[moderation] [kernfs?] KCSAN: data-race in cleanup_glue_dir / kernfs_unlink_sibling (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6bd9ed02871f Merge tag 'cgroup-for-6.19-rc8-fixes' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1023cf2a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8e27f4588a0f2183
dashboard link: https://syzkaller.appspot.com/bug?extid=9827d14cf40b8c1e9c0d
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [gre...@linuxfoundation.org linux-...@vger.kernel.org t...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6a1f7a7be5a5/disk-6bd9ed02.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/92bf3a49bfa4/vmlinux-6bd9ed02.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1f9b3226a653/bzImage-6bd9ed02.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9827d1...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in cleanup_glue_dir / kernfs_unlink_sibling

read-write to 0xffff8881481887b0 of 8 bytes by task 19064 on cpu 0:
kernfs_unlink_sibling+0xbb/0x160 fs/kernfs/dir.c:426
__kernfs_remove+0x3a4/0x4c0 fs/kernfs/dir.c:1519
kernfs_remove+0x58/0x70 fs/kernfs/dir.c:1555
sysfs_remove_dir+0x7d/0xa0 fs/sysfs/dir.c:101
__kobject_del+0x97/0x190 lib/kobject.c:604
kobject_del+0x2e/0x50 lib/kobject.c:627
device_del+0x724/0x790 drivers/base/core.c:3898
device_unregister+0x15/0x40 drivers/base/core.c:3919
wakeup_source_sysfs_remove+0x25/0x30 drivers/base/power/wakeup_stats.c:210
wakeup_source_unregister+0xdf/0x330 drivers/base/power/wakeup.c:239
ep_free fs/eventpoll.c:821 [inline]
ep_clear_and_put+0x2d5/0x320 fs/eventpoll.c:937
ep_eventpoll_release+0x2c/0x40 fs/eventpoll.c:966
__fput+0x29b/0x650 fs/file_table.c:468
____fput+0x1c/0x30 fs/file_table.c:496
task_work_run+0x130/0x1a0 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x466/0x1590 kernel/exit.c:971
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

read to 0xffff8881481887b0 of 8 bytes by task 19063 on cpu 1:
kobject_has_children drivers/base/core.c:3347 [inline]
cleanup_glue_dir+0xe9/0x170 drivers/base/core.c:3413
device_del+0x72f/0x790 drivers/base/core.c:3899
device_unregister+0x15/0x40 drivers/base/core.c:3919
wakeup_source_sysfs_remove+0x25/0x30 drivers/base/power/wakeup_stats.c:210
wakeup_source_unregister+0xdf/0x330 drivers/base/power/wakeup.c:239
ep_free fs/eventpoll.c:821 [inline]
ep_clear_and_put+0x2d5/0x320 fs/eventpoll.c:937
ep_eventpoll_release+0x2c/0x40 fs/eventpoll.c:966
__fput+0x29b/0x650 fs/file_table.c:468
____fput+0x1c/0x30 fs/file_table.c:496
task_work_run+0x130/0x1a0 kernel/task_work.c:233
get_signal+0xe09/0xf60 kernel/signal.c:2807
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: 0x0000000000000001 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 19063 Comm: syz.4.5363 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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