loop5: p1 p2 p3 < > p4 < > loop5: p1 p2 p3 < > p4 < > INFO: task syz-executor0:27460 blocked for more than 140 seconds. Not tainted 4.18.0+ #187 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D23672 27460 24568 0x00000004 Call Trace: context_switch kernel/sched/core.c:2823 [inline] __schedule+0x87c/0x1ec0 kernel/sched/core.c:3471 schedule+0xfb/0x450 kernel/sched/core.c:3515 schedule_timeout+0x1cc/0x260 kernel/time/timer.c:1780 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+0x430/0x8d0 kernel/sched/completion.c:136 flush_work+0x531/0x900 kernel/workqueue.c:2918 __cancel_work_timer+0x4bd/0x830 kernel/workqueue.c:2989 cancel_work_sync+0x17/0x20 kernel/workqueue.c:3025 p9_conn_destroy net/9p/trans_fd.c:860 [inline] p9_fd_close+0x36a/0x5b0 net/9p/trans_fd.c:886 p9_client_create+0xa9a/0x1770 net/9p/client.c:1077 v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400 v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135 mount_fs+0xae/0x328 fs/super.c:1277 vfs_kern_mount.part.34+0xdc/0x4e0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2542 [inline] do_mount+0x581/0x30e0 fs/namespace.c:2872 ksys_mount+0x12d/0x140 fs/namespace.c:3088 __do_sys_mount fs/namespace.c:3102 [inline] __se_sys_mount fs/namespace.c:3099 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3099 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457089 Code: 08 e8 3b a9 fb ff 48 8b 44 24 20 48 8b 4c 24 18 48 8b 54 24 38 48 8b 7c 24 48 eb 8d 48 8b 6c 24 50 48 83 c4 58 c3 48 89 04 24 <48> 89 5c 24 08 e8 0d a9 fb ff 48 8b 44 24 40 48 8b 4c 24 48 48 8b RSP: 002b:00007f4218a37c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f4218a386d4 RCX: 0000000000457089 RDX: 0000000020000340 RSI: 0000000020000300 RDI: 0000000000000000 RBP: 0000000000930140 R08: 0000000020000380 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d2310 R14: 00000000004c7a36 R15: 0000000000000001 Showing all locks held in the system: 1 lock held by khungtaskd/770: #0: 000000008950ed40 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4461 1 lock held by rsyslogd/4234: 2 locks held by getty/4324: #0: 000000007aa4361c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000e143a9cc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4325: #0: 00000000de8e4696 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000b1c56681 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4326: #0: 00000000e52aaec0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000b6b14add (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4327: #0: 00000000fef5f8c8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000009f9bf123 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4328: #0: 00000000e02c51ac (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000a9fb0191 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4329: #0: 000000001d18e183 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006b198d5e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4330: #0: 000000005e74caf4 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000001169b1d5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by kworker/0:1/22953: #0: 00000000189f69e9 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000189f69e9 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000189f69e9 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000189f69e9 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 00000000189f69e9 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000189f69e9 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000189f69e9 ((wq_completion)"events"){+.+.}, at: process_one_work+0xb44/0x1ba0 kernel/workqueue.c:2124 #1: 00000000bb6020ef ((work_completion)(&m->wq)){+.+.}, at: process_one_work+0xb9b/0x1ba0 kernel/workqueue.c:2128 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 770 Comm: khungtaskd Not tainted 4.18.0+ #187 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+0x1c9/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline] watchdog+0x9c4/0xf80 kernel/hung_task.c:252 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 2282 Comm: udevd Not tainted 4.18.0+ #187 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:kasan_check_write+0xb/0x20 mm/kasan/kasan.c:277 Code: 89 f6 31 d2 48 89 e5 48 8b 4d 08 e8 3f fe ff ff 5d c3 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 89 f6 ba 01 00 00 00 48 89 e5 <48> 8b 4d 08 e8 1c fe ff ff 5d c3 66 2e 0f 1f 84 00 00 00 00 00 55 RSP: 0018:ffff8801ca4375f8 EFLAGS: 00000086 RAX: 0000000000000000 RBX: ffff8801ca571a40 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff8801ca571a40 RBP: ffff8801ca4375f8 R08: 000000000000267b R09: 0000000000000001 R10: ffff8801ca42cd60 R11: 86bbd860a7e7b6de R12: ffff8801ca571a48 R13: ffff8801ca571a50 R14: ffff8801ca437b28 R15: 0000000000000286 FS: 00007f748a5527a0(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c42ab37000 CR3: 00000001cab17000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: atomic_cmpxchg include/asm-generic/atomic-instrumented.h:57 [inline] queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0xc1/0x200 kernel/locking/spinlock_debug.c:113 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:117 [inline] _raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:152 ep_scan_ready_list+0x3d3/0xf50 fs/eventpoll.c:701 ep_send_events fs/eventpoll.c:1706 [inline] ep_poll+0x3ef/0x1220 fs/eventpoll.c:1832 do_epoll_wait+0x1b0/0x200 fs/eventpoll.c:2190 __do_sys_epoll_wait fs/eventpoll.c:2200 [inline] __se_sys_epoll_wait fs/eventpoll.c:2197 [inline] __x64_sys_epoll_wait+0x97/0xf0 fs/eventpoll.c:2197 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f7489c66943 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:00007ffd7da0dc08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8 RAX: ffffffffffffffda RBX: 0000000000000bb8 RCX: 00007f7489c66943 RDX: 0000000000000008 RSI: 00007ffd7da0dd00 RDI: 000000000000000a RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000bb8 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000000000000 R14: 00000000011273d0 R15: 000000000110e250 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.153 msecs