[moderation] [fs?] KCSAN: data-race in fsnotify_detach_mark / fsnotify_handle_inode_event (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 90b83efa6701 Merge tag 'bpf-next-6.16' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14c42482580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c97eebd62683a33d
dashboard link: https://syzkaller.appspot.com/bug?extid=21ccf00ef85c17ca9d58
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
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/93a383fbc67f/disk-90b83efa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ef537c45c4b6/vmlinux-90b83efa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/871c4dd4722e/bzImage-90b83efa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+21ccf0...@syzkaller.appspotmail.com

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

write to 0xffff888103ccd7c4 of 4 bytes by task 3469 on cpu 0:
fsnotify_detach_mark+0xba/0x160 fs/notify/mark.c:554
fsnotify_destroy_mark+0x70/0x150 fs/notify/mark.c:596
__do_sys_inotify_rm_watch fs/notify/inotify/inotify_user.c:805 [inline]
__se_sys_inotify_rm_watch+0xe8/0x170 fs/notify/inotify/inotify_user.c:786
__x64_sys_inotify_rm_watch+0x31/0x40 fs/notify/inotify/inotify_user.c:786
x64_sys_call+0x1fe9/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:256
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103ccd7c4 of 4 bytes by task 4924 on cpu 1:
fsnotify_handle_inode_event+0x125/0x220 fs/notify/fsnotify.c:313
fsnotify_handle_event fs/notify/fsnotify.c:376 [inline]
send_to_group fs/notify/fsnotify.c:424 [inline]
fsnotify+0x13c9/0x14b0 fs/notify/fsnotify.c:641
__fsnotify_parent+0x2ed/0x330 fs/notify/fsnotify.c:287
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_close include/linux/fsnotify.h:482 [inline]
__fput+0x1de/0x650 fs/file_table.c:451
fput_close_sync+0x6e/0x120 fs/file_table.c:570
__do_sys_close fs/open.c:1589 [inline]
__se_sys_close fs/open.c:1574 [inline]
__x64_sys_close+0x56/0xf0 fs/open.c:1574
x64_sys_call+0x2747/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:4
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000003 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4924 Comm: syz-executor Not tainted 6.15.0-syzkaller-07774-g90b83efa6701 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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