INFO: task login:10473 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. login D23272 10473 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 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_work+0x4fe/0xa50 kernel/workqueue.c:3041 flush_work+0x18/0x20 kernel/workqueue.c:3062 tty_buffer_flush_work+0x16/0x20 drivers/tty/tty_buffer.c:618 n_tty_read+0xaea/0x1bf0 drivers/tty/n_tty.c:2199 tty_read+0x1a0/0x2a0 drivers/tty/tty_io.c:869 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 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+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f61e2cf2310 Code: Bad RIP value. RSP: 002b:00007ffc3e1a3e48 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f61e2cf2310 RDX: 00000000000001ff RSI: 00007ffc3e1a40b0 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007f61e35d5700 R09: 0000000000000000 R10: 00007ffc3e1a3e00 R11: 0000000000000246 R12: 00007ffc3e1a40b0 R13: 0000000000000000 R14: 0000000000000001 R15: 000000000060b798 INFO: task kworker/u4:6:13932 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. kworker/u4:6 D24392 13932 2 0x80004000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118 flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:505 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264 process_scheduled_works kernel/workqueue.c:2326 [inline] worker_thread+0x750/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Showing all locks held in the system: 1 lock held by khungtaskd/1128: #0: ffffffff899a3f00 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 1 lock held by rsyslogd/10352: #0: ffff88809277e120 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by login/10473: #0: ffff888093461090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017a32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10474: #0: ffff8880a9a7a090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017f32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10475: #0: ffff8880a9a77090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018032e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10476: #0: ffff8880a9a80090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018132e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10477: #0: ffff88809335b090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000177b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10478: #0: ffff8880920c8090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018232e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10479: #0: ffff8880920ec090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000175b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 3 locks held by kworker/u4:6/13932: #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2235 #1: ffffc90004b77dc0 ((work_completion)(&buf->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2239 #2: ffff8880aa5bd0a8 (&buf->lock){+.+.}, at: flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:505 4 locks held by syz-executor.0/7114: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1128 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+0x197/0x210 lib/dump_stack.c:118 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+0xb11/0x10c0 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 343 Comm: kworker/u4:5 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:trace_lock_release include/trace/events/lock.h:58 [inline] RIP: 0010:lock_release+0x1a9/0x960 kernel/locking/lockdep.c:4502 Code: 0f 87 b3 04 00 00 45 89 ff be 08 00 00 00 4c 89 f8 48 c1 f8 06 48 8d 3c c5 c0 4c 7b 8a e8 2f b8 57 00 4c 0f a3 3d a7 7c 20 09 <0f> 82 48 04 00 00 48 c7 c0 b4 7e 7b 8a 41 c7 46 b0 01 00 00 00 48 RSP: 0018:ffffc900020b7c00 EFLAGS: 00000047 RAX: 0000000000000001 RBX: 1ffff92000416f85 RCX: ffffffff815ad011 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8a7b4cc0 RBP: ffffc900020b7cd0 R08: 1ffffffff14f6998 R09: fffffbfff14f6999 R10: fffffbfff14f6998 R11: ffffffff8a7b4cc7 R12: ffffffff899a3f00 R13: ffffffff87b61caa R14: ffffc900020b7ca8 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 000000005426c000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_lock_release include/linux/rcupdate.h:213 [inline] rcu_read_unlock include/linux/rcupdate.h:671 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:411 [inline] batadv_nc_worker+0x220/0x760 net/batman-adv/network-coding.c:718 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264 worker_thread+0x98/0xe40 kernel/workqueue.c:2410 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352