workloads by
two users in the Link tags below.

Fix this by not relying on a file's private to pass information to fsync
that it should skip locking the inode and instead pass this information
through a special value stored in current->journal_info. This is safe
because in the relevant section of the direct IO write path we are not
holding a transaction handle, so current->journal_info is NULL.

The following C program triggers the issue:

   $ cat repro.c
   /* Get the O_DIRECT definition. */
   #ifndef _GNU_SOURCE
   #define _GNU_SOURCE
   #endif

   #include <stdio.h>
   #include <stdlib.h>
   #include <unistd.h>
   #include <stdint.h>
   #include <fcntl.h>
   #include <errno.h>
   #include <string.h>
   #include <pthread.h>

   static int fd;

   static ssize_t do_write(int fd, const void *buf, size_t count, off_t offset)
   {
       while (count > 0) {
           ssize_t ret;

           ret = pwrite(fd, buf, count, offset);
           if (ret < 0) {
               if (errno == EINTR)
                   continue;
               return ret;
           }
           count -= ret;
           buf += ret;
       }
       return 0;
   }

   static void *fsync_loop(void *arg)
   {
       while (1) {
           int ret;

           ret = fsync(fd);
           if (ret != 0) {
               perror("Fsync failed");
               exit(6);
           }
       }
   }

   int main(int argc, char *argv[])
   {
       long pagesize;
       void *write_buf;
       pthread_t fsyncer;
       int ret;

       if (argc != 2) {
           fprintf(stderr, "Use: %s <file path>\n", argv[0]);
           return 1;
       }

       fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC | O_DIRECT, 0666);
       if (fd == -1) {
           perror("Failed to open/create file");
           return 1;
       }

       pagesize = sysconf(_SC_PAGE_SIZE);
       if (pagesize == -1) {
           perror("Failed to get page size");
           return 2;
       }

       ret = posix_memalign(&write_buf, pagesize, pagesize);
       if (ret) {
           perror("Failed to allocate buffer");
           return 3;
       }

       ret = pthread_create(&fsyncer, NULL, fsync_loop, NULL);
       if (ret != 0) {
           fprintf(stderr, "Failed to create writer thread: %d\n", ret);
           return 4;
       }

       while (1) {
           ret = do_write(fd, write_buf, pagesize, 0);
           if (ret != 0) {
               perror("Write failed");
               exit(5);
           }
       }

       return 0;
   }

   $ mkfs.btrfs -f /dev/sdi
   $ mount /dev/sdi /mnt/sdi
   $ timeout 10 ./repro /mnt/sdi/foo

Usually the race is triggered within less than 1 second. A test case for
fstests will follow soon.
Reported-by: default avatarPaulo Dias <paulo.miguel.dias@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219187Reported-by: default avatarAndreas Jahn <jahn-andi@web.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219199
Reported-by: syzbot+4704b3cc972bd76024f1@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/00000000000044ff540620d7dee2@google.com/
Fixes: 939b656b ("btrfs: fix corruption after buffer fault in during direct IO append write")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
      cd9253c2
    • Luke D. Jones's avatar
      platform/x86/amd: pmf: Make ASUS GA403 quirk generic · d34af755
      Luke D. Jones authored 
      The original quirk should match to GA403U so that the full
range of GA403U models can benefit.
Signed-off-by: default avatarLuke D. Jones <luke@ljones.dev>
Link: https://lore.kernel.org/r/20240831003905.1060977-1-luke@ljones.devReviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
      d34af755
    • Helge Deller's avatar
      parisc: Delay write-protection until mark_rodata_ro() call · 213aa670
      Helge Deller authored 
      Do not write-protect the kernel read-only and __ro_after_init sections
earlier than before mark_rodata_ro() is called.  This fixes a boot issue on
parisc which is triggered by commit 91a1d97e ("jump_label,module: Don't
alloc static_key_mod for __ro_after_init keys"). That commit may modify
static key contents in the __ro_after_init section at bootup, so this
section needs to be writable at least until mark_rodata_ro() is called.
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
Reported-by: default avatarmatoro <matoro_mailinglist_kernel@matoro.tk>
Reported-by: default avatarChristoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Tested-by: default avatarChristoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Link: https://lore.kernel.org/linux-parisc/096cad5aada514255cd7b0b9dbafc768@matoro.tk/#r
Fixes: 91a1d97e ("jump_label,module: Don't alloc static_key_mod for __ro_after_init keys")
Cc: stable@vger.kernel.org # v6.10+
      213aa670
  7. 02 Sep, 2024 23 commits
    • Naohiro Aota's avatar
      btrfs: zoned: handle broken write pointer on zones · b1934cd6
      Naohiro Aota authored 
      Btrfs rejects to mount a FS if it finds a block group with a broken write
pointer (e.g, unequal write pointers on two zones of RAID1 block group).
Since such case can happen easily with a power-loss or crash of a system,
we need to handle the case more gently.

Handle such block group by making it unallocatable, so that there will be
no writes into it. That can be done by setting the allocation pointer at
the end of allocating region (= block_group->zone_capacity). Then, existing
code handle zone_unusable properly.

Having proper zone_capacity is necessary for the change. So, set it as fast
as possible.

We cannot handle RAID0 and RAID10 case like this. But, they are anyway
unable to read because of a missing stripe.

