[moderation] [fs?] KCSAN: data-race in fsnotify / fsnotify_detach_mark (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 651690480a96 Merge tag 'spi-fix-v7.0-rc2' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1794db5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6b32b22d8934c136
dashboard link: https://syzkaller.appspot.com/bug?extid=4d3a08edcc44ff216ac1
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [amir...@gmail.com ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2f2710e94d1e/disk-65169048.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/772300804621/vmlinux-65169048.xz
kernel image: https://storage.googleapis.com/syzbot-assets/09145fa6db2a/bzImage-65169048.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4d3a08...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in fsnotify / fsnotify_detach_mark

write to 0xffff888105359684 of 4 bytes by task 454 on cpu 0:
fsnotify_detach_mark+0xb9/0x160 fs/notify/mark.c:558
fsnotify_clear_marks_by_group+0x301/0x4b0 fs/notify/mark.c:1031
fsnotify_destroy_group+0x53/0x180 fs/notify/group.c:61
inotify_release+0x1f/0x30 fs/notify/inotify/inotify_user.c:308
__fput+0x29b/0x650 fs/file_table.c:469
____fput+0x1c/0x30 fs/file_table.c:497
task_work_run+0x130/0x1a0 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x4ae/0x1600 kernel/exit.c:976
do_group_exit+0xfe/0x140 kernel/exit.c:1118
get_signal+0xe54/0xf60 kernel/signal.c:3034
arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105359684 of 4 bytes by task 441 on cpu 1:
send_to_group fs/notify/fsnotify.c:349 [inline]
fsnotify+0xd77/0x1730 fs/notify/fsnotify.c:592
__fsnotify_parent+0x358/0x3a0 fs/notify/fsnotify.c:238
fsnotify_parent include/linux/fsnotify.h:96 [inline]
fsnotify_path include/linux/fsnotify.h:113 [inline]
fsnotify_file include/linux/fsnotify.h:127 [inline]
fsnotify_modify include/linux/fsnotify.h:433 [inline]
__kernel_write_iter+0x4c9/0x590 fs/read_write.c:625
dump_emit_page fs/coredump.c:1299 [inline]
dump_user_range+0xa7d/0xdb0 fs/coredump.c:1373
elf_core_dump+0x21a2/0x2330 fs/binfmt_elf.c:2110
coredump_write+0xacc/0xdd0 fs/coredump.c:1050
do_coredump fs/coredump.c:1127 [inline]
vfs_coredump+0x26c7/0x3130 fs/coredump.c:1201
get_signal+0xd80/0xf60 kernel/signal.c:3019
arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000013 -> 0x00000010

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 441 Comm: syz.7.13551 Tainted: G W syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================


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