INFO: task kworker/1:1H:99 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:1H    state:D stack:25656 pid:99    tgid:99    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: kblockd blk_mq_requeue_work
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_timeout+0x152/0x2c0
 nbd_queue_rq+0x889/0x1150
 blk_mq_dispatch_rq_list+0x499/0x1990
 __blk_mq_sched_dispatch_requests+0xd36/0x1580
 blk_mq_sched_dispatch_requests+0xd7/0x190
 blk_mq_run_hw_queue+0x348/0x4f0
 blk_mq_run_hw_queues+0x268/0x3f0
 blk_mq_requeue_work+0x703/0x760
 process_scheduled_works+0xa8e/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:0/12:
 #0: ffff88810c510140 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90000117c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffffffff9002d500 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x116/0x15c0
1 lock held by khungtaskd/35:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
4 locks held by kworker/1:1H/99:
 #0: ffff888162284140 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900027c7c40 ((work_completion)(&(&q->requeue_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff88810f099418 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x31f/0x4f0
 #3: ffff888111ff0178 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc1/0x1150
2 locks held by getty/5435:
 #0: ffff88810cc7c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
1 lock held by udevd/11063:
 #0: ffff888112eb7350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
3 locks held by syz.1.4042/20965:
 #0: ffffffff9001e948 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4e2/0x720
 #1: ffffffff9002d500 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0xe5/0x9a0
 #2: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
3 locks held by syz.0.4045/20976:
 #0: ffffffff9001e948 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4e2/0x720
 #1: ffffffff9002d500 (rtnl_mutex){+.+.}-{4:4}, at: cfg802154_pernet_exit+0x18/0xc0
 #2: ffff88812103b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 35 Comm: khungtaskd 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
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7823 Comm: kworker/0:11 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: mld mld_ifc_work
RIP: 0010:__lock_acquire+0xcc2/0x2cf0
Code: 22 10 75 2c 49 89 ae 90 0b 00 00 41 8b 86 98 0b 00 00 ff c0 41 89 86 98 0b 00 00 83 f8 30 0f 83 7d 18 00 00 3b 05 46 c5 d1 12 <0f> 87 d0 18 00 00 bd 01 00 00 00 e9 d4 06 00 00 41 83 fe 03 bf 02
RSP: 0018:ffffc90000007758 EFLAGS: 00000087
RAX: 0000000000000007 RBX: 00000000574e9a6c RCX: 0000000000000000
RDX: 00000000abf0ee80 RSI: 000000008e519db2 RDI: ffff888101bc0000
RBP: 5e28035c574e9a6c R08: ffffffff8177827f R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: ffff888101bc0c90
R13: ffff888101bc0c90 R14: ffff888101bc0000 R15: 0000000000000006
FS:  0000000000000000(0000) GS:ffff88818d954000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdfa3e97440 CR3: 000000016bdc8000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 lock_acquire+0x106/0x350
 unwind_next_frame+0xac/0x2550
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x40/0x50
 __kasan_slab_free+0x5c/0x80
 kmem_cache_free+0x182/0x650
 rcu_core+0x78b/0x10a0
 handle_softirqs+0x225/0x840
 do_softirq+0x76/0xd0
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x130
 ip6t_do_table+0x13c4/0x15b0
 nf_hook_slow+0xc5/0x220
 NF_HOOK+0x399/0x4f0
 mld_sendpack+0x890/0xe10
 mld_ifc_work+0x842/0xd60
 process_scheduled_works+0xa8e/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