Fixes: 265f7237 ("btrfs: zoned: allow DUP on meta-data block groups")
Fixes: 568220fa ("btrfs: zoned: support RAID0/1/10 on top of raid stripe tree")
CC: stable@vger.kernel.org # 6.1+
Reported-by: default avatarHAN Yuwei <hrx@bupt.moe>
Cc: Xuefer <xuefer@gmail.com>
Signed-off-by: default avatarNaohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
      b1934cd6
    • Arnaldo Carvalho de Melo's avatar
      perf daemon: Fix the build on more 32-bit architectures · e162cb25
      Arnaldo Carvalho de Melo authored 
      FYI: I'm carrying this on perf-tools-next.

The previous attempt fixed the build on debian:experimental-x-mipsel,
but when building on a larger set of containers I noticed it broke the
build on some other 32-bit architectures such as:

  42     7.87 ubuntu:18.04-x-arm            : FAIL gcc version 7.5.0 (Ubuntu/Linaro 7.5.0-3ubuntu1~18.04)
    builtin-daemon.c: In function 'cmd_session_list':
    builtin-daemon.c:692:16: error: format '%llu' expects argument of type 'long long unsigned int', but argument 4 has type 'long int' [-Werror=format=]
       fprintf(out, "%c%" PRIu64,
                    ^~~~~
    builtin-daemon.c:694:13:
        csv_sep, (curr - daemon->start) / 60);
                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In file included from builtin-daemon.c:3:0:
    /usr/arm-linux-gnueabihf/include/inttypes.h:105:34: note: format string is defined here
     # define PRIu64  __PRI64_PREFIX "u"

So lets cast that time_t (32-bit/64-bit) to uint64_t to make sure it
builds everywhere.

Fixes: 4bbe6002 ("perf daemon: Fix the build on 32-bit architectures")
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/r/ZsPmldtJ0D9Cua9_@x1Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      e162cb25
    • Xu Yang's avatar
      perf python: include "util/sample.h" · aee1d559
      Xu Yang authored 
      The 32-bit arm build system will complain:

tools/perf/util/python.c:75:28: error: field ‘sample’ has incomplete type
   75 |         struct perf_sample sample;

However, arm64 build system doesn't complain this.

The root cause is arm64 define "HAVE_KVM_STAT_SUPPORT := 1" in
tools/perf/arch/arm64/Makefile, but arm arch doesn't define this.
This will lead to kvm-stat.h include other header files on arm64 build
system, especially "util/sample.h" for util/python.c.

This will try to directly include "util/sample.h" for "util/python.c" to
avoid such build issue on arm platform.
Signed-off-by: default avatarXu Yang <xu.yang_2@nxp.com>
Cc: imx@lists.linux.dev
Link: https://lore.kernel.org/r/20240819023403.201324-1-xu.yang_2@nxp.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      aee1d559
    • Namhyung Kim's avatar
      perf lock contention: Fix spinlock and rwlock accounting · 287bd5cf
      Namhyung Kim authored 
      The spinlock and rwlock use a single-element per-cpu array to track
current locks due to performance reason.  But this means the key is
always available and it cannot simply account lock stats in the array
because some of them are invalid.

In fact, the contention_end() program in the BPF invalidates the entry
by setting the 'lock' value to 0 instead of deleting the entry for the
hashmap.  So it should skip entries with the lock value of 0 in the
account_end_timestamp().

Otherwise, it'd have spurious high contention on an idle machine:

  $ sudo perf lock con -ab -Y spinlock sleep 3
   contended   total wait     max wait     avg wait         type   caller

           8      4.72 s       1.84 s     590.46 ms     spinlock   rcu_core+0xc7
           8      1.87 s       1.87 s     233.48 ms     spinlock   process_one_work+0x1b5
           2      1.87 s       1.87 s     933.92 ms     spinlock   worker_thread+0x1a2
           3      1.81 s       1.81 s     603.93 ms     spinlock   tmigr_update_events+0x13c
           2      1.72 s       1.72 s     861.98 ms     spinlock   tick_do_update_jiffies64+0x25
           6     42.48 us     13.02 us      7.08 us     spinlock   futex_q_lock+0x2a
           1     13.03 us     13.03 us     13.03 us     spinlock   futex_wake+0xce
           1     11.61 us     11.61 us     11.61 us     spinlock   rcu_core+0xc7

I don't believe it has contention on a spinlock longer than 1 second.
After this change, it only reports some small contentions.

  $ sudo perf lock con -ab -Y spinlock sleep 3
   contended   total wait     max wait     avg wait         type   caller

           4    133.51 us     43.29 us     33.38 us     spinlock   tick_do_update_jiffies64+0x25
           4     69.06 us     31.82 us     17.27 us     spinlock   process_one_work+0x1b5
           2     50.66 us     25.77 us     25.33 us     spinlock   rcu_core+0xc7
           1     28.45 us     28.45 us     28.45 us     spinlock   rcu_core+0xc7
           1     24.77 us     24.77 us     24.77 us     spinlock   tmigr_update_events+0x13c
           1     23.34 us     23.34 us     23.34 us     spinlock   raw_spin_rq_lock_nested+0x15

Fixes: b5711042 ("perf lock contention: Use per-cpu array map for spinlocks")
Reported-by: default avatarXi Wang <xii@google.com>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20240828052953.1445862-1-namhyung@kernel.orgSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      287bd5cf
    • Veronika Molnarova's avatar
      perf test pmu: Set uninitialized PMU alias to null · 1c7fb536
      Veronika Molnarova authored 
      Commit 3e0bf9fd ("perf pmu: Restore full PMU name wildcard
support") adds a test case "PMU cmdline match" that covers PMU name
wildcard support provided by function perf_pmu__match(). The test works
with a wide range of supported combinations of PMU name matching but
omits the case that if the perf_pmu__match() cannot match the PMU name
to the wildcard, it tries to match its alias. However, this variable is
not set up, causing the test case to fail when run with subprocesses or
to segfault if run as a single process.

