INFO: task syz-executor.3:10404 blocked for more than 143 seconds. Not tainted 5.5.0-rc5-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D29104 10404 10386 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_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 tty_buffer_lock_exclusive+0x30/0x40 drivers/tty/tty_buffer.c:61 paste_selection+0x11d/0x460 drivers/tty/vt/selection.c:361 tioclinux+0x133/0x480 drivers/tty/vt/vt.c:3044 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45af49 Code: Bad RIP value. RSP: 002b:00007f4e0f9d6c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49 RDX: 0000000020000100 RSI: 000000000000541c RDI: 0000000000000004 RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4e0f9d76d4 R13: 00000000004c64de R14: 00000000004ddb80 R15: 00000000ffffffff Showing all locks held in the system: 2 locks held by kworker/u4:3/104: #0: ffff8880ae937358 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1215 [inline] #0: ffff8880ae937358 (&rq->lock){-.-.}, at: __schedule+0x232/0x1f90 kernel/sched/core.c:4029 #1: ffffffff899a3f00 (rcu_read_lock){....}, at: trace_sched_stat_runtime include/trace/events/sched.h:435 [inline] #1: ffffffff899a3f00 (rcu_read_lock){....}, at: update_curr+0x2ea/0x8d0 kernel/sched/fair.c:859 1 lock held by khungtaskd/1127: #0: ffffffff899a3f00 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 1 lock held by rsyslogd/10211: #0: ffff8880970c5360 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/10333: #0: ffff888092271090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90001ab32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10334: #0: ffff88809f53b090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90001a832e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10335: #0: ffff8880a9b6a090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90001a332e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10336: #0: ffff888094abd090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90001aa32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10337: #0: ffff8880a699b090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90001a932e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10338: #0: ffff8880963db090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90001ac32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/10339: #0: ffff8880a2715090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90001a032e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/9877: 2 locks held by syz-executor.3/10404: #0: ffff888094515090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffff8880a96120a8 (&buf->lock){+.+.}, at: tty_buffer_lock_exclusive+0x30/0x40 drivers/tty/tty_buffer.c:61 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1127 Comm: khungtaskd Not tainted 5.5.0-rc5-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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4300 Comm: udevd Not tainted 5.5.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:match_held_lock+0xe/0x510 kernel/locking/lockdep.c:4013 Code: ff ff 85 c0 78 02 c9 c3 89 c7 89 45 fc e8 8a e6 ff ff 8b 45 fc c9 c3 0f 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 55 48 89 e5 <41> 57 41 56 41 55 41 54 53 48 89 fb 48 83 c7 10 48 89 fa 48 83 ec RSP: 0018:ffffc90001bafa08 EFLAGS: 00000096 RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffc90001bafac0 RDX: 0000000000000001 RSI: ffff8880a3bc3860 RDI: ffff8880a66c6a58 RBP: ffffc90001bafa08 R08: 0000000000000001 R09: ffff8880a66c6a50 R10: fffffbfff14f6980 R11: ffffffff8a7b4c07 R12: ffff8880a66c6a58 R13: ffffffff81d17b9f R14: ffff8880a3bc3860 R15: 0000000000000000 FS: 00007f9b264127a0(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000045af1f CR3: 00000000a6e4e000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: find_held_lock+0x35/0x130 kernel/locking/lockdep.c:4058 __lock_release kernel/locking/lockdep.c:4240 [inline] lock_release+0x254/0x960 kernel/locking/lockdep.c:4503 __mutex_unlock_slowpath+0x86/0x6a0 kernel/locking/mutex.c:1228 mutex_unlock+0xd/0x10 kernel/locking/mutex.c:740 ep_scan_ready_list+0x7bf/0x9e0 fs/eventpoll.c:738 ep_send_events fs/eventpoll.c:1772 [inline] ep_poll+0x1f9/0xe60 fs/eventpoll.c:1909 do_epoll_wait+0x210/0x260 fs/eventpoll.c:2273 __do_sys_epoll_wait fs/eventpoll.c:2283 [inline] __se_sys_epoll_wait fs/eventpoll.c:2280 [inline] __x64_sys_epoll_wait+0x97/0xf0 fs/eventpoll.c:2280 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f9b25b26943 Code: 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 83 3d b5 dc 2a 00 00 75 13 49 89 ca b8 e8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 3b c4 00 00 48 89 04 24 RSP: 002b:00007ffe46a97ca8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8 RAX: ffffffffffffffda RBX: 0000000000000bb8 RCX: 00007f9b25b26943 RDX: 0000000000000008 RSI: 00007ffe46a97da0 RDI: 000000000000000a RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000bb8 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000000000000 R14: 00000000016dd470 R15: 00000000016cf030