[moderation] [fs?] KCSAN: data-race in __dentry_kill / shrink_dentry_list (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4a5df3796467 Merge tag 'mm-hotfixes-stable-2024-11-16-15-3..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1666d378580000
kernel config: https://syzkaller.appspot.com/x/.config?x=cabab325c3b4f39f
dashboard link: https://syzkaller.appspot.com/bug?extid=835ae1cec160516001fd
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/d26b69f54e75/disk-4a5df379.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/990c619271f0/vmlinux-4a5df379.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e4b211063db3/bzImage-4a5df379.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+835ae1...@syzkaller.appspotmail.com

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

read-write to 0xffff888106242840 of 4 bytes by task 19825 on cpu 0:
d_shrink_del fs/dcache.c:461 [inline]
shrink_dentry_list+0x19f/0x3e0 fs/dcache.c:1086
shrink_dcache_parent+0x43/0x1b0
d_invalidate+0xa9/0x1c0 fs/dcache.c:1604
proc_invalidate_siblings_dcache+0x1db/0x2b0 fs/proc/inode.c:142
proc_flush_pid+0x1d/0x30 fs/proc/base.c:3477
release_task+0xad9/0xc20 kernel/exit.c:280
wait_task_zombie kernel/exit.c:1250 [inline]
wait_consider_task+0x116e/0x1680 kernel/exit.c:1477
do_wait_thread kernel/exit.c:1540 [inline]
__do_wait+0x100/0x500 kernel/exit.c:1658
do_wait+0xaf/0x270 kernel/exit.c:1692
kernel_wait4+0x164/0x1d0 kernel/exit.c:1851
__do_sys_wait4 kernel/exit.c:1879 [inline]
__se_sys_wait4 kernel/exit.c:1875 [inline]
__x64_sys_wait4+0x94/0x120 kernel/exit.c:1875
x64_sys_call+0x2529/0x2d60 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

read to 0xffff888106242840 of 4 bytes by task 27225 on cpu 1:
dentry_unlist fs/dcache.c:585 [inline]
__dentry_kill+0x2af/0x4c0 fs/dcache.c:629
dput+0x5c/0xd0 fs/dcache.c:857
proc_invalidate_siblings_dcache+0x1e3/0x2b0 fs/proc/inode.c:143
proc_flush_pid+0x1d/0x30 fs/proc/base.c:3477
release_task+0xb7f/0xc20 kernel/exit.c:280
exit_notify kernel/exit.c:776 [inline]
do_exit+0xf62/0x17f0 kernel/exit.c:959
do_group_exit+0x102/0x150 kernel/exit.c:1088
get_signal+0xf2a/0x1070 kernel/signal.c:2918
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:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0048040c -> 0x0000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 27225 Comm: syz.3.7623 Not tainted 6.12.0-rc7-syzkaller-00212-g4a5df3796467 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
==================================================================


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[syzbot]

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