  ./perf test -vv 9
    9: Sysfs PMU tests                                                 :
    9.1: Parsing with PMU format directory                             : Ok
    9.2: Parsing with PMU event                                        : Ok
    9.3: PMU event names                                               : Ok
    9.4: PMU name combining                                            : Ok
    9.5: PMU name comparison                                           : Ok
    9.6: PMU cmdline match                                             : FAILED!

  ./perf test -F 9
    9.1: Parsing with PMU format directory                             : Ok
    9.2: Parsing with PMU event                                        : Ok
    9.3: PMU event names                                               : Ok
    9.4: PMU name combining                                            : Ok
    9.5: PMU name comparison                                           : Ok
  Segmentation fault (core dumped)

Initialize the PMU alias to null for all tests of perf_pmu__match()
as this functionality is not being tested and the alias matching works
exactly the same as the matching of the PMU name.

  ./perf test -F 9
    9.1: Parsing with PMU format directory                             : Ok
    9.2: Parsing with PMU event                                        : Ok
    9.3: PMU event names                                               : Ok
    9.4: PMU name combining                                            : Ok
    9.5: PMU name comparison                                           : Ok
    9.6: PMU cmdline match                                             : Ok

Fixes: 3e0bf9fd ("perf pmu: Restore full PMU name wildcard support")
Signed-off-by: default avatarVeronika Molnarova <vmolnaro@redhat.com>
Cc: james.clark@arm.com
Cc: mpetlan@redhat.com
Cc: rstoyano@redhat.com
Link: https://lore.kernel.org/r/20240808103749.9356-1-vmolnaro@redhat.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
      1c7fb536
    • Fedor Pchelkin's avatar
      btrfs: qgroup: don't use extent changeset when not needed · c346c629
      Fedor Pchelkin authored 
      The local extent changeset is passed to clear_record_extent_bits() where
it may have some additional memory dynamically allocated for ulist. When
qgroup is disabled, the memory is leaked because in this case the
changeset is not released upon __btrfs_qgroup_release_data() return.

Since the recorded contents of the changeset are not used thereafter, just
don't pass it.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Reported-by: syzbot+81670362c283f3dd889c@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/000000000000aa8c0c060ade165e@google.com
Fixes: af0e2aab ("btrfs: qgroup: flush reservations during quota disable")
CC: stable@vger.kernel.org # 6.10+
Reviewed-by: default avatarBoris Burkov <boris@bur.io>
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarFedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
      c346c629
    • Armin Wolf's avatar
      hwmon: (hp-wmi-sensors) Check if WMI event data exists · a54da9df
      Armin Wolf authored 
      The BIOS can choose to return no event data in response to a
WMI event, so the ACPI object passed to the WMI notify handler
can be NULL.

Check for such a situation and ignore the event in such a case.

Fixes: 23902f98 ("hwmon: add HP WMI Sensors driver")
Signed-off-by: default avatarArmin Wolf <W_Armin@gmx.de>
Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Message-ID: <20240901031055.3030-2-W_Armin@gmx.de>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
      a54da9df
    • Linus Torvalds's avatar
      Merge tag 'ata-6.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/libata/linux · 67784a74
      Linus Torvalds authored 
      Pull ata fix from Damien Le Moal:

 - Fix a potential memory leak in the ata host initialization code (from
   Zheng)

* tag 'ata-6.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/libata/linux:
  ata: libata: Fix memory leak for error path in ata_host_alloc()
      67784a74
    • Suren Baghdasaryan's avatar
      alloc_tag: fix allocation tag reporting when CONFIG_MODULES=n · 052a45c1
      Suren Baghdasaryan authored 
      codetag_module_init() is used to initialize sections containing allocation
tags.  This function is used to initialize module sections as well as core
kernel sections, in which case the module parameter is set to NULL.  This
function has to be called even when CONFIG_MODULES=n to initialize core
kernel allocation tag sections.  When CONFIG_MODULES=n, this function is a
NOP, which is wrong.  This leads to /proc/allocinfo reported as empty. 
Fix this by making it independent of CONFIG_MODULES.

Link: https://lkml.kernel.org/r/20240828231536.1770519-1-surenb@google.com
Fixes: 916cc516 ("lib: code tagging framework")
Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>	[6.10+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      052a45c1
    • Adrian Huang's avatar
      mm: vmalloc: optimize vmap_lazy_nr arithmetic when purging each vmap_area · 409faf8c
      Adrian Huang authored 
      When running the vmalloc stress on a 448-core system, observe the average
latency of purge_vmap_node() is about 2 seconds by using the eBPF/bcc
'funclatency.py' tool [1].

  # /your-git-repo/bcc/tools/funclatency.py -u purge_vmap_node & pid1=$! && sleep 8 && modprobe test_vmalloc nr_threads=$(nproc) run_test_mask=0x7; kill -SIGINT $pid1

