KCSAN: data-race in __dentry_kill / d_set_d_op (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 521b619a Merge tag 'linux-kselftest-kunit-fixes-5.10-rc3' ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11a088a4500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=742cc8094ed5a2cde98d
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+742cc8...@syzkaller.appspotmail.com

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

read-write to 0xffff888057973cc0 of 4 bytes by task 3980 on cpu 1:
d_set_d_op+0x14c/0x1e0 fs/dcache.c:1875
simple_lookup+0x78/0x90 fs/libfs.c:73
__lookup_slow+0x181/0x250 fs/namei.c:1544
lookup_slow fs/namei.c:1561 [inline]
walk_component+0x2a5/0x350 fs/namei.c:1861
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:3109 [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

read to 0xffff888057973cc0 of 4 bytes by task 3953 on cpu 0:
dentry_unlist fs/dcache.c:544 [inline]
__dentry_kill+0x1e7/0x450 fs/dcache.c:575
dentry_kill fs/dcache.c:692 [inline]
dput+0x203/0x420 fs/dcache.c:878
handle_mounts fs/namei.c:1389 [inline]
step_into+0x43b/0xe80 fs/namei.c:1691
walk_component+0x190/0x350 fs/namei.c:1867
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:3109 [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: 0 PID: 3953 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
==================================================================


---
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.