[moderation] [fs?] KCSAN: data-race in d_walk / shrink_dentry_list (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 00a7d39898c8 fs/pipe: add simpler helpers for common cases
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15cce4b7980000
kernel config: https://syzkaller.appspot.com/x/.config?x=523b0e2f15224775
dashboard link: https://syzkaller.appspot.com/bug?extid=a15a9e97deae95e587ca
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/a11207d15131/disk-00a7d398.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4d448cc75d14/vmlinux-00a7d398.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d235b8c356e7/bzImage-00a7d398.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a15a9e...@syzkaller.appspotmail.com

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

read-write to 0xffff88810f9eaf00 of 4 bytes by task 4829 on cpu 1:
d_shrink_del fs/dcache.c:489 [inline]
shrink_dentry_list+0x19f/0x3e0 fs/dcache.c:1114
shrink_dcache_parent+0x43/0x1b0
d_invalidate+0xa9/0x1c0 fs/dcache.c:1632
proc_invalidate_siblings_dcache+0x1db/0x2b0 fs/proc/inode.c:142
proc_flush_pid+0x1d/0x30 fs/proc/base.c:3491
release_task+0xb7f/0xc20 kernel/exit.c:279
exit_notify kernel/exit.c:775 [inline]
do_exit+0xf5d/0x17f0 kernel/exit.c:958
do_group_exit+0x102/0x150 kernel/exit.c:1087
get_signal+0xeb9/0x1000 kernel/signal.c:3036
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x62/0x120 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810f9eaf00 of 4 bytes by task 4235 on cpu 0:
d_walk+0x24a/0x4a0 fs/dcache.c:1290
shrink_dcache_parent+0x84/0x1b0 fs/dcache.c:1527
d_invalidate+0xa9/0x1c0 fs/dcache.c:1632
proc_invalidate_siblings_dcache+0x1db/0x2b0 fs/proc/inode.c:142
proc_flush_pid+0x1d/0x30 fs/proc/base.c:3491
release_task+0xad9/0xc20 kernel/exit.c:279
wait_task_zombie kernel/exit.c:1249 [inline]
wait_consider_task+0x116e/0x1680 kernel/exit.c:1476
do_wait_thread kernel/exit.c:1539 [inline]
__do_wait+0x100/0x500 kernel/exit.c:1657
do_wait+0xaf/0x270 kernel/exit.c:1691
kernel_wait4+0x164/0x1d0 kernel/exit.c:1850
__do_sys_wait4 kernel/exit.c:1878 [inline]
__se_sys_wait4 kernel/exit.c:1874 [inline]
__x64_sys_wait4+0x94/0x120 kernel/exit.c:1874
x64_sys_call+0x25a2/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:62
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0028044c -> 0x0000004c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4235 Comm: syz-executor Not tainted 6.14.0-rc5-syzkaller-00137-g00a7d39898c8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


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[syzbot]

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