     usecs             : count    distribution
        0 -> 1         : 0       |                                        |
        2 -> 3         : 29      |                                        |
        4 -> 7         : 19      |                                        |
        8 -> 15        : 56      |                                        |
       16 -> 31        : 483     |****                                    |
       32 -> 63        : 1548    |************                            |
       64 -> 127       : 2634    |*********************                   |
      128 -> 255       : 2535    |*********************                   |
      256 -> 511       : 1776    |**************                          |
      512 -> 1023      : 1015    |********                                |
     1024 -> 2047      : 573     |****                                    |
     2048 -> 4095      : 488     |****                                    |
     4096 -> 8191      : 1091    |*********                               |
     8192 -> 16383     : 3078    |*************************               |
    16384 -> 32767     : 4821    |****************************************|
    32768 -> 65535     : 3318    |***************************             |
    65536 -> 131071    : 1718    |**************                          |
   131072 -> 262143    : 2220    |******************                      |
   262144 -> 524287    : 1147    |*********                               |
   524288 -> 1048575   : 1179    |*********                               |
  1048576 -> 2097151   : 822     |******                                  |
  2097152 -> 4194303   : 906     |*******                                 |
  4194304 -> 8388607   : 2148    |*****************                       |
  8388608 -> 16777215  : 4497    |*************************************   |
 16777216 -> 33554431  : 289     |**                                      |

  avg = 2041714 usecs, total: 78381401772 usecs, count: 38390

  The worst case is over 16-33 seconds, so soft lockup is triggered [2].

[Root Cause]
1) Each purge_list has the long list. The following shows the number of
   vmap_area is purged.

   crash> p vmap_nodes
   vmap_nodes = $27 = (struct vmap_node *) 0xff2de5a900100000
   crash> vmap_node 0xff2de5a900100000 128 | grep nr_purged
     nr_purged = 663070
     ...
     nr_purged = 821670
     nr_purged = 692214
     nr_purged = 726808
     ...

2) atomic_long_sub() employs the 'lock' prefix to ensure the atomic
   operation when purging each vmap_area. However, the iteration is over
   600000 vmap_area (See 'nr_purged' above).

   Here is objdump output:

     $ objdump -D vmlinux
     ffffffff813e8c80 <purge_vmap_node>:
     ...
     ffffffff813e8d70:  f0 48 29 2d 68 0c bb  lock sub %rbp,0x2bb0c68(%rip)
     ...

   Quote from "Instruction tables" pdf file [3]:
     Instructions with a LOCK prefix have a long latency that depends on
     cache organization and possibly RAM speed. If there are multiple
     processors or cores or direct memory access (DMA) devices, then all
     locked instructions will lock a cache line for exclusive access,
     which may involve RAM access. A LOCK prefix typically costs more
     than a hundred clock cycles, even on single-processor systems.

   That's why the latency of purge_vmap_node() dramatically increases
   on a many-core system: One core is busy on purging each vmap_area of
   the *long* purge_list and executing atomic_long_sub() for each
   vmap_area, while other cores free vmalloc allocations and execute
   atomic_long_add_return() in free_vmap_area_noflush().

[Solution]
Employ a local variable to record the total purged pages, and execute
atomic_long_sub() after the traversal of the purge_list is done. The
experiment result shows the latency improvement is 99%.

[Experiment Result]
1) System Configuration: Three servers (with HT-enabled) are tested.
     * 72-core server: 3rd Gen Intel Xeon Scalable Processor*1
     * 192-core server: 5th Gen Intel Xeon Scalable Processor*2
     * 448-core server: AMD Zen 4 Processor*2

2) Kernel Config
     * CONFIG_KASAN is disabled

3) The data in column "w/o patch" and "w/ patch"
     * Unit: micro seconds (us)
     * Each data is the average of 3-time measurements

         System        w/o patch (us)   w/ patch (us)    Improvement (%)
     ---------------   --------------   -------------    -------------
     72-core server          2194              14            99.36%
     192-core server       143799            1139            99.21%
     448-core server      1992122            6883            99.65%

[1] https://github.com/iovisor/bcc/blob/master/tools/funclatency.py
[2] https://gist.github.com/AdrianHuang/37c15f67b45407b83c2d32f918656c12
[3] https://www.agner.org/optimize/instruction_tables.pdf

Link: https://lkml.kernel.org/r/20240829130633.2184-1-ahuang12@lenovo.comSigned-off-by: default avatarAdrian Huang <ahuang12@lenovo.com>
Reviewed-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      409faf8c
    • Jan Kuliga's avatar
      mailmap: update entry for Jan Kuliga · 4f295229
      Jan Kuliga authored 
      Soon I won't be able to use my current email address.

Link: https://lkml.kernel.org/r/20240830095658.1203198-1-jankul@alatek.krakow.plSigned-off-by: default avatarJan Kuliga <jankul@alatek.krakow.pl>
Cc: David S. Miller <davem@davemloft.net>
Cc: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      4f295229
    • Hao Ge's avatar
      codetag: debug: mark codetags for poisoned page as empty · 5e9784e9
      Hao Ge authored 
      When PG_hwpoison pages are freed they are treated differently in
free_pages_prepare() and instead of being released they are isolated.

Page allocation tag counters are decremented at this point since the page
is considered not in use.  Later on when such pages are released by
unpoison_memory(), the allocation tag counters will be decremented again
and the following warning gets reported:

