Message-ID: <0ed14bc0-136d-e6e2-971b-513099864083@gmail.com>
Date:   Wed, 7 Apr 2021 20:51:02 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     syzbot <syzbot+93f72b3885406bb09e0d@...kaller.appspotmail.com>,
        syzkaller-bugs@...glegroups.com
Cc:     axboe@...nel.dk, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [syzbot] INFO: task hung in io_ring_exit_work

On 05/04/2021 20:34, syzbot wrote:
> Hello,
> 
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> INFO: task hung in io_ring_exit_work

Let's see if it's due to quiesce somehow being screwed.

#syz test: https://github.com/isilence/linux.git syz_test

> 
> INFO: task kworker/u4:4:191 blocked for more than 143 seconds.
>       Not tainted 5.12.0-rc2-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:kworker/u4:4    state:D stack:26056 pid:  191 ppid:     2 flags:0x00004000
> Workqueue: events_unbound io_ring_exit_work
> Call Trace:
>  context_switch kernel/sched/core.c:4324 [inline]
>  __schedule+0x911/0x21b0 kernel/sched/core.c:5075
>  schedule+0xcf/0x270 kernel/sched/core.c:5154
>  schedule_timeout+0x1db/0x250 kernel/time/timer.c:1868
>  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+0x168/0x270 kernel/sched/completion.c:138
>  io_ring_exit_work+0x4e8/0x12d0 fs/io_uring.c:8596
>  process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
>  worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
>  kthread+0x3b1/0x4a0 kernel/kthread.c:292
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> 
> Showing all locks held in the system:
> 2 locks held by kworker/u4:0/9:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90000ce7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:1/25:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90000dffda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:2/39:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90000e5fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:3/131:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc900013cfda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:4/191:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc900013dfda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 1 lock held by khungtaskd/1624:
>  #0: ffffffff8b774760 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6327
> 2 locks held by kswapd0/2123:
> 2 locks held by kswapd1/2124:
> 1 lock held by systemd-journal/4822:
>  #0: ffffffff8b88ca40 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_acquire+0xf7/0x150 mm/page_alloc.c:4349
> 1 lock held by systemd-udevd/4829:
>  #0: ffffffff8b88ca40 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_acquire+0xf7/0x150 mm/page_alloc.c:4349
> 1 lock held by in:imklog/8115:
>  #0: ffff888011236af0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:961
> 4 locks held by rs:main Q:Reg/8116:
>  #0: ffff8880243de0f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:961
>  #1: ffff888021dd2460 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x12d/0x250 fs/read_write.c:658
>  #2: ffff888026f6f288 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:775 [inline]
>  #2: ffff888026f6f288 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: ext4_buffered_write_iter+0xb6/0x4d0 fs/ext4/file.c:263
>  #3: ffffffff8b88ca40 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_acquire+0xf7/0x150 mm/page_alloc.c:4349
> 2 locks held by kworker/u4:5/8379:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc900019efda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by syz-execprog/8776:
>  #0: ffff8880314eb510 (&ei->i_mmap_sem){++++}-{3:3}, at: ext4_filemap_fault+0x7f/0xc0 fs/ext4/inode.c:6193
>  #1: ffffffff8b88ca40 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_acquire+0xf7/0x150 mm/page_alloc.c:4349
> 2 locks held by syz-execprog/8787:
>  #0: ffff8880314eb510 (&ei->i_mmap_sem){++++}-{3:3}, at: ext4_filemap_fault+0x7f/0xc0 fs/ext4/inode.c:6193
>  #1: ffff8880b9f35198 (&rq->lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1321 [inline]
>  #1: ffff8880b9f35198 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x21c/0x21b0 kernel/sched/core.c:4992
> 2 locks held by syz-executor.2/8797:
> 2 locks held by syz-executor.1/8798:
>  #0: ffff8881471ec308 (&xt[i].mutex){+.+.}-{3:3}, at: xt_find_table_lock+0x41/0x540 net/netfilter/x_tables.c:1206
>  #1: ffffffff8b88ca40 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_acquire+0xf7/0x150 mm/page_alloc.c:4349
> 2 locks held by syz-executor.5/8799:
> 1 lock held by syz-executor.0/8802:
>  #0: ffff8881471ec308 (&xt[i].mutex){+.+.}-{3:3}, at: xt_find_table_lock+0x41/0x540 net/netfilter/x_tables.c:1206
> 2 locks held by syz-executor.3/8804:
>  #0: ffff8881471ec458 (&xt[i].mutex){+.+.}-{3:3}, at: xt_find_table_lock+0x41/0x540 net/netfilter/x_tables.c:1206
>  #1: ffffffff8b77d328 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
>  #1: ffffffff8b77d328 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x27e/0x620 kernel/rcu/tree_exp.h:836
> 2 locks held by syz-executor.4/8805:
>  #0: ffff8881471ecd88 (&xt[i].mutex){+.+.}-{3:3}, at: xt_find_table_lock+0x41/0x540 net/netfilter/x_tables.c:1206
>  #1: ffffffff8b77d328 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
>  #1: ffffffff8b77d328 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x4fa/0x620 kernel/rcu/tree_exp.h:836
> 4 locks held by kworker/0:7/10089:
>  #0: ffff8880b9e35198 (&rq->lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1321 [inline]
>  #0: ffff8880b9e35198 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x21c/0x21b0 kernel/sched/core.c:4992
>  #1: ffff8880b9e1f948 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x305/0x440 kernel/sched/psi.c:833
>  #2: ffff8880b9e23ff0 (krc.lock){..-.}-{2:2}, at: kfree_rcu_monitor+0x15/0x80 kernel/rcu/tree.c:3438
>  #3: ffffffff8b840dc8 (jump_label_mutex){+.+.}-{3:3}, at: jump_label_lock kernel/jump_label.c:27 [inline]
>  #3: ffffffff8b840dc8 (jump_label_mutex){+.+.}-{3:3}, at: static_key_enable_cpuslocked+0xb1/0x260 kernel/jump_label.c:174
