------------[ cut here ]------------
timer_delete_sync(&sdp->delay_work) && rcu_segcblist_n_cbs(&sdp->srcu_cblist)
WARNING: kernel/rcu/srcutree.c:707 at cleanup_srcu_struct+0x3d6/0x8b0, CPU#1: kworker/u10:18/10241
Modules linked in:
CPU: 1 UID: 0 PID: 10241 Comm: kworker/u10:18 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
Workqueue: nbd-del nbd_dev_remove_work
RIP: 0010:cleanup_srcu_struct+0x3d6/0x8b0
Code: 3e 91 00 48 83 7d 00 00 4c 8b 74 24 10 0f 85 dd 03 00 00 41 ff c5 41 83 e5 0f 41 83 fd 07 0f 86 e2 fe ff ff e9 ab 00 00 00 90 <0f> 0b 90 4c 8d b5 00 02 00 00 4c 89 f3 48 c1 eb 03 48 b8 00 00 00
RSP: 0018:ffffc90003aff9d0 EFLAGS: 00010202
RAX: 1ffffd1fdc893c6d RBX: 0000607d57ff3280 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: ffffffff8e46eac5 RDI: 00000000ffffffff
RBP: ffffe8fee449e280 R08: ffffffff917ac47f R09: 1ffffffff22f588f
R10: dffffc0000000000 R11: fffffbfff22f5890 R12: ffff88816980d800
R13: 0000000000000000 R14: ffffe8fee449e368 R15: 1ffffffff1ce83de
FS:  0000000000000000(0000) GS:ffff8882a7cab000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31c17ff8 CR3: 00000001bf500000 CR4: 00000000000006f0
DR0: 0000200000000d40 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 blk_mq_free_tag_set+0x617/0x790
 nbd_dev_remove_work+0x4f/0xe0
 process_scheduled_works+0xc3d/0x1630
 worker_thread+0xa47/0xfb0
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
