INFO: task syz-executor.4:20327 blocked for more than 143 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D27232 20327 8226 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x837/0xc50 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 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+0x74d/0x1800 kernel/workqueue.c:2827 nbd_start_device_ioctl drivers/block/nbd.c:1301 [inline] __nbd_ioctl drivers/block/nbd.c:1376 [inline] nbd_ioctl+0x9d2/0xac0 drivers/block/nbd.c:1416 __blkdev_driver_ioctl block/ioctl.c:277 [inline] blkdev_ioctl+0x7f4/0x2ac0 block/ioctl.c:582 block_ioctl+0xbd/0x100 fs/block_dev.c:1983 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:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a679 Code: f3 a4 48 8b 94 24 18 10 00 00 ff 12 48 8b 94 24 10 10 00 00 48 8b bc 24 20 10 00 00 8b 8c 24 28 10 00 00 8b 9c 24 2c 10 00 00 <48> 89 e6 48 01 df 48 01 de 48 29 d9 e8 c6 fa ff ff 48 8b ac 24 00 RSP: 002b:00007f66caedac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 000000000045a679 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f66caedb6d4 R13: 00000000004c4270 R14: 00000000004d8d08 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1101: #0: ffffffff890d4bc0 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 2 locks held by kworker/u5:0/1583: #0: ffff8880917e5d28 ((wq_completion)knbd4-recv){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff8880917e5d28 ((wq_completion)knbd4-recv){+.+.}, at: process_one_work+0x75d/0x10d0 kernel/workqueue.c:2237 #1: ffff8880a5f47d78 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x79f/0x10d0 kernel/workqueue.c:2239 1 lock held by rsyslogd/8085: 2 locks held by getty/8175: #0: ffff8880a4064090 (&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/8176: #0: ffff888095014090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f552e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/8177: #0: ffff8880971c4090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f592e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/8178: #0: ffff8880944e2090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f452e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/8179: #0: ffff88809a1d4090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f512e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/8180: #0: ffff8880a9680090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f5d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 2 locks held by getty/8181: #0: ffff8880a7c6c090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: ffffc90005f2d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x221/0x1b00 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1101 Comm: khungtaskd Not tainted 5.4.0-syzkaller #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+0x1fb/0x318 lib/dump_stack.c:118 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+0xd49/0xd60 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: 9101 Comm: kworker/u4:13 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:747 [inline] RIP: 0010:arch_local_irq_save arch/x86/include/asm/paravirt.h:769 [inline] RIP: 0010:__local_bh_disable_ip+0x3c/0x170 kernel/softirq.c:116 Code: 05 85 3a b8 7e a9 00 00 0f 00 0f 85 39 01 00 00 48 c7 c0 20 96 0a 89 48 c1 e8 03 49 bc 00 00 00 00 00 fc ff df 42 80 3c 20 00 <74> 0c 48 c7 c7 20 96 0a 89 e8 06 af 67 00 48 83 3d 9e b2 c0 07 00 RSP: 0018:ffff88804d2c7b90 EFLAGS: 00000246 RAX: 1ffffffff12152c4 RBX: 0000000000000201 RCX: 1ffff11014efa3a1 RDX: 0000000000000000 RSI: 0000000000000201 RDI: ffffffff87c51fd9 RBP: ffff88804d2c7bb0 R08: ffff8880550c2d98 R09: fffffbfff13c7f33 R10: fffffbfff13c7f33 R11: 0000000000000000 R12: dffffc0000000000 R13: ffffffff87c52330 R14: ffffffff87c51fd9 R15: ffff88808d536000 FS: 0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c43949c370 CR3: 00000000a727f000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_bh include/linux/spinlock_api_smp.h:134 [inline] _raw_spin_lock_bh+0x1b/0x50 kernel/locking/spinlock.c:175 spin_lock_bh include/linux/spinlock.h:343 [inline] batadv_nc_purge_paths+0xe9/0x440 net/batman-adv/network-coding.c:441 batadv_nc_worker+0x30e/0x600 net/batman-adv/network-coding.c:719 process_one_work+0x7ef/0x10d0 kernel/workqueue.c:2264 worker_thread+0xc01/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352