INFO: task kworker/u4:5:383 blocked for more than 143 seconds. Not tainted 5.6.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:5 D24776 383 2 0x80004000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:3386 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4082 schedule+0x188/0x210 kernel/sched/core.c:4156 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4215 __mutex_lock_common+0x11f1/0x2f30 kernel/locking/mutex.c:1033 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1b/0x30 kernel/locking/mutex.c:1118 flush_to_ldisc+0x39/0x550 drivers/tty/tty_buffer.c:505 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 process_scheduled_works kernel/workqueue.c:2326 [inline] worker_thread+0xe77/0x1630 kernel/workqueue.c:2415 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 INFO: task login:8767 blocked for more than 143 seconds. Not tainted 5.6.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D24088 8767 1 0x00004004 Call Trace: context_switch kernel/sched/core.c:3386 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4082 schedule+0x188/0x210 kernel/sched/core.c:4156 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_work+0xcf/0x130 kernel/workqueue.c:3041 flush_work+0x17/0x20 kernel/workqueue.c:3062 tty_buffer_flush_work+0x19/0x20 drivers/tty/tty_buffer.c:618 n_tty_read+0x6ce/0x1bc0 drivers/tty/n_tty.c:2199 tty_read+0x15f/0x310 drivers/tty/tty_io.c:869 __vfs_read+0xb8/0x730 fs/read_write.c:425 vfs_read+0x1d8/0x420 fs/read_write.c:461 ksys_read+0x117/0x220 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x7b/0x90 fs/read_write.c:595 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fd39b622310 Code: Bad RIP value. RSP: 002b:00007fff4f51c908 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd39b622310 RDX: 00000000000001ff RSI: 00007fff4f51cb70 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007fd39bf05700 R09: 0000000000000000 R10: 00007fff4f51c8c0 R11: 0000000000000246 R12: 00007fff4f51cb70 R13: 0000000000000000 R14: 0000000000000001 R15: 000000000060b798 Showing all locks held in the system: 3 locks held by kworker/u4:5/383: #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: process_one_work+0x763/0x10f0 kernel/workqueue.c:2237 #1: ffffc90002397d78 ((work_completion)(&buf->work)){+.+.}, at: process_one_work+0x7a5/0x10f0 kernel/workqueue.c:2239 #2: ffff8880a6ff40a8 (&buf->lock){+.+.}, at: flush_to_ldisc+0x39/0x550 drivers/tty/tty_buffer.c:505 1 lock held by khungtaskd/1092: #0: ffffffff892d98c8 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 1 lock held by rsyslogd/8674: #0: ffff888093cf6ba0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x279/0x310 fs/file.c:821 2 locks held by getty/8764: #0: ffff8880a74d9090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8765: #0: ffff88809f363090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000184b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8766: #0: ffff88808de91090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000182b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by login/8767: #0: ffff8880a7680090 (&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/8768: #0: ffff88809247e090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000183b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8769: #0: ffff8880a3000090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000185b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8770: #0: ffff8880a4ced090 (&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 3 locks held by syz-executor.3/490: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1092 Comm: khungtaskd Not tainted 5.6.0-rc1-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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.6.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet RIP: 0010:__lock_acquire+0x6/0x1bc0 kernel/locking/lockdep.c:3815 Code: ff ff ff 0f 0b e9 88 fe ff ff e8 e7 a5 a4 ff eb dc e8 e0 a5 a4 ff e9 4b ff ff ff 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 <41> 56 41 55 41 54 53 48 83 e4 f0 48 81 ec 30 01 00 00 45 89 cd 44 RSP: 0018:ffffc90000cdfac0 EFLAGS: 00000006 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff892d98c8 RBP: ffffc90000cdfac8 R08: 0000000000000000 R09: 0000000000000000 R10: fffffbfff12d368d R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000002 R15: ffffffff892d98c8 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fae6e0f3000 CR3: 00000000a35d1000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 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:601 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:754 [inline] batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:821 [inline] batadv_iv_ogm_schedule+0x37a/0xf00 net/batman-adv/bat_iv_ogm.c:865 batadv_iv_send_outstanding_bat_ogm_packet+0x664/0x770 net/batman-adv/bat_iv_ogm.c:1718 process_one_work+0x7f5/0x10f0 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