[  113.930443][ T3282] ------------[ cut here ]------------
[  113.931105][ T3282] alloc_tag was not set
[  113.931576][ T3282] WARNING: CPU: 2 PID: 3282 at ./include/linux/alloc_tag.h:130 pgalloc_tag_sub.part.66+0x154/0x164
[  113.932866][ T3282] Modules linked in: hwpoison_inject fuse ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_conntrack ebtable_nat ebtable_broute ip6table_nat ip6table_man4
[  113.941638][ T3282] CPU: 2 UID: 0 PID: 3282 Comm: madvise11 Kdump: loaded Tainted: G        W          6.11.0-rc4-dirty #18
[  113.943003][ T3282] Tainted: [W]=WARN
[  113.943453][ T3282] Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
[  113.944378][ T3282] pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[  113.945319][ T3282] pc : pgalloc_tag_sub.part.66+0x154/0x164
[  113.946016][ T3282] lr : pgalloc_tag_sub.part.66+0x154/0x164
[  113.946706][ T3282] sp : ffff800087093a10
[  113.947197][ T3282] x29: ffff800087093a10 x28: ffff0000d7a9d400 x27: ffff80008249f0a0
[  113.948165][ T3282] x26: 0000000000000000 x25: ffff80008249f2b0 x24: 0000000000000000
[  113.949134][ T3282] x23: 0000000000000001 x22: 0000000000000001 x21: 0000000000000000
[  113.950597][ T3282] x20: ffff0000c08fcad8 x19: ffff80008251e000 x18: ffffffffffffffff
[  113.952207][ T3282] x17: 0000000000000000 x16: 0000000000000000 x15: ffff800081746210
[  113.953161][ T3282] x14: 0000000000000000 x13: 205d323832335420 x12: 5b5d353031313339
[  113.954120][ T3282] x11: ffff800087093500 x10: 000000000000005d x9 : 00000000ffffffd0
[  113.955078][ T3282] x8 : 7f7f7f7f7f7f7f7f x7 : ffff80008236ba90 x6 : c0000000ffff7fff
[  113.956036][ T3282] x5 : ffff000b34bf4dc8 x4 : ffff8000820aba90 x3 : 0000000000000001
[  113.956994][ T3282] x2 : ffff800ab320f000 x1 : 841d1e35ac932e00 x0 : 0000000000000000
[  113.957962][ T3282] Call trace:
[  113.958350][ T3282]  pgalloc_tag_sub.part.66+0x154/0x164
[  113.959000][ T3282]  pgalloc_tag_sub+0x14/0x1c
[  113.959539][ T3282]  free_unref_page+0xf4/0x4b8
[  113.960096][ T3282]  __folio_put+0xd4/0x120
[  113.960614][ T3282]  folio_put+0x24/0x50
[  113.961103][ T3282]  unpoison_memory+0x4f0/0x5b0
[  113.961678][ T3282]  hwpoison_unpoison+0x30/0x48 [hwpoison_inject]
[  113.962436][ T3282]  simple_attr_write_xsigned.isra.34+0xec/0x1cc
[  113.963183][ T3282]  simple_attr_write+0x38/0x48
[  113.963750][ T3282]  debugfs_attr_write+0x54/0x80
[  113.964330][ T3282]  full_proxy_write+0x68/0x98
[  113.964880][ T3282]  vfs_write+0xdc/0x4d0
[  113.965372][ T3282]  ksys_write+0x78/0x100
[  113.965875][ T3282]  __arm64_sys_write+0x24/0x30
[  113.966440][ T3282]  invoke_syscall+0x7c/0x104
[  113.966984][ T3282]  el0_svc_common.constprop.1+0x88/0x104
[  113.967652][ T3282]  do_el0_svc+0x2c/0x38
[  113.968893][ T3282]  el0_svc+0x3c/0x1b8
[  113.969379][ T3282]  el0t_64_sync_handler+0x98/0xbc
[  113.969980][ T3282]  el0t_64_sync+0x19c/0x1a0
[  113.970511][ T3282] ---[ end trace 0000000000000000 ]---

To fix this, clear the page tag reference after the page got isolated
and accounted for.

Link: https://lkml.kernel.org/r/20240825163649.33294-1-hao.ge@linux.dev
Fixes: d224eb02 ("codetag: debug: mark codetags for reserved pages as empty")
Signed-off-by: default avatarHao Ge <gehao@kylinos.cn>
Reviewed-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Acked-by: default avatarSuren Baghdasaryan <surenb@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hao Ge <gehao@kylinos.cn>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: <stable@vger.kernel.org>	[6.10+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      5e9784e9
    • Mike Yuan's avatar
      mm/memcontrol: respect zswap.writeback setting from parent cg too · e3992573
      Mike Yuan authored 
      Currently, the behavior of zswap.writeback wrt.  the cgroup hierarchy
seems a bit odd.  Unlike zswap.max, it doesn't honor the value from parent
cgroups.  This surfaced when people tried to globally disable zswap
writeback, i.e.  reserve physical swap space only for hibernation [1] -
disabling zswap.writeback only for the root cgroup results in subcgroups
with zswap.writeback=1 still performing writeback.

The inconsistency became more noticeable after I introduced the
MemoryZSwapWriteback= systemd unit setting [2] for controlling the knob.
The patch assumed that the kernel would enforce the value of parent
cgroups.  It could probably be workarounded from systemd's side, by going
up the slice unit tree and inheriting the value.  Yet I think it's more
sensible to make it behave consistently with zswap.max and friends.

[1] https://wiki.archlinux.org/title/Power_management/Suspend_and_hibernate#Disable_zswap_writeback_to_use_the_swap_space_only_for_hibernation
[2] https://github.com/systemd/systemd/pull/31734

Link: https://lkml.kernel.org/r/20240823162506.12117-1-me@yhndnzj.com
Fixes: 501a06fe ("zswap: memcontrol: implement zswap writeback disabling")
Signed-off-by: default avatarMike Yuan <me@yhndnzj.com>
Reviewed-by: default avatarNhat Pham <nphamcs@gmail.com>
Acked-by: default avatarYosry Ahmed <yosryahmed@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      e3992573
    • Marc Zyngier's avatar
      scripts: fix gfp-translate after ___GFP_*_BITS conversion to an enum · a3f6a89c
      Marc Zyngier authored 
      Richard reports that since 772dd034 ("mm: enumerate all gfp flags"),
gfp-translate is broken, as the bit numbers are implicit, leaving the
shell script unable to extract them.  Even more, some bits are now at a
variable location, making it double extra hard to parse using a simple
shell script.

