KCSAN: data-race in dentry_lru_isolate_shrink / may_delete

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 659caaf6 Merge tag 'ceph-for-5.10-rc3' of git://github.com..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=171a7b82500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=82292fb8e493fd8979c3
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+82292f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in dentry_lru_isolate_shrink / may_delete

write to 0xffff88801258ed80 of 4 bytes by task 8191 on cpu 0:
d_lru_shrink_move fs/dcache.c:453 [inline]
dentry_lru_isolate_shrink+0x7b/0x100 fs/dcache.c:1240
__list_lru_walk_one+0xfb/0x300 mm/list_lru.c:222
list_lru_walk_one mm/list_lru.c:266 [inline]
list_lru_walk_node+0x63/0x1a0 mm/list_lru.c:295
list_lru_walk include/linux/list_lru.h:215 [inline]
shrink_dcache_sb+0x97/0x1c0 fs/dcache.c:1259
reconfigure_super+0x267/0x4d0 fs/super.c:940
do_remount fs/namespace.c:2612 [inline]
path_mount+0x13b1/0x1c10 fs/namespace.c:3197
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 0xffff88801258ed80 of 4 bytes by task 8474 on cpu 1:
may_delete+0x2f7/0x420 fs/namei.c:2707
vfs_rmdir+0x25/0x290 fs/namei.c:3694
do_rmdir+0x16e/0x300 fs/namei.c:3774
__do_sys_rmdir fs/namei.c:3792 [inline]
__se_sys_rmdir fs/namei.c:3790 [inline]
__x64_sys_rmdir+0x2c/0x30 fs/namei.c:3790
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: 8474 Comm: syz-executor.1 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.