INFO: task syz-executor.2:28528 blocked for more than 143 seconds. Not tainted 5.4.0-rc4+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28296 28528 7988 0x00004004 Call Trace: context_switch kernel/sched/core.c:3384 [inline] __schedule+0x74b/0xb80 kernel/sched/core.c:4069 schedule+0x131/0x1e0 kernel/sched/core.c:4136 schedule_timeout+0x46/0x240 kernel/time/timer.c:1871 do_wait_for_common+0x2e7/0x4d0 kernel/sched/completion.c:83 __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x47/0x60 kernel/sched/completion.c:136 flush_workqueue+0x60d/0x14b0 kernel/workqueue.c:2826 nbd_start_device_ioctl drivers/block/nbd.c:1272 [inline] __nbd_ioctl drivers/block/nbd.c:1347 [inline] nbd_ioctl+0x9d2/0xac0 drivers/block/nbd.c:1387 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0x807/0x2980 block/ioctl.c:606 block_ioctl+0xbd/0x100 fs/block_dev.c:1954 do_vfs_ioctl+0x744/0x1730 fs/ioctl.c:46 ksys_ioctl fs/ioctl.c:713 [inline] __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459ef9 Code: ff cd 03 48 8b 73 50 64 48 39 34 25 f8 ff ff ff 75 07 e8 9a 41 fd ff cd 03 48 8b 44 24 08 48 89 43 10 48 8d 44 24 10 48 89 43 <08> 64 48 8b 34 25 f8 ff ff ff 48 89 73 18 48 8b 04 24 48 89 46 40 RSP: 002b:00007fe443f7dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000459ef9 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe443f7e6d4 R13: 00000000004c3982 R14: 00000000004d7818 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1070: #0: ffffffff888d4040 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 1 lock held by rsyslogd/7859: #0: ffff8880a0719ae0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x243/0x2e0 fs/file.c:801 2 locks held by getty/7949: #0: ffff8880a9a5b090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f352e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7950: #0: ffff8880a3536090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f252e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7951: #0: ffff8880a8cbd090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f312e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7952: #0: ffff8880a9911090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f392e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7953: #0: ffff8880a9517090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f3d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7954: #0: ffff8880a9915090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f412e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/7955: #0: ffff888097619090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f112e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by kworker/u5:1/8359: #0: ffff88809ec9c528 ((wq_completion)knbd2-recv){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff88809ec9c528 ((wq_completion)knbd2-recv){+.+.}, at: process_one_work+0x75d/0x10e0 kernel/workqueue.c:2242 #1: ffff8880a377fd78 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x79f/0x10e0 kernel/workqueue.c:2244 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1070 Comm: khungtaskd Not tainted 5.4.0-rc4+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d8/0x2f8 lib/dump_stack.c:113 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace+0x17/0x20 include/linux/nmi.h:146 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xbb9/0xbd0 kernel/hung_task.c:289 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 7996 Comm: kworker/1:3 Not tainted 5.4.0-rc4+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_power_efficient gc_worker RIP: 0010:nf_conntrack_get_ht include/net/netfilter/nf_conntrack.h:300 [inline] RIP: 0010:gc_worker+0x1b5/0xf70 net/netfilter/nf_conntrack_core.c:1247 Code: 56 ce 35 88 e8 7c d4 44 fb 66 90 66 2e 0f 1f 84 00 00 00 00 00 48 8b 45 98 ff c0 48 89 45 98 eb 09 0f 1f 40 00 e8 6b 44 5f fb 46 55 ff ff 8b 1d 3c fc aa 02 4c 8b 35 29 fc aa 02 39 05 4b fc RSP: 0018:ffff8880605b7c28 EFLAGS: 00000213 RAX: 0000000000002db0 RBX: 0000000000000001 RCX: ffff8880605a8640 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880aeb35820 RBP: ffff8880605b7cd8 R08: dffffc0000000000 R09: ffffed1015d66b05 R10: ffffed1015d66b05 R11: 0000000000000000 R12: 0000000000005b5f R13: 0000000000000002 R14: ffff88809c000000 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001594740 CR3: 00000000932ae000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: process_one_work+0x7ef/0x10e0 kernel/workqueue.c:2269 worker_thread+0xc01/0x1630 kernel/workqueue.c:2415 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352