[moderation] [fs?] KCSAN: data-race in __dentry_kill / shrink_dentry_list (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f14faaf3a1fb Merge tag 'tsm-fixes-for-6.19' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=126c30aa580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8e27f4588a0f2183
dashboard link: https://syzkaller.appspot.com/bug?extid=d06052ebb0afe1ac78a8
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
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/9cdf3c60fee1/disk-f14faaf3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/24b163320d00/vmlinux-f14faaf3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/854533a48cfc/bzImage-f14faaf3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d06052...@syzkaller.appspotmail.com

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

read-write to 0xffff88811a56a9c0 of 4 bytes by task 3641 on cpu 1:
d_shrink_del fs/dcache.c:516 [inline]
shrink_dentry_list+0x1a6/0x3c0 fs/dcache.c:1173
shrink_dcache_tree+0x5b/0x220 fs/dcache.c:-1
shrink_dcache_parent fs/dcache.c:1626 [inline]
d_invalidate+0x76/0x1d0 fs/dcache.c:1708
proc_invalidate_siblings_dcache+0x1c8/0x2b0 fs/proc/inode.c:142
proc_flush_pid+0x1d/0x30 fs/proc/base.c:3478
release_task+0x988/0xb60 kernel/exit.c:291
wait_task_zombie kernel/exit.c:1274 [inline]
wait_consider_task+0x1160/0x1670 kernel/exit.c:1501
do_wait_thread kernel/exit.c:1564 [inline]
__do_wait+0xf9/0x510 kernel/exit.c:1682
do_wait+0xb6/0x240 kernel/exit.c:1716
kernel_wait4+0x19f/0x210 kernel/exit.c:1875
__do_sys_wait4 kernel/exit.c:1903 [inline]
__se_sys_wait4 kernel/exit.c:1899 [inline]
__x64_sys_wait4+0x91/0x120 kernel/exit.c:1899
x64_sys_call+0x28ec/0x3000 arch/x86/include/generated/asm/syscalls_64.h:62
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a56a9c0 of 4 bytes by task 3978 on cpu 0:
dentry_unlist fs/dcache.c:640 [inline]
__dentry_kill+0x25c/0x460 fs/dcache.c:684
finish_dput+0x2b/0x200 fs/dcache.c:879
dput+0x52/0x60 fs/dcache.c:928
proc_invalidate_siblings_dcache+0x1d0/0x2b0 fs/proc/inode.c:143
proc_flush_pid+0x1d/0x30 fs/proc/base.c:3478
release_task+0x988/0xb60 kernel/exit.c:291
exit_notify kernel/exit.c:777 [inline]
do_exit+0xd56/0x1590 kernel/exit.c:983
do_group_exit+0xfe/0x140 kernel/exit.c:1112
get_signal+0xe4f/0xf60 kernel/signal.c:3034
arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x1d3/0x2a0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0024040c -> 0x0000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3978 Comm: syz.5.150 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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