INFO: task syz-executor.2:18490 blocked for more than 143 seconds. Not tainted 5.5.0-rc6-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27960 18490 8929 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4081 schedule+0x188/0x210 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+0x751/0x1820 kernel/workqueue.c:2827 nbd_start_device_ioctl drivers/block/nbd.c:1301 [inline] __nbd_ioctl drivers/block/nbd.c:1376 [inline] nbd_ioctl+0x934/0xb10 drivers/block/nbd.c:1416 __blkdev_driver_ioctl block/ioctl.c:277 [inline] blkdev_ioctl+0x856/0x2a50 block/ioctl.c:582 block_ioctl+0xbd/0x100 fs/block_dev.c:1983 do_vfs_ioctl+0x6e2/0x19b0 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:749 [inline] __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:754 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b159 Code: 24 68 48 8b 42 10 48 89 44 24 40 48 8b 4a 08 48 89 4c 24 50 48 8d 15 56 a2 b6 01 48 89 14 24 e8 bd f6 fa ff 48 8b 44 24 50 48 <8b> 4c 24 40 84 00 48 83 f9 05 0f 83 5b 01 00 00 48 8d 14 49 48 8b RSP: 002b:00007f7ea6652c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f7ea66536d4 RCX: 000000000045b159 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003e0 R14: 00000000004c50d7 R15: 000000000075bf2c Showing all locks held in the system: 3 locks held by kworker/u4:1/21: #0: ffff8880aed36f98 (&rq->lock){-.-.}, at: newidle_balance+0x6bc/0xb40 kernel/sched/fair.c:10177 #1: ffffffff890d45c0 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 #2: ffff8880aed27098 (&base->lock){-.-.}, at: lock_timer_base kernel/time/timer.c:936 [inline] #2: ffff8880aed27098 (&base->lock){-.-.}, at: __mod_timer+0x1a1/0x1570 kernel/time/timer.c:1008 1 lock held by khungtaskd/1114: #0: ffffffff890d45c0 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 1 lock held by rsyslogd/8795: 2 locks held by getty/8885: #0: ffff88809d9cc090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000174b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8886: #0: ffff8880a27e9090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017db2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8887: #0: ffff888090f5c090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8888: #0: ffff8880a2073090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017cb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8889: #0: ffff88809dbd0090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017bb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8890: #0: ffff888092f0f090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000179b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8891: #0: ffff8880911c9090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900016fb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by kworker/u5:2/15055: #0: ffff888056049528 ((wq_completion)knbd2-recv){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff888056049528 ((wq_completion)knbd2-recv){+.+.}, at: process_one_work+0x763/0x10d0 kernel/workqueue.c:2237 #1: ffffc90017b57d78 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x7a5/0x10d0 kernel/workqueue.c:2239 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1114 Comm: khungtaskd Not tainted 5.5.0-rc6-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+0xaa/0x190 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x16f/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+0xd40/0xd60 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: 21 Comm: kworker/u4:1 Not tainted 5.5.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker RIP: 0010:separate_irq_context kernel/locking/lockdep.c:3619 [inline] RIP: 0010:__lock_acquire+0x7d1/0x1bc0 kernel/locking/lockdep.c:3938 Code: 8a 04 38 84 c0 0f 85 fb 0d 00 00 45 8b 75 00 4d 85 f6 74 4d 4b 8d 04 b6 49 8d 9c c7 90 08 00 00 48 89 d8 48 c1 e8 03 8a 04 38 <84> c0 0f 85 fc 0d 00 00 8b 1b 48 8b 44 24 10 8a 04 38 84 c0 0f 85 RSP: 0018:ffffc90000dd7a70 EFLAGS: 00000806 RAX: 1ffff110153fd900 RBX: ffff8880a9fece60 RCX: ffffffff815b72f1 RDX: 0000000000000000 RSI: 0000000000000008 RDI: dffffc0000000000 RBP: ffffc90000dd7bc8 R08: dffffc0000000000 R09: fffffbfff13cd11d R10: fffffbfff13cd11d R11: 0000000000000000 R12: 855b7db014769bcc R13: ffff8880a9fece10 R14: 0000000000000002 R15: ffff8880a9fec580 FS: 0000000000000000(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 000000009dc06000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: lock_acquire+0x154/0x250 kernel/locking/lockdep.c:4484 rcu_lock_acquire+0x2e/0x40 include/linux/rcupdate.h:208 rcu_read_lock include/linux/rcupdate.h:617 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:407 [inline] batadv_nc_worker+0xc7/0x5f0 net/batman-adv/network-coding.c:718 process_one_work+0x7f5/0x10d0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352