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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2c71fdf02a95 Merge tag 'drm-fixes-2024-04-09' of https://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12476339180000
kernel config: https://syzkaller.appspot.com/x/.config?x=6a1ac6d65bf295c5
dashboard link: https://syzkaller.appspot.com/bug?extid=3dcfcdecdea7c8055045
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/e3003de62f37/disk-2c71fdf0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/917e8f9f296d/vmlinux-2c71fdf0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b16ac69fc483/bzImage-2c71fdf0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3dcfcd...@syzkaller.appspotmail.com

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

write to 0xffff88811b42da80 of 4 bytes by task 3454 on cpu 0:
d_lru_del fs/dcache.c:437 [inline]
__dentry_kill+0xa0/0x4b0 fs/dcache.c:598
dput+0x5c/0xd0 fs/dcache.c:845
__fput+0x44c/0x660 fs/file_table.c:430
____fput+0x15/0x20 fs/file_table.c:450
task_work_run+0x13a/0x1a0 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x5fd/0x1740 kernel/exit.c:878
do_group_exit+0x102/0x150 kernel/exit.c:1027
get_signal+0xf2f/0x1080 kernel/signal.c:2911
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
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+0xda/0x1d0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b42da80 of 4 bytes by task 3449 on cpu 1:
dentry_unlist fs/dcache.c:573 [inline]
__dentry_kill+0x2a9/0x4b0 fs/dcache.c:617
shrink_kill fs/dcache.c:1048 [inline]
shrink_dentry_list+0x1bc/0x3e0 fs/dcache.c:1075
shrink_dcache_parent+0x43/0x1b0
vfs_rmdir+0x28d/0x300 fs/namei.c:4210
do_rmdir+0x194/0x320 fs/namei.c:4265
__do_sys_unlinkat fs/namei.c:4441 [inline]
__se_sys_unlinkat fs/namei.c:4435 [inline]
__x64_sys_unlinkat+0xa4/0xb0 fs/namei.c:4435
x64_sys_call+0x767/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:264
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+0x77/0x7f

value changed: 0x00280100 -> 0x00000100

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3449 Comm: syz-fuzzer Tainted: G W 6.9.0-rc3-syzkaller-00023-g2c71fdf02a95 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================


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