INFO: task syz-executor.1:12779 blocked for more than 143 seconds. Not tainted 5.4.0-rc1+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28016 12779 8833 0x00004004 Call Trace: context_switch kernel/sched/core.c:3384 [inline] __schedule+0x94f/0x1e70 kernel/sched/core.c:4069 schedule+0xd9/0x260 kernel/sched/core.c:4136 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 flush_workqueue+0x40f/0x14c0 kernel/workqueue.c:2826 nbd_start_device_ioctl drivers/block/nbd.c:1272 [inline] __nbd_ioctl drivers/block/nbd.c:1347 [inline] nbd_ioctl+0xb2e/0xc44 drivers/block/nbd.c:1387 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0xedb/0x1c20 block/ioctl.c:606 block_ioctl+0xee/0x130 fs/block_dev.c:1954 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459a59 Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <90> 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00007f0c272cfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000459a59 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0c272d06d4 R13: 00000000004c337f R14: 00000000004d6f90 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1064: #0: ffffffff88faae00 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5337 1 lock held by rsyslogd/8702: 2 locks held by getty/8792: #0: ffff88808e0eca90 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f472e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8793: #0: ffff88808e0ed310 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f412e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8794: #0: ffff88808e0412d0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f392e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8795: #0: ffff88808e040a50 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f3d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8796: #0: ffff88808e60c190 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f352e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8797: #0: ffff88808e0401d0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f4b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8798: #0: ffff88808f29cf10 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f192e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by kworker/u5:3/10312: #0: ffff88809d39ade8 ((wq_completion)knbd1-recv){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff88809d39ade8 ((wq_completion)knbd1-recv){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff88809d39ade8 ((wq_completion)knbd1-recv){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff88809d39ade8 ((wq_completion)knbd1-recv){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff88809d39ade8 ((wq_completion)knbd1-recv){+.+.}, at: set_work_data kernel/workqueue.c:620 [inline] #0: ffff88809d39ade8 ((wq_completion)knbd1-recv){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline] #0: ffff88809d39ade8 ((wq_completion)knbd1-recv){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2240 #1: ffff88805971fdc0 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2244 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1064 Comm: khungtaskd Not tainted 5.4.0-rc1+ #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+0x172/0x1f0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0x9d0/0xef0 kernel/hung_task.c:289 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 85 Comm: kworker/u4:3 Not tainted 5.4.0-rc1+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:68 [inline] RIP: 0010:write_comp_data+0x9/0x70 kernel/kcov.c:123 Code: 13 00 00 8b 80 fc 12 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 5d c3 0f 1f 00 65 4c 8b 04 25 40 fe 01 00 <65> 8b 05 c8 ea 8e 7e a9 00 01 1f 00 75 51 41 8b 80 f8 12 00 00 83 RSP: 0018:ffff8880a94a7cc8 EFLAGS: 00000246 RAX: 0000000000000001 RBX: ffff88809e233000 RCX: ffffffff872ad0e1 RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000001 RBP: ffff8880a94a7cd0 R08: ffff8880a948e000 R09: ffffed1015d06b75 R10: ffffed1015d06b74 R11: ffff8880ae835ba3 R12: 0000000000000001 R13: 000000000000024e R14: 0000000000000001 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f60403ee7f6 CR3: 0000000091067000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_unlock include/linux/rcupdate.h:649 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:411 [inline] batadv_nc_worker+0x491/0x760 net/batman-adv/network-coding.c:718 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352