KCSAN: data-race in __fsnotify_parent / d_set_mounted (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 127c501a Merge tag '5.10-rc5-smb3-fixes' of git://git.samb..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12923f49500000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9b19d1bde60f8d
dashboard link: https://syzkaller.appspot.com/bug?extid=c66fbc0578223d433d89
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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+c66fbc...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __fsnotify_parent / d_set_mounted

write to 0xffff88810bf5ba80 of 4 bytes by task 21615 on cpu 1:
d_set_mounted+0x112/0x190 fs/dcache.c:1459
get_mountpoint+0x1ac/0x2f0 fs/namespace.c:740
lock_mount+0x86/0x1d0 fs/namespace.c:2200
do_move_mount+0x21/0x810 fs/namespace.c:2667
do_move_mount_old fs/namespace.c:2751 [inline]
path_mount+0xb1e/0x1c10 fs/namespace.c:3203
do_mount fs/namespace.c:3218 [inline]
__do_sys_mount fs/namespace.c:3426 [inline]
__se_sys_mount+0x23d/0x2e0 fs/namespace.c:3403
__x64_sys_mount+0x63/0x70 fs/namespace.c:3403
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810bf5ba80 of 4 bytes by task 21608 on cpu 0:
__fsnotify_parent+0x7d/0x430 fs/notify/fsnotify.c:180
fsnotify_parent include/linux/fsnotify.h:68 [inline]
fsnotify_file include/linux/fsnotify.h:90 [inline]
fsnotify_modify include/linux/fsnotify.h:255 [inline]
vfs_write+0x430/0x7c0 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: 0 PID: 21608 Comm: syz-executor.3 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.