------------[ cut here ]------------
!work->func
WARNING: kernel/workqueue.c:4288 at __flush_work+0xb8f/0xca0, CPU#0: syz-executor/5589
Modules linked in:
CPU: 0 UID: 0 PID: 5589 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__flush_work+0xb8f/0xca0
Code: 75 5e 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d e9 96 5c 24 0a cc e8 00 c0 37 00 90 0f 0b 90 e9 7c ff ff ff e8 f2 bf 37 00 90 <0f> 0b 90 31 c0 48 bb f8 f8 f8 f8 f8 f8 f8 f8 e9 64 ff ff ff e8 d8
RSP: 0018:ffffc9000646fb40 EFLAGS: 00010293
RAX: ffffffff818d3ede RBX: ffff88810daa12e8 RCX: ffff888112ad1d80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88810daa12d0
RBP: ffffc9000646fcf8 R08: ffffffff901188f7 R09: 1ffffffff202311e
R10: dffffc0000000000 R11: fffffbfff202311f R12: dffffc0000000000
R13: 1ffff11021b5425d R14: 1ffff92000c8df70 R15: ffff88810daa12d0
FS:  000055558ceef500(0000) GS:ffff88818de52000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558cf0aa28 CR3: 00000001174a0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __cancel_work_sync+0xbe/0x110
 ffs_fs_kill_sb+0x22f/0x370
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x3d3/0x460
 task_work_run+0x1d9/0x270
 exit_to_user_mode_loop+0x18d/0x5e0
 do_syscall_64+0x357/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc893f9f257
Code: a2 c7 05 9c 44 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe48845788 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fc89403445c RCX: 00007fc893f9f257
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe48845840
RBP: 00007ffe48845840 R08: 00007ffe48846840 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe488468d0
R13: 00007fc89403445c R14: 00000000000108f4 R15: 00007ffe48846910
 </TASK>
