INFO: task kworker/u4:0:8762 blocked for more than 143 seconds. Not tainted 5.11.0-rc4-next-20210121-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:0 state:D stack:24080 pid: 8762 ppid: 2 flags:0x00004000 Workqueue: events_unbound io_ring_exit_work Call Trace: context_switch kernel/sched/core.c:4373 [inline] __schedule+0x90c/0x21a0 kernel/sched/core.c:5124 schedule+0xcf/0x270 kernel/sched/core.c:5203 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+0x163/0x260 kernel/sched/completion.c:138 kthread_park+0x122/0x1b0 kernel/kthread.c:557 io_sq_thread_park fs/io_uring.c:7448 [inline] io_sq_thread_park fs/io_uring.c:7442 [inline] io_sq_thread_stop+0xfe/0x570 fs/io_uring.c:7466 io_finish_async fs/io_uring.c:7484 [inline] io_ring_ctx_free fs/io_uring.c:8670 [inline] io_ring_exit_work+0x62/0x6d0 fs/io_uring.c:8763 process_one_work+0x98d/0x15f0 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:296 Showing all locks held in the system: 2 locks held by kworker/u4:1/25: 1 lock held by khungtaskd/1665: #0: ffffffff8b370ea0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6326 1 lock held by systemd-udevd/4869: 1 lock held by in:imklog/8161: #0: ffff88801c01bc70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:947 2 locks held by syz-executor.3/8495: #0: ffff8880216a4d88 (&xt[i].mutex){+.+.}-{3:3}, at: xt_find_table_lock+0x41/0x540 net/netfilter/x_tables.c:1206 #1: ffffffff8b379a68 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline] #1: ffffffff8b379a68 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x4f5/0x610 kernel/rcu/tree_exp.h:836 2 locks held by syz-executor.5/8562: #0: ffff8880216a4308 (&xt[i].mutex){+.+.}-{3:3}, at: xt_find_table_lock+0x41/0x540 net/netfilter/x_tables.c:1206 #1: ffffffff8b379a68 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline] #1: ffffffff8b379a68 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x27e/0x610 kernel/rcu/tree_exp.h:836 3 locks held by kworker/u4:0/8762: #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+0x871/0x15f0 kernel/workqueue.c:2246 #1: ffffc90001e4fda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x15f0 kernel/workqueue.c:2250 #2: ffff888025bcb070 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_park fs/io_uring.c:7447 [inline] #2: ffff888025bcb070 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_park fs/io_uring.c:7442 [inline] #2: ffff888025bcb070 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_stop+0xd6/0x570 fs/io_uring.c:7466 3 locks held by kworker/u4:5/9860: 2 locks held by kworker/1:6/10182: #0: ffff88801007c538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff88801007c538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff88801007c538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff88801007c538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff88801007c538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff88801007c538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x871/0x15f0 kernel/workqueue.c:2246 #1: ffffc900019efda8 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x15f0 kernel/workqueue.c:2250 1 lock held by syz-executor.1/29677: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1665 Comm: khungtaskd Not tainted 5.11.0-rc4-next-20210121-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+0x3b1/0x4a0 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: 8475 Comm: syz-fuzzer Not tainted 5.11.0-rc4-next-20210121-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0033:0x41f870 Code: 0f b6 3b 49 89 cb 89 f1 41 89 fc d3 ef 49 83 fb 08 74 0a 0f ba e7 04 0f 83 c2 00 00 00 41 0f a3 cc 73 b8 4b 8d 3c 0b 48 8b 3f <48> 85 ff 74 ac 49 89 fc 4c 29 cf 48 39 d7 72 a1 48 89 5c 24 78 4c RSP: 002b:000000c000039ea8 EFLAGS: 00000247 RAX: 0000000000203006 RBX: 00007fe508cef648 RCX: 0000000000000001 RDX: 0000000000000080 RSI: 0000000000000001 RDI: 000000c01176add0 RBP: 000000c000039f28 R08: 00007fe508e42fff R09: 000000c01958c900 R10: 000000c00001fe98 R11: 0000000000000008 R12: 00000000000000da R13: 000000c000000f00 R14: 000000bedb88fc81 R15: 0000000000000000 FS: 000000c00002e790 GS: 0000000000000000