> 2 locks held by kworker/u4:6/10223:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000aa77da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:7/10807:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000c1d7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:8/11226:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000d127da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:9/11554:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000dcf7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:10/11577:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000dae7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:11/11579:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000db37da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:12/11689:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000e1a7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:13/11810:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000e117da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:14/11824:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000e6a7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:15/12398:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc900024e7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:16/12531:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90002d9fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:17/12594:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000301fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:18/12705:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc900033ffda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:19/13076:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90009c4fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:20/13178:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90009fffda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:21/13300:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000a45fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:22/14020:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000e2b7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:23/14264:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000f467da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:24/14300:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000f587da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:25/14307:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000eb77da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:26/14338:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000f727da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:27/14777:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90010767da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:28/14920:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90010ca7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:29/15364:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90011987da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:30/15519:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90002727da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:31/15546:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc900029cfda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:33/16097:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000c5e7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:34/16243:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000d257da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:35/16366:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000f507da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:36/16427:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc9000fad7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:37/16550:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90010507da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:38/16567:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90010717da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:40/16811:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90011ef7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:41/16844:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc90012067da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 2 locks held by kworker/u4:43/17310:
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
>  #0: ffff88800fc69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
>  #1: ffffc900130b7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
> 4 locks held by kworker/u4:46/17799:
> 
> =============================================
> 
> NMI backtrace for cpu 1
> CPU: 1 PID: 1624 Comm: khungtaskd Not tainted 5.12.0-rc2-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+0x141/0x1d7 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:146 [inline]
>  check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline]
>  watchdog+0xd48/0xfb0 kernel/hung_task.c:294
>  kthread+0x3b1/0x4a0 kernel/kthread.c:292
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> Sending NMI from CPU 1 to CPUs 0:
> NMI backtrace for cpu 0
> CPU: 0 PID: 2124 Comm: kswapd1 Not tainted 5.12.0-rc2-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:check_kcov_mode kernel/kcov.c:163 [inline]
> RIP: 0010:__sanitizer_cov_trace_pc+0x1c/0x60 kernel/kcov.c:197
> Code: 45 00 48 63 c9 e9 64 ff ff ff 0f 1f 40 00 65 8b 05 e9 11 8e 7e 89 c1 48 8b 34 24 81 e1 00 01 00 00 65 48 8b 14 25 00 f0 01 00 <a9> 00 01 ff 00 74 0e 85 c9 74 35 8b 82 2c 15 00 00 85 c0 74 2b 8b
> RSP: 0000:ffffc90007c671d0 EFLAGS: 00000246
> RAX: 0000000080000000 RBX: ffffc90007c672b0 RCX: 0000000000000000
> RDX: ffff888016ce1c40 RSI: ffffffff81aaf58b RDI: 0000000000000003
> RBP: ffff88803dbe6368 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffffff81aaf57d R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000000 R14: 000000003dbe6067 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000004054ef CR3: 000000000b48e000 CR4: 00000000001506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  map_pte mm/page_vma_mapped.c:20 [inline]
>  page_vma_mapped_walk+0x95b/0x2180 mm/page_vma_mapped.c:217
>  page_referenced_one+0x1b0/0x650 mm/rmap.c:785
>  rmap_walk_file+0x567/0xca0 mm/rmap.c:1936
>  rmap_walk+0x105/0x190 mm/rmap.c:1954
>  page_referenced+0x3c6/0x4b0 mm/rmap.c:895
>  page_check_references mm/vmscan.c:991 [inline]
>  shrink_page_list+0x291a/0x6420 mm/vmscan.c:1220
>  shrink_inactive_list+0x347/0xca0 mm/vmscan.c:1948
>  shrink_list mm/vmscan.c:2170 [inline]
>  shrink_lruvec+0x7f9/0x14f0 mm/vmscan.c:2465
>  shrink_node_memcgs mm/vmscan.c:2653 [inline]
>  shrink_node+0x868/0x1de0 mm/vmscan.c:2770
>  kswapd_shrink_node mm/vmscan.c:3513 [inline]
>  balance_pgdat+0x745/0x1270 mm/vmscan.c:3671
>  kswapd+0x5b6/0xdb0 mm/vmscan.c:3928
>  kthread+0x3b1/0x4a0 kernel/kthread.c:292
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> 
> 
> Tested on:
> 
> commit:         65f66804 io-wq: cancel unbounded
> git tree:       https://github.com/isilence/linux.git iowq_cancel_unbounded
> console output: https://syzkaller.appspot.com/x/log.txt?x=135f3cfcd00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=86318203e865a02b
> dashboard link: https://syzkaller.appspot.com/bug?extid=93f72b3885406bb09e0d
> compiler:       
> 

-- 
Pavel Begunkov

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