[moderation] [fs?] KCSAN: data-race in __dentry_kill / d_walk

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7521f258ea30 Merge tag 'mm-hotfixes-stable-2024-02-10-11-1..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13eecd20180000
kernel config: https://syzkaller.appspot.com/x/.config?x=3cd0dc1b46a5bc5c
dashboard link: https://syzkaller.appspot.com/bug?extid=54eabfcb4a696e12b7d1
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/13bab0f1fd7a/disk-7521f258.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b8ba502ce3fb/vmlinux-7521f258.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1a60cc363ef5/bzImage-7521f258.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+54eabf...@syzkaller.appspotmail.com

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

write to 0xffff8881265f46c0 of 4 bytes by task 29737 on cpu 1:
d_lru_del fs/dcache.c:437 [inline]
__dentry_kill+0x9a/0x4a0 fs/dcache.c:598
dput+0x54/0xc0 fs/dcache.c:845
__fput+0x41d/0x630 fs/file_table.c:384
____fput+0x15/0x20 fs/file_table.c:404
task_work_run+0x135/0x1a0 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x604/0x16d0 kernel/exit.c:871
do_group_exit+0x101/0x150 kernel/exit.c:1020
get_signal+0xf4e/0x10a0 kernel/signal.c:2893
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop kernel/entry/common.c:105 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
irqentry_exit_to_user_mode+0x9c/0x130 kernel/entry/common.c:225
irqentry_exit+0x12/0x40 kernel/entry/common.c:328
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

read to 0xffff8881265f46c0 of 4 bytes by task 3254 on cpu 0:
d_walk+0x272/0x490 fs/dcache.c:1250
shrink_dcache_parent+0x84/0x1b0 fs/dcache.c:1487
vfs_rmdir+0x283/0x2f0 fs/namei.c:4209
do_rmdir+0x194/0x320 fs/namei.c:4264
__do_sys_unlinkat fs/namei.c:4440 [inline]
__se_sys_unlinkat fs/namei.c:4434 [inline]
__x64_sys_unlinkat+0xa4/0xb0 fs/namei.c:4434
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00280100 -> 0x00000100

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3254 Comm: syz-fuzzer Not tainted 6.8.0-rc3-syzkaller-00317-g7521f258ea30 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


---
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.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup