KCSAN: data-race in fast_dput / vfs_unlink

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f01da525 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=152c92add00000
kernel config: https://syzkaller.appspot.com/x/.config?x=ff91eb7f28bdda65
dashboard link: https://syzkaller.appspot.com/bug?extid=a3b33052a328cbd0e4e6
compiler: Debian clang version 11.0.1-2
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+a3b330...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in fast_dput / vfs_unlink

write to 0xffff8881066c6cc0 of 4 bytes by task 17728 on cpu 0:
dont_mount include/linux/dcache.h:358 [inline]
vfs_unlink+0x289/0x400 fs/namei.c:4027
do_unlinkat+0x238/0x4f0 fs/namei.c:4092
__do_sys_unlink fs/namei.c:4139 [inline]
__se_sys_unlink fs/namei.c:4137 [inline]
__x64_sys_unlink+0x2c/0x30 fs/namei.c:4137
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881066c6cc0 of 4 bytes by task 1034 on cpu 1:
fast_dput+0x14/0x1c0 fs/dcache.c:749
dput+0x26/0x360 fs/dcache.c:875
path_put+0x1b/0x30 fs/namei.c:546
do_readlinkat+0x188/0x200 fs/stat.c:440
__do_sys_readlink fs/stat.c:458 [inline]
__se_sys_readlink fs/stat.c:455 [inline]
__x64_sys_readlink+0x43/0x50 fs/stat.c:455
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1034 Comm: systemd-udevd Not tainted 5.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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