[syzbot] KCSAN: data-race in __se_sys_inotify_add_watch / fsnotify_handle_inode_event

[syzbot] KCSAN: data-race in __se_sys_inotify_add_watch / fsnotify_handle_inode_event

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    f49a343b305c Merge tag 'pinctrl-v7.3-2' of git://git.kerne..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1244d205580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ea1e6d8de13bab08
dashboard link: https://syzkaller.appspot.com/bug?extid=181b8b439f5207144b16
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10737c5e580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+181b8b439f5207144b16@syzkaller.appspotmail.com

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

write to 0xffff88811afe9be0 of 4 bytes by task 3651 on cpu 0:
 inotify_update_existing_watch fs/notify/inotify/inotify_user.c:558 [inline]
 inotify_update_watch fs/notify/inotify/inotify_user.c:632 [inline]
 __do_sys_inotify_add_watch fs/notify/inotify/inotify_user.c:769 [inline]
 __se_sys_inotify_add_watch+0x2ea/0x720 fs/notify/inotify/inotify_user.c:717
 __x64_sys_inotify_add_watch+0x43/0x50 fs/notify/inotify/inotify_user.c:717
 x64_sys_call+0xa19/0x2550 arch/x86/include/generated/asm/syscalls_64.h:255
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811afe9be0 of 4 bytes by task 3653 on cpu 1:
 fsnotify_handle_inode_event+0x18a/0x230 fs/notify/fsnotify.c:272
 fsnotify_handle_event fs/notify/fsnotify.c:330 [inline]
 send_to_group fs/notify/fsnotify.c:378 [inline]
 fsnotify+0x16ae/0x1860 fs/notify/fsnotify.c:597
 __fsnotify_parent+0x2f8/0x3a0 fs/notify/fsnotify.c:241
 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:461 [inline]
 __fput+0x1e2/0x630 fs/file_table.c:498
 fput_close_sync+0xad/0x190 fs/file_table.c:617
 __do_sys_close fs/open.c:1560 [inline]
 __se_sys_close fs/open.c:1545 [inline]
 __x64_sys_close+0x55/0xf0 fs/open.c:1545
 x64_sys_call+0x812/0x2550 arch/x86/include/generated/asm/syscalls_64.h:4
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00002018 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3653 Comm: syz-executor126 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================


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