Use a brute-force approach to the problem by generating a small C stub
that will use the enum to dump the interesting bits.

As an added bonus, we are now able to identify invalid bits for a given
configuration.  As an added drawback, we cannot parse include files that
predate this change anymore.  Tough luck.

Link: https://lkml.kernel.org/r/20240823163850.3791201-1-maz@kernel.org
Fixes: 772dd034 ("mm: enumerate all gfp flags")
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Reported-by: default avatarRichard Weinberger <richard@nod.at>
Cc: Petr Tesařík <petr@tesarici.cz>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      a3f6a89c
    • Usama Arif's avatar
      Revert "mm: skip CMA pages when they are not available" · bfe0857c
      Usama Arif authored 
      This reverts commit 5da226db ("mm: skip CMA pages when they are not
available") and b7108d66 ("Multi-gen LRU: skip CMA pages when they are
not eligible").

lruvec->lru_lock is highly contended and is held when calling
isolate_lru_folios.  If the lru has a large number of CMA folios
consecutively, while the allocation type requested is not MIGRATE_MOVABLE,
isolate_lru_folios can hold the lock for a very long time while it skips
those.  For FIO workload, ~150million order=0 folios were skipped to
isolate a few ZONE_DMA folios [1].  This can cause lockups [1] and high
memory pressure for extended periods of time [2].

Remove skipping CMA for MGLRU as well, as it was introduced in sort_folio
for the same resaon as 5da226db.

[1] https://lore.kernel.org/all/CAOUHufbkhMZYz20aM_3rHZ3OcK4m2puji2FGpUpn_-DevGk3Kg@mail.gmail.com/
[2] https://lore.kernel.org/all/ZrssOrcJIDy8hacI@gmail.com/

[usamaarif642@gmail.com: also revert b7108d66, per Johannes]
  Link: https://lkml.kernel.org/r/9060a32d-b2d7-48c0-8626-1db535653c54@gmail.com
  Link: https://lkml.kernel.org/r/357ac325-4c61-497a-92a3-bdbd230d5ec9@gmail.com
Link: https://lkml.kernel.org/r/9060a32d-b2d7-48c0-8626-1db535653c54@gmail.com
Fixes: 5da226db ("mm: skip CMA pages when they are not available")
Signed-off-by: default avatarUsama Arif <usamaarif642@gmail.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Bharata B Rao <bharata@amd.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zhaoyang Huang <huangzhaoyang@gmail.com>
Cc: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      bfe0857c
    • Liam R. Howlett's avatar
      maple_tree: remove rcu_read_lock() from mt_validate() · f806de88
      Liam R. Howlett authored 
      The write lock should be held when validating the tree to avoid updates
racing with checks.  Holding the rcu read lock during a large tree
validation may also cause a prolonged rcu read window and "rcu_preempt
detected stalls" warnings.

Link: https://lore.kernel.org/all/0000000000001d12d4062005aea1@google.com/
Link: https://lkml.kernel.org/r/20240820175417.2782532-1-Liam.Howlett@oracle.com
Fixes: 54a611b6 ("Maple Tree: add new data structure")
Signed-off-by: default avatarLiam R. Howlett <Liam.Howlett@Oracle.com>
Reported-by: syzbot+036af2f0c7338a33b0cd@syzkaller.appspotmail.com
Cc: Hillf Danton <hdanton@sina.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      f806de88
    • Petr Tesarik's avatar
      kexec_file: fix elfcorehdr digest exclusion when CONFIG_CRASH_HOTPLUG=y · 6dacd79d
      Petr Tesarik authored 
      Fix the condition to exclude the elfcorehdr segment from the SHA digest
calculation.

The j iterator is an index into the output sha_regions[] array, not into
the input image->segment[] array.  Once it reaches
image->elfcorehdr_index, all subsequent segments are excluded.  Besides,
if the purgatory segment precedes the elfcorehdr segment, the elfcorehdr
may be wrongly included in the calculation.

Link: https://lkml.kernel.org/r/20240805150750.170739-1-petr.tesarik@suse.com
Fixes: f7cc804a ("kexec: exclude elfcorehdr from the segment digest")
Signed-off-by: default avatarPetr Tesarik <ptesarik@suse.com>
Acked-by: default avatarBaoquan He <bhe@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Eric DeVolder <eric_devolder@yahoo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      6dacd79d
    • Hao Ge's avatar
      mm/slub: add check for s->flags in the alloc_tagging_slab_free_hook · ab7ca095
      Hao Ge authored 
      When enable CONFIG_MEMCG & CONFIG_KFENCE & CONFIG_KMEMLEAK, the following
warning always occurs,This is because the following call stack occurred:
mem_pool_alloc
    kmem_cache_alloc_noprof
        slab_alloc_node
            kfence_alloc

Once the kfence allocation is successful,slab->obj_exts will not be empty,
because it has already been assigned a value in kfence_init_pool.

Since in the prepare_slab_obj_exts_hook function,we perform a check for
s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE),the alloc_tag_add function
will not be called as a result.Therefore,ref->ct remains NULL.

However,when we call mem_pool_free,since obj_ext is not empty, it
eventually leads to the alloc_tag_sub scenario being invoked.  This is
where the warning occurs.

So we should add corresponding checks in the alloc_tagging_slab_free_hook.
For __GFP_NO_OBJ_EXT case,I didn't see the specific case where it's using
kfence,so I won't add the corresponding check in
alloc_tagging_slab_free_hook for now.

