INFO: task kworker/1:2:936 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:2     state:D stack:22456 pid:936   tgid:936   ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: events reg_todo
Call Trace:
 <TASK>
 __schedule+0x15dd/0x52d0
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7fe/0x1300
 reg_process_self_managed_hints+0x8f/0x190
 reg_todo+0x8fa/0xa50
 process_scheduled_works+0xb6e/0x18c0
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>
INFO: task kworker/1:5:5875 blocked for more than 152 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:5     state:R  running task     stack:23392 pid:5875  tgid:5875  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue:  0x0 (events_power_efficient)
Call Trace:
 <TASK>
 __schedule+0x15dd/0x52d0
 schedule+0x164/0x360
 worker_thread+0xc21/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/1:1/31:
1 lock held by khungtaskd/34:
 #0: ffffffff8e75e520 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
1 lock held by khugepaged/42:
1 lock held by klogd/5246:
1 lock held by udevd/5257:
1 lock held by dhcpcd/5552:
2 locks held by dhcpcd/5553:
2 locks held by getty/5634:
 #0: ffff8881145df0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000356e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0
3 locks held by sshd/5783:
1 lock held by syz-executor/5787:
3 locks held by udevd/5812:
1 lock held by syz-executor/5814:
1 lock held by syz-executor/7441:
3 locks held by udevd/7443:
3 locks held by syz.4.508/8035:
2 locks held by syz-executor/8048:
2 locks held by syz-executor/8056:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 34 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/0x300
 sys_info+0x135/0x170
 watchdog+0xfd9/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 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: 5783 Comm: sshd 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:rcu_is_watching+0x5a/0xb0
Code: f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 4c 2a 85 00 48 c7 c3 58 39 1d 93 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 <84> c0 75 34 8b 03 65 ff 0d d9 4a 71 11 74 11 83 e0 04 c1 e8 02 5b
RSP: 0018:ffffc900047c7470 EFLAGS: 00000806
RAX: 0000000000000000 RBX: ffff888121033958 RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8c27bee0 RDI: ffffffff8c27bea0
RBP: 0000000000000000 R08: ffffffff90119ab7 R09: 1ffffffff2023356
R10: dffffc0000000000 R11: fffffbfff2023357 R12: ffff8881d1124000
R13: ffff8881d1120000 R14: ffffffff8e1af790 R15: dffffc0000000000
FS:  00007ff1d9756800(0000) GS:ffff88818de60000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f254f957000 CR3: 000000010fda8000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 trace_irq_enable+0x3b/0x150
 trace_hardirqs_on+0x18/0x40
 _raw_spin_unlock_irqrestore+0x30/0x80
 debug_check_no_obj_freed+0x52e/0x550
 __free_frozen_pages+0x549/0xdb0
 __slab_free+0x263/0x2b0
 qlist_free_all+0x97/0x100
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_node_noprof+0x384/0x690
 __alloc_skb+0x1d0/0x7d0
 tcp_stream_alloc_skb+0x3f/0x580
 tcp_sendmsg_locked+0x1375/0x5490
 tcp_sendmsg+0x2f/0x50
 sock_write_iter+0x406/0x4f0
 vfs_write+0x61d/0xb90
 ksys_write+0x150/0x270
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff1d9316bf2
Code: 89 c7 48 89 44 24 08 e8 7b 34 fa ff 48 8b 44 24 08 48 83 c4 28 c3 c3 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 6f 48 8b 15 07 a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffe2dbf9cb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000000000c4 RCX: 00007ff1d9316bf2
RDX: 00000000000000c4 RSI: 00007ff1d96ed010 RDI: 0000000000000004
RBP: 000055a15ae9e0e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000055a1439daaa4
R13: 0000000000000138 R14: 000055a1439db3e8 R15: 00007ffe2dbf9d28
 </TASK>
