[moderation] [fs?] KCSAN: data-race in __dentry_kill / __dentry_kill (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 02adc1490e6d Merge tag 'spi-fix-v6.16-rc1' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12745d70580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f437300db311c188
dashboard link: https://syzkaller.appspot.com/bug?extid=155fa09a20bcdff536d4
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e50e82c70a27/disk-02adc149.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3744831c0ef7/vmlinux-02adc149.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7e2fbf67e791/bzImage-02adc149.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+155fa0...@syzkaller.appspotmail.com

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

write to 0xffff8881198f2f00 of 4 bytes by task 3313 on cpu 0:
d_lru_del fs/dcache.c:503 [inline]
__dentry_kill+0xa8/0x4b0 fs/dcache.c:664
dput+0x5e/0xd0 fs/dcache.c:911
proc_invalidate_siblings_dcache+0x1c8/0x2a0 fs/proc/inode.c:143
proc_flush_pid+0x1d/0x30 fs/proc/base.c:3484
release_task+0x992/0xb60 kernel/exit.c:292
wait_task_zombie kernel/exit.c:1266 [inline]
wait_consider_task+0x113f/0x1650 kernel/exit.c:1493
do_wait_thread kernel/exit.c:1556 [inline]
__do_wait+0xfa/0x510 kernel/exit.c:1674
do_wait+0xb7/0x260 kernel/exit.c:1708
kernel_wait4+0x16b/0x1e0 kernel/exit.c:1867
__do_sys_wait4 kernel/exit.c:1895 [inline]
__se_sys_wait4 kernel/exit.c:1891 [inline]
__x64_sys_wait4+0x91/0x120 kernel/exit.c:1891
x64_sys_call+0x26c8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:62
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881198f2f00 of 4 bytes by task 16620 on cpu 1:
dentry_unlist fs/dcache.c:639 [inline]
__dentry_kill+0x2aa/0x4b0 fs/dcache.c:683
dput+0x5e/0xd0 fs/dcache.c:911
proc_invalidate_siblings_dcache+0x1c8/0x2a0 fs/proc/inode.c:143
proc_flush_pid+0x1d/0x30 fs/proc/base.c:3484
release_task+0x992/0xb60 kernel/exit.c:292
exit_notify kernel/exit.c:782 [inline]
do_exit+0xd85/0x1590 kernel/exit.c:975
do_group_exit+0xff/0x140 kernel/exit.c:1104
get_signal+0xe59/0xf70 kernel/signal.c:3034
arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x7a/0x100 kernel/entry/common.c:111
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0014000c -> 0x0000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 16620 Comm: syz.4.17497 Tainted: G W 6.16.0-rc1-syzkaller-00157-g02adc1490e6d #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.