[    3.734349] ------------[ cut here ]------------
[    3.734807] alloc_tag was not set
[    3.735129] WARNING: CPU: 4 PID: 40 at ./include/linux/alloc_tag.h:130 kmem_cache_free+0x444/0x574
[    3.735866] Modules linked in: autofs4
[    3.736211] CPU: 4 UID: 0 PID: 40 Comm: ksoftirqd/4 Tainted: G        W          6.11.0-rc3-dirty #1
[    3.736969] Tainted: [W]=WARN
[    3.737258] Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
[    3.737875] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    3.738501] pc : kmem_cache_free+0x444/0x574
[    3.738951] lr : kmem_cache_free+0x444/0x574
[    3.739361] sp : ffff80008357bb60
[    3.739693] x29: ffff80008357bb70 x28: 0000000000000000 x27: 0000000000000000
[    3.740338] x26: ffff80008207f000 x25: ffff000b2eb2fd60 x24: ffff0000c0005700
[    3.740982] x23: ffff8000804229e4 x22: ffff800082080000 x21: ffff800081756000
[    3.741630] x20: fffffd7ff8253360 x19: 00000000000000a8 x18: ffffffffffffffff
[    3.742274] x17: ffff800ab327f000 x16: ffff800083398000 x15: ffff800081756df0
[    3.742919] x14: 0000000000000000 x13: 205d344320202020 x12: 5b5d373038343337
[    3.743560] x11: ffff80008357b650 x10: 000000000000005d x9 : 00000000ffffffd0
[    3.744231] x8 : 7f7f7f7f7f7f7f7f x7 : ffff80008237bad0 x6 : c0000000ffff7fff
[    3.744907] x5 : ffff80008237ba78 x4 : ffff8000820bbad0 x3 : 0000000000000001
[    3.745580] x2 : 68d66547c09f7800 x1 : 68d66547c09f7800 x0 : 0000000000000000
[    3.746255] Call trace:
[    3.746530]  kmem_cache_free+0x444/0x574
[    3.746931]  mem_pool_free+0x44/0xf4
[    3.747306]  free_object_rcu+0xc8/0xdc
[    3.747693]  rcu_do_batch+0x234/0x8a4
[    3.748075]  rcu_core+0x230/0x3e4
[    3.748424]  rcu_core_si+0x14/0x1c
[    3.748780]  handle_softirqs+0x134/0x378
[    3.749189]  run_ksoftirqd+0x70/0x9c
[    3.749560]  smpboot_thread_fn+0x148/0x22c
[    3.749978]  kthread+0x10c/0x118
[    3.750323]  ret_from_fork+0x10/0x20
[    3.750696] ---[ end trace 0000000000000000 ]---

Link: https://lkml.kernel.org/r/20240816013336.17505-1-hao.ge@linux.dev
Fixes: 4b873696 ("mm/slab: add allocation accounting into slab allocation and free paths")
Signed-off-by: default avatarHao Ge <gehao@kylinos.cn>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      ab7ca095
    • Ryusuke Konishi's avatar
      nilfs2: fix state management in error path of log writing function · 6576dd66
      Ryusuke Konishi authored 
      After commit a694291a ("nilfs2: separate wait function from
nilfs_segctor_write") was applied, the log writing function
nilfs_segctor_do_construct() was able to issue I/O requests continuously
even if user data blocks were split into multiple logs across segments,
but two potential flaws were introduced in its error handling.

First, if nilfs_segctor_begin_construction() fails while creating the
second or subsequent logs, the log writing function returns without
calling nilfs_segctor_abort_construction(), so the writeback flag set on
pages/folios will remain uncleared.  This causes page cache operations to
hang waiting for the writeback flag.  For example,
truncate_inode_pages_final(), which is called via nilfs_evict_inode() when
an inode is evicted from memory, will hang.

Second, the NILFS_I_COLLECTED flag set on normal inodes remain uncleared. 
As a result, if the next log write involves checkpoint creation, that's
fine, but if a partial log write is performed that does not, inodes with
NILFS_I_COLLECTED set are erroneously removed from the "sc_dirty_files"
list, and their data and b-tree blocks may not be written to the device,
corrupting the block mapping.

Fix these issues by uniformly calling nilfs_segctor_abort_construction()
on failure of each step in the loop in nilfs_segctor_do_construct(),
having it clean up logs and segment usages according to progress, and
correcting the conditions for calling nilfs_redirty_inodes() to ensure
that the NILFS_I_COLLECTED flag is cleared.

Link: https://lkml.kernel.org/r/20240814101119.4070-1-konishi.ryusuke@gmail.com
Fixes: a694291a ("nilfs2: separate wait function from nilfs_segctor_write")
Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      6576dd66
    • Ryusuke Konishi's avatar
      nilfs2: fix missing cleanup on rollforward recovery error · 5787fcaa
      Ryusuke Konishi authored 
      In an error injection test of a routine for mount-time recovery, KASAN
found a use-after-free bug.

It turned out that if data recovery was performed using partial logs
created by dsync writes, but an error occurred before starting the log
writer to create a recovered checkpoint, the inodes whose data had been
recovered were left in the ns_dirty_files list of the nilfs object and
were not freed.

Fix this issue by cleaning up inodes that have read the recovery data if
the recovery routine fails midway before the log writer starts.

