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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4ea5af085908 Merge tag 'pm-6.17-rc8' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11f8ed34580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6e0c213d0735f5dd
dashboard link: https://syzkaller.appspot.com/bug?extid=dc219afe3f428b005692
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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/fab03e8e5e3f/disk-4ea5af08.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e12951599355/vmlinux-4ea5af08.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b3e1b3c59f98/bzImage-4ea5af08.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dc219a...@syzkaller.appspotmail.com

smc: removing ib device !yz!
==================================================================
BUG: KCSAN: data-race in cleanup_glue_dir / kernfs_unlink_sibling

read-write to 0xffff8881184081d8 of 8 bytes by task 51 on cpu 1:
kernfs_unlink_sibling+0xbb/0x160 fs/kernfs/dir.c:426
__kernfs_remove+0x1c7/0x2e0 fs/kernfs/dir.c:1514
kernfs_remove+0x58/0x70 fs/kernfs/dir.c:1550
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+0x725/0x790 drivers/base/core.c:3898
cdev_device_del+0x1b/0x90 fs/char_dev.c:580
ib_umad_kill_port+0xad/0x210 drivers/infiniband/core/user_mad.c:1355
ib_umad_remove_one+0x10e/0x190 drivers/infiniband/core/user_mad.c:1443
remove_client_context+0x9f/0x1a0 drivers/infiniband/core/device.c:812
disable_device+0xca/0x260 drivers/infiniband/core/device.c:1318
__ib_unregister_device+0x1fb/0x2d0 drivers/infiniband/core/device.c:1555
ib_unregister_work+0x19/0x30 drivers/infiniband/core/device.c:1667
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
worker_thread+0x582/0x770 kernel/workqueue.c:3400
kthread+0x489/0x510 kernel/kthread.c:463
ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff8881184081d8 of 8 bytes by task 10141 on cpu 0:
kobject_has_children drivers/base/core.c:3347 [inline]
cleanup_glue_dir+0xe9/0x170 drivers/base/core.c:3413
device_del+0x730/0x790 drivers/base/core.c:3899
cdev_device_del+0x1b/0x90 fs/char_dev.c:580
ib_umad_kill_port+0xad/0x210 drivers/infiniband/core/user_mad.c:1355
ib_umad_remove_one+0x10e/0x190 drivers/infiniband/core/user_mad.c:1443
remove_client_context+0x9f/0x1a0 drivers/infiniband/core/device.c:812
disable_device+0xca/0x260 drivers/infiniband/core/device.c:1318
__ib_unregister_device+0x1fb/0x2d0 drivers/infiniband/core/device.c:1555
ib_unregister_work+0x19/0x30 drivers/infiniband/core/device.c:1667
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
worker_thread+0x582/0x770 kernel/workqueue.c:3400
kthread+0x489/0x510 kernel/kthread.c:463
ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000000000001 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10141 Comm: kworker/u8:61 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: ib-unreg-wq ib_unregister_work
==================================================================


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