KCSAN: data-race in d_delete / lookup_fast (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4429f14a Merge tag 'block-5.10-2020-11-07' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11cedd46500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=f92850396011d2eb679f
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+f92850...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in d_delete / lookup_fast

read-write to 0xffff88800901a480 of 4 bytes by task 14900 on cpu 1:
d_delete+0x66/0xa0 fs/dcache.c:2469
vfs_unlink+0x38f/0x3b0 fs/namei.c:3847
do_unlinkat+0x28a/0x4d0 fs/namei.c:3897
__do_sys_unlink fs/namei.c:3943 [inline]
__se_sys_unlink fs/namei.c:3941 [inline]
__x64_sys_unlink+0x2c/0x30 fs/namei.c:3941
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88800901a480 of 4 bytes by task 4894 on cpu 0:
d_revalidate fs/namei.c:767 [inline]
lookup_fast+0x15f/0x370 fs/namei.c:1493
walk_component+0x5c/0x350 fs/namei.c:1857
lookup_last fs/namei.c:2310 [inline]
path_lookupat+0x11d/0x550 fs/namei.c:2334
filename_lookup+0xf2/0x380 fs/namei.c:2367
user_path_at_empty+0x3b/0x50 fs/namei.c:2647
do_readlinkat+0x87/0x200 fs/stat.c:407
__do_sys_readlink fs/stat.c:440 [inline]
__se_sys_readlink fs/stat.c:437 [inline]
__x64_sys_readlink+0x43/0x50 fs/stat.c:437
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: 4894 Comm: systemd-udevd Not tainted 5.10.0-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.