KCSAN: data-race in fsnotify / fsnotify_detach_mark (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 418baf2c Linux 5.10-rc5
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17c0a9cd500000
kernel config: https://syzkaller.appspot.com/x/.config?x=cf114765a0c30afa
dashboard link: https://syzkaller.appspot.com/bug?extid=25e6de767b2f25a71e64
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
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.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+25e6de...@syzkaller.appspotmail.com

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

write to 0xffff88810a82c9d4 of 4 bytes by task 1612 on cpu 0:
fsnotify_detach_mark+0x80/0x120 fs/notify/mark.c:390
fsnotify_clear_marks_by_group+0x29b/0x3e0 fs/notify/mark.c:761
fsnotify_destroy_group+0x51/0x170 fs/notify/group.c:61
fanotify_release+0x2c5/0x2e0 fs/notify/fanotify/fanotify_user.c:623
__fput+0x243/0x4d0 fs/file_table.c:281
____fput+0x11/0x20 fs/file_table.c:314
task_work_run+0x8e/0x110 kernel/task_work.c:151
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810a82c9d4 of 4 bytes by task 8445 on cpu 1:
send_to_group fs/notify/fsnotify.c:299 [inline]
fsnotify+0x803/0xe70 fs/notify/fsnotify.c:506
fsnotify_parent include/linux/fsnotify.h:71 [inline]
fsnotify_file include/linux/fsnotify.h:90 [inline]
fsnotify_modify include/linux/fsnotify.h:255 [inline]
vfs_write+0x451/0x7c0 fs/read_write.c:609
ksys_write+0xce/0x180 fs/read_write.c:658
__do_sys_write fs/read_write.c:670 [inline]
__se_sys_write fs/read_write.c:667 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:667
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8445 Comm: syz-fuzzer Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.