Link: https://lkml.kernel.org/r/20240810065242.3701-1-konishi.ryusuke@gmail.com
Fixes: 0f3e1c7f ("nilfs2: recovery functions")
Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      5787fcaa
    • Ryusuke Konishi's avatar
      nilfs2: protect references to superblock parameters exposed in sysfs · 68340825
      Ryusuke Konishi authored 
      The superblock buffers of nilfs2 can not only be overwritten at runtime
for modifications/repairs, but they are also regularly swapped, replaced
during resizing, and even abandoned when degrading to one side due to
backing device issues.  So, accessing them requires mutual exclusion using
the reader/writer semaphore "nilfs->ns_sem".

Some sysfs attribute show methods read this superblock buffer without the
necessary mutual exclusion, which can cause problems with pointer
dereferencing and memory access, so fix it.

Link: https://lkml.kernel.org/r/20240811100320.9913-1-konishi.ryusuke@gmail.com
Fixes: da7141fb ("nilfs2: add /sys/fs/nilfs2/<device> group")
Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      68340825
    • Jann Horn's avatar
      userfaultfd: don't BUG_ON() if khugepaged yanks our page table · 4828d207
      Jann Horn authored 
      Since khugepaged was changed to allow retracting page tables in file
mappings without holding the mmap lock, these BUG_ON()s are wrong - get
rid of them.

We could also remove the preceding "if (unlikely(...))" block, but then we
could reach pte_offset_map_lock() with transhuge pages not just for file
mappings but also for anonymous mappings - which would probably be fine
but I think is not necessarily expected.

Link: https://lkml.kernel.org/r/20240813-uffd-thp-flip-fix-v2-2-5efa61078a41@google.com
Fixes: 1d65b771 ("mm/khugepaged: retract_page_tables() without mmap or vma lock")
Signed-off-by: default avatarJann Horn <jannh@google.com>
Reviewed-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      4828d207
    • Jann Horn's avatar
      userfaultfd: fix checks for huge PMDs · 71c186ef
      Jann Horn authored 
      Patch series "userfaultfd: fix races around pmd_trans_huge() check", v2.

The pmd_trans_huge() code in mfill_atomic() is wrong in three different
ways depending on kernel version:

1. The pmd_trans_huge() check is racy and can lead to a BUG_ON() (if you hit
   the right two race windows) - I've tested this in a kernel build with
   some extra mdelay() calls. See the commit message for a description
   of the race scenario.
   On older kernels (before 6.5), I think the same bug can even
   theoretically lead to accessing transhuge page contents as a page table
   if you hit the right 5 narrow race windows (I haven't tested this case).
2. As pointed out by Qi Zheng, pmd_trans_huge() is not sufficient for
   detecting PMDs that don't point to page tables.
   On older kernels (before 6.5), you'd just have to win a single fairly
   wide race to hit this.
   I've tested this on 6.1 stable by racing migration (with a mdelay()
   patched into try_to_migrate()) against UFFDIO_ZEROPAGE - on my x86
   VM, that causes a kernel oops in ptlock_ptr().
3. On newer kernels (>=6.5), for shmem mappings, khugepaged is allowed
   to yank page tables out from under us (though I haven't tested that),
   so I think the BUG_ON() checks in mfill_atomic() are just wrong.

I decided to write two separate fixes for these (one fix for bugs 1+2, one
fix for bug 3), so that the first fix can be backported to kernels
affected by bugs 1+2.


This patch (of 2):

This fixes two issues.

I discovered that the following race can occur:

  mfill_atomic                other thread
  ============                ============
                              <zap PMD>
  pmdp_get_lockless() [reads none pmd]
  <bail if trans_huge>
  <if none:>
                              <pagefault creates transhuge zeropage>
    __pte_alloc [no-op]
                              <zap PMD>
  <bail if pmd_trans_huge(*dst_pmd)>
  BUG_ON(pmd_none(*dst_pmd))

I have experimentally verified this in a kernel with extra mdelay() calls;
the BUG_ON(pmd_none(*dst_pmd)) triggers.

On kernels newer than commit 0d940a9b ("mm/pgtable: allow
pte_offset_map[_lock]() to fail"), this can't lead to anything worse than
a BUG_ON(), since the page table access helpers are actually designed to
deal with page tables concurrently disappearing; but on older kernels
(<=6.4), I think we could probably theoretically race past the two
BUG_ON() checks and end up treating a hugepage as a page table.

The second issue is that, as Qi Zheng pointed out, there are other types
of huge PMDs that pmd_trans_huge() can't catch: devmap PMDs and swap PMDs
(in particular, migration PMDs).

On <=6.4, this is worse than the first issue: If mfill_atomic() runs on a
PMD that contains a migration entry (which just requires winning a single,
fairly wide race), it will pass the PMD to pte_offset_map_lock(), which
assumes that the PMD points to a page table.

Breakage follows: First, the kernel tries to take the PTE lock (which will
crash or maybe worse if there is no "struct page" for the address bits in
the migration entry PMD - I think at least on X86 there usually is no
corresponding "struct page" thanks to the PTE inversion mitigation, amd64
looks different).

If that didn't crash, the kernel would next try to write a PTE into what
it wrongly thinks is a page table.

As part of fixing these issues, get rid of the check for pmd_trans_huge()
before __pte_alloc() - that's redundant, we're going to have to check for
that after the __pte_alloc() anyway.

Backport note: pmdp_get_lockless() is pmd_read_atomic() in older kernels.

Link: https://lkml.kernel.org/r/20240813-uffd-thp-flip-fix-v2-0-5efa61078a41@google.com
Link: https://lkml.kernel.org/r/20240813-uffd-thp-flip-fix-v2-1-5efa61078a41@google.com
Fixes: c1a4de99 ("userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation")
Signed-off-by: default avatarJann Horn <jannh@google.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      71c186ef
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