======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:6/4301 is trying to acquire lock:
ffff8880212b7830 (kn->active#495){++++}-{0:0}, at: kernfs_remove+0x1d/0x30 fs/kernfs/dir.c:1406

but task is already holding lock:
ffffc9000314fd00 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}:
       process_one_work+0x7ba/0xff0 kernel/workqueue.c:2286
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #3 ((wq_completion)md_misc){+.+.}-{0:0}:
       flush_workqueue+0x16a/0x1390 kernel/workqueue.c:2830
       md_alloc+0x2e/0xc10 drivers/md/md.c:5727
       blk_probe_dev block/genhd.c:692 [inline]
       blk_request_module+0x26e/0x290 block/genhd.c:-1
       blkdev_get_no_open+0x38/0x1d0 block/bdev.c:736
       blkdev_get_by_dev+0x77/0xa50 block/bdev.c:803
       blkdev_open+0x128/0x2c0 block/fops.c:466
       do_dentry_open+0x7f7/0xf90 fs/open.c:826
       do_open fs/namei.c:3659 [inline]
       path_openat+0x2718/0x2fb0 fs/namei.c:3793
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (major_names_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       blk_probe_dev block/genhd.c:689 [inline]
       blk_request_module+0x31/0x290 block/genhd.c:705
       blkdev_get_no_open+0x38/0x1d0 block/bdev.c:736
       blkdev_get_by_dev+0x77/0xa50 block/bdev.c:803
       lock_rdev drivers/md/md.c:2583 [inline]
       md_import_device+0x3e2/0x810 drivers/md/md.c:3781
       md_add_new_disk+0x3fa/0x1960 drivers/md/md.c:6797
       md_ioctl+0x236f/0x26f0 drivers/md/md.c:7777
       blkdev_ioctl+0x347/0x6f0 block/ioctl.c:604
       block_ioctl+0xac/0xf0 block/fops.c:496
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&mddev->reconfig_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_interruptible_nested+0x17/0x20 kernel/locking/mutex.c:765
       mddev_lock drivers/md/md.h:543 [inline]
       level_store+0xcc/0x1a00 drivers/md/md.c:3995
       md_attr_store+0xdd/0x130 drivers/md/md.c:5643
       kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2179 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x748/0xd70 fs/read_write.c:594
       ksys_write+0x153/0x260 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (kn->active#495){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625
       kernfs_drain fs/kernfs/dir.c:478 [inline]
       __kernfs_remove+0x5da/0xcb0 fs/kernfs/dir.c:1372
       kernfs_remove+0x1d/0x30 fs/kernfs/dir.c:1406
       __kobject_del+0xe0/0x2e0 lib/kobject.c:628
       kobject_del+0x41/0x60 lib/kobject.c:651
       mddev_delayed_delete+0x27/0x30 drivers/md/md.c:5685
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

other info that might help us debug this:

Chain exists of:
  kn->active#495 --> (wq_completion)md_misc --> (work_completion)(&mddev->del_work)

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((work_completion)(&mddev->del_work));
                               lock((wq_completion)md_misc);
                               lock((work_completion)(&mddev->del_work));
  lock(kn->active#495);

 *** DEADLOCK ***

2 locks held by kworker/0:6/4301:
 #0: ffff8880183cb538 ((wq_completion)md_misc){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000314fd00 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285

stack backtrace:
CPU: 0 PID: 4301 Comm: kworker/0:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: md_misc mddev_delayed_delete
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625
 kernfs_drain fs/kernfs/dir.c:478 [inline]
 __kernfs_remove+0x5da/0xcb0 fs/kernfs/dir.c:1372
 kernfs_remove+0x1d/0x30 fs/kernfs/dir.c:1406
 __kobject_del+0xe0/0x2e0 lib/kobject.c:628
 kobject_del+0x41/0x60 lib/kobject.c:651
 mddev_delayed_delete+0x27/0x30 drivers/md/md.c:5685
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>