WARNING in pwq_unbound_release_workfn

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    f6e1ea19 Merge tag 'ceph-for-5.11-rc2' of git://github.com..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=107ff5ff500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e5a71d05f90e097
dashboard link: https://syzkaller.appspot.com/bug?extid=01c96fb3fff96a6e571f
compiler:       gcc (GCC) 10.1.0-syz 20200507
userspace arch: i386

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+01c96fb3fff96a6e571f@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
WARNING: CPU: 3 PID: 9370 at kernel/locking/lockdep.c:6113 lockdep_unregister_key+0x191/0x230 kernel/locking/lockdep.c:6113
Modules linked in:
CPU: 3 PID: 9370 Comm: kworker/3:3 Not tainted 5.11.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Workqueue: events pwq_unbound_release_workfn
RIP: 0010:lockdep_unregister_key+0x191/0x230 kernel/locking/lockdep.c:6113
Code: b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 7a 4d 89 7d 08 48 b8 22 01 00 00 00 00 ad de 48 89 43 08 eb 02 <0f> 0b 4c 89 f7 ba 01 00 00 00 48 89 ee e8 4d fd ff ff 4c 89 f7 e8
RSP: 0018:ffffc9000335fca8 EFLAGS: 00010046
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffffffff19df003
RDX: 1ffffffff1dcf914 RSI: 0000000000000004 RDI: ffffffff8ee7c8a0
RBP: ffff888028461128 R08: 0000000000000001 R09: 0000000000000003
R10: fffff5200066bf8b R11: 000000000000014e R12: 0000000000000246
R13: dffffc0000000000 R14: ffffffff8ecf5768 R15: ffff888049fec470
FS:  0000000000000000(0000) GS:ffff88802cd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa82fa09000 CR3: 000000006bb17000 CR4: 0000000000350ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 wq_unregister_lockdep kernel/workqueue.c:3467 [inline]
 pwq_unbound_release_workfn+0x227/0x2d0 kernel/workqueue.c:3699
 process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296


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