KCSAN: data-race in __dentry_kill / lookup_fast (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aae5ab85 Merge tag 'riscv-for-linus-5.10-rc6' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1372eb65500000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9b19d1bde60f8d
dashboard link: https://syzkaller.appspot.com/bug?extid=b9cbdab034e00e018445
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+b9cbda...@syzkaller.appspotmail.com

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

read-write to 0xffff888009ba4900 of 4 bytes by task 19 on cpu 0:
dentry_unlist fs/dcache.c:519 [inline]
__dentry_kill+0x13f/0x450 fs/dcache.c:575
dentry_kill fs/dcache.c:692 [inline]
dput+0x203/0x420 fs/dcache.c:878
handle_remove drivers/base/devtmpfs.c:340 [inline]
handle drivers/base/devtmpfs.c:379 [inline]
devtmpfs_work_loop+0x507/0x870 drivers/base/devtmpfs.c:392
devtmpfsd+0x33/0x40 drivers/base/devtmpfs.c:434
kthread+0x1fd/0x220 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff888009ba4900 of 4 bytes by task 22961 on cpu 1:
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
user_path_at include/linux/namei.h:59 [inline]
vfs_statx+0x90/0x270 fs/stat.c:185
vfs_fstatat fs/stat.c:207 [inline]
vfs_lstat include/linux/fs.h:3125 [inline]
__do_sys_newlstat fs/stat.c:362 [inline]
__se_sys_newlstat+0x46/0x250 fs/stat.c:356
__x64_sys_newlstat+0x2d/0x40 fs/stat.c:356
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: 22961 Comm: systemd-udevd Not tainted 5.10.0-rc5-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.