INFO: task kworker/u4:5:226 blocked for more than 143 seconds. Not tainted 5.10.0-rc4-next-20201117-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:5 state:D stack:26704 pid: 226 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:7235 [inline] io_sq_thread_stop+0x452/0x570 fs/io_uring.c:7332 io_finish_async fs/io_uring.c:7339 [inline] io_ring_ctx_free fs/io_uring.c:8494 [inline] io_ring_exit_work+0x102/0x7a0 fs/io_uring.c:8588 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/u4:5/226: #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: ffffc900016cfda8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x854/0x15a0 kernel/workqueue.c:2247 1 lock held by khungtaskd/1623: #0: ffffffff8b339ca0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6252 1 lock held by systemd-udevd/4903: #0: ffff8880163a8d80 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_get+0x457/0x1870 fs/block_dev.c:1472 1 lock held by in:imklog/8192: #0: ffff88801d69c0f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:932 2 locks held by syz-executor.3/8513: #0: ffff8880163aa780 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_get+0x457/0x1870 fs/block_dev.c:1472 #1: ffffffff8bd23188 (loop_ctl_mutex){+.+.}-{3:3}, at: lo_open+0x19/0xd0 drivers/block/loop.c:1890 2 locks held by systemd-udevd/19945: #0: ffff888019a8ae00 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_put+0xfc/0x890 fs/block_dev.c:1762 #1: ffffffff8bd23188 (loop_ctl_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x88/0xe50 drivers/block/loop.c:1210 2 locks held by systemd-udevd/19992: #0: ffff888019a8a780 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_put+0xfc/0x890 fs/block_dev.c:1762 #1: ffffffff8bd23188 (loop_ctl_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x770/0xe50 drivers/block/loop.c:1295 2 locks held by systemd-udevd/20013: #0: ffff888019a88700 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_put+0xfc/0x890 fs/block_dev.c:1762 #1: ffffffff8bd23188 (loop_ctl_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x770/0xe50 drivers/block/loop.c:1295 2 locks held by systemd-udevd/20223: #0: ffff8880163aa100 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_put+0xfc/0x890 fs/block_dev.c:1762 #1: ffffffff8bd23188 (loop_ctl_mutex){+.+.}-{3:3}, at: lo_release+0x1a/0x1f0 drivers/block/loop.c:1909 1 lock held by syz-executor.4/4493: #0: ffff888019a8a780 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_get+0x457/0x1870 fs/block_dev.c:1472 2 locks held by syz-executor.1/4501: #0: ffff8880163a8d80 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_get+0x457/0x1870 fs/block_dev.c:1472 #1: ffffffff8bd23188 (loop_ctl_mutex){+.+.}-{3:3}, at: lo_open+0x19/0xd0 drivers/block/loop.c:1890 1 lock held by syz-executor.0/4497: #0: ffff8880b9e34f98 (&rq->lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1318 [inline] #0: ffff8880b9e34f98 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x217/0x2030 kernel/sched/core.c:4936 1 lock held by syz-executor.0/4500: #0: ffff888019a88700 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_get+0x457/0x1870 fs/block_dev.c:1472 1 lock held by syz-executor.2/4503: #0: ffff8880163aa100 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_get+0x457/0x1870 fs/block_dev.c:1472 1 lock held by syz-executor.5/4502: #0: ffff888019a8ae00 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_get+0x457/0x1870 fs/block_dev.c:1472 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1623 Comm: khungtaskd Not tainted 5.10.0-rc4-next-20201117-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: 9844 Comm: kworker/0:5 Not tainted 5.10.0-rc4-next-20201117-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events nsim_dev_trap_report_work RIP: 0010:lockdep_hardirqs_off+0x7d/0xd0 kernel/locking/lockdep.c:4181 Code: 48 c7 c6 80 68 4b 89 48 c7 c7 c0 68 4b 89 e8 5a fc c6 ff 0f 0b eb cc 48 c7 c7 20 6a 4b 89 e8 fa 0d 00 00 65 8b 05 43 5a 18 77 <85> c0 74 a0 5b 5d c3 48 c7 c7 e0 69 4b 89 e8 e0 0d 00 00 65 48 8b RSP: 0018:ffffc900167afad0 EFLAGS: 00000002 RAX: 0000000000000000 RBX: ffffffff88ec09fe RCX: 0000000000000001 RDX: ffff888023111a80 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffff8880101a9b48 R08: 0000000000000000 R09: ffffffff8ced410f R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000293 R13: ffffc900167afba8 R14: ffffc900167afba8 R15: ffff8880101a9b48 FS: 0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd092979000 CR3: 0000000027ba6000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: trace_hardirqs_off+0x13/0x1b0 kernel/trace/trace_preemptirq.c:76 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline] _raw_spin_lock_irqsave+0x4e/0x50 kernel/locking/spinlock.c:159 _extract_crng+0xd2/0x250 drivers/char/random.c:1007 extract_crng drivers/char/random.c:1026 [inline] _get_random_bytes+0x229/0x670 drivers/char/random.c:1562 eth_random_addr include/linux/etherdevice.h:225 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:518 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:568 [inline] nsim_dev_trap_report_work+0x34c/0xbd0 drivers/net/netdevsim/dev.c:609 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