INFO: task kworker/u4:3:153 blocked for more than 143 seconds.
      Not tainted 5.10.0-rc4-next-20201119-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:3    state:D stack:26048 pid:  153 ppid:     2 flags:0x00004000
Workqueue: events_unbound io_ring_exit_work
Call Trace:
 context_switch kernel/sched/core.c:4269 [inline]
 __schedule+0x890/0x2030 kernel/sched/core.c:5019
 schedule+0xcf/0x270 kernel/sched/core.c:5098
 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1847
 do_wait_for_common kernel/sched/completion.c:85 [inline]
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x163/0x260 kernel/sched/completion.c:138
 kthread_stop+0x17a/0x720 kernel/kthread.c:596
 io_put_sq_data fs/io_uring.c:7242 [inline]
 io_sq_thread_stop+0x452/0x570 fs/io_uring.c:7339
 io_finish_async fs/io_uring.c:7346 [inline]
 io_ring_ctx_free fs/io_uring.c:8501 [inline]
 io_ring_exit_work+0x102/0x7a0 fs/io_uring.c:8595
 process_one_work+0x933/0x15a0 kernel/workqueue.c:2272
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418
 kthread+0x3af/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Showing all locks held in the system:
2 locks held by kworker/u4:3/153:
 #0: ffff888010069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff888010069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff888010069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff888010069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff888010069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff888010069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x821/0x15a0 kernel/workqueue.c:2243
 #1: ffffc9000150fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x854/0x15a0 kernel/workqueue.c:2247
1 lock held by khungtaskd/1655:
 #0: ffffffff8b339ca0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6252

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

NMI backtrace for cpu 1
CPU: 1 PID: 1655 Comm: khungtaskd Not tainted 5.10.0-rc4-next-20201119-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
 watchdog+0xd89/0xf30 kernel/hung_task.c:338
 kthread+0x3af/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 203 Comm: kworker/u4:4 Not tainted 5.10.0-rc4-next-20201119-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
RIP: 0010:arch_irqs_disabled_flags arch/x86/include/asm/irqflags.h:164 [inline]
RIP: 0010:check_preemption_disabled+0x4d/0x130 lib/smp_processor_id.c:19
Code: e3 ff ff ff 7f 31 ff 89 de 0f 1f 44 00 00 85 db 74 11 0f 1f 44 00 00 44 89 e0 5b 5d 41 5c 41 5d 41 5e c3 0f 1f 44 00 00 9c 5b <81> e3 00 02 00 00 31 ff 48 89 de 0f 1f 44 00 00 48 85 db 74 d3 0f
RSP: 0018:ffffc9000181fb98 EFLAGS: 00000046
RAX: 0000000000000007 RBX: 0000000000000046 RCX: 1ffffffff19dae13
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff899dfea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff894b6c40 R14: ffff8880119c4f80 R15: 000000000000016e
FS:  0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5b1636f000 CR3: 00000000132dd000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 lockdep_recursion_inc kernel/locking/lockdep.c:430 [inline]
 lock_release+0x15a/0x710 kernel/locking/lockdep.c:5454
 rcu_lock_release include/linux/rcupdate.h:260 [inline]
 rcu_read_unlock include/linux/rcupdate.h:698 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:411 [inline]
 batadv_nc_worker+0x7a3/0xe50 net/batman-adv/network-coding.c:718
 process_one_work+0x933/0x15a0 kernel/workqueue.c:2272
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418
 kthread+0x3af/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296