BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck for 158s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=18/256 in-flight: 3480:rtc_timer_do_work pending: kernfs_notify_workfn, vmpressure_work_fn, cache_reap, proc_cleanup_work, proc_cleanup_work, defense_work_handler, defense_work_handler, defense_work_handler, defense_work_handler, defense_work_handler, free_obj_work, switchdev_deferred_process_work, rht_deferred_worker, rht_deferred_worker, binder_deferred_func, psi_update_work, psi_update_work ====================================================== WARNING: possible circular locking dependency detected 5.0.0-rc8-next-20190304 #2 Not tainted ------------------------------------------------------ swapper/0/0 is trying to acquire lock: 0000000039b4979d (console_owner){-.-.}, at: log_next kernel/printk/printk.c:500 [inline] 0000000039b4979d (console_owner){-.-.}, at: console_unlock+0x3fc/0xeb0 kernel/printk/printk.c:2443 but task is already holding lock: 000000008eb0487d (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold+0x879/0x11dc kernel/workqueue.c:4718 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&(&pool->lock)->rlock){-.-.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __queue_work+0x23d/0x1180 kernel/workqueue.c:1449 queue_work_on+0x192/0x200 kernel/workqueue.c:1518 queue_work include/linux/workqueue.h:494 [inline] schedule_work include/linux/workqueue.h:552 [inline] put_pwq kernel/workqueue.c:1122 [inline] put_pwq+0x178/0x1d0 kernel/workqueue.c:1107 put_pwq_unlocked.part.0+0x34/0x70 kernel/workqueue.c:1139 put_pwq_unlocked kernel/workqueue.c:1133 [inline] destroy_workqueue+0x623/0x700 kernel/workqueue.c:4378 do_floppy_init drivers/block/floppy.c:4699 [inline] floppy_async_init+0x2031/0x2183 drivers/block/floppy.c:4717 async_run_entry_fn+0x126/0x570 kernel/async.c:127 process_one_work+0x98e/0x1790 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x357/0x430 kernel/kthread.c:253 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 -> #3 (&pool->lock/1){..-.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __queue_work+0x23d/0x1180 kernel/workqueue.c:1449 queue_work_on+0x192/0x200 kernel/workqueue.c:1518 queue_work include/linux/workqueue.h:494 [inline] tty_schedule_flip drivers/tty/tty_buffer.c:413 [inline] tty_flip_buffer_push+0xc5/0x100 drivers/tty/tty_buffer.c:556 pty_write+0x1a6/0x200 drivers/tty/pty.c:125 n_tty_write+0xb06/0x1150 drivers/tty/n_tty.c:2356 do_tty_write drivers/tty/tty_io.c:961 [inline] tty_write+0x45b/0x7a0 drivers/tty/tty_io.c:1045 __vfs_write+0x8d/0x110 fs/read_write.c:485 vfs_write+0x20c/0x580 fs/read_write.c:549 ksys_write+0xea/0x1f0 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&(&port->lock)->rlock){-.-.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 tty_port_tty_get+0x22/0x80 drivers/tty/tty_port.c:287 tty_port_default_wakeup+0x16/0x40 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x5d/0x70 drivers/tty/tty_port.c:387 uart_write_wakeup+0x46/0x70 drivers/tty/serial/serial_core.c:103 serial8250_tx_chars+0x4a4/0xb20 drivers/tty/serial/8250/8250_port.c:1806 serial8250_handle_irq.part.0+0x1be/0x2e0 drivers/tty/serial/8250/8250_port.c:1879 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1865 [inline] serial8250_default_handle_irq+0xc5/0x150 drivers/tty/serial/8250/8250_port.c:1895 serial8250_interrupt+0xfb/0x1a0 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x146/0x900 kernel/irq/handle.c:149 handle_irq_event_percpu+0x74/0x160 kernel/irq/handle.c:189 handle_irq_event+0xa7/0x134 kernel/irq/handle.c:206 handle_edge_irq+0x264/0x8e0 kernel/irq/chip.c:822 generic_handle_irq_desc include/linux/irqdesc.h:156 [inline] handle_irq+0x252/0x3d8 arch/x86/kernel/irq_64.c:78 do_IRQ+0x99/0x1d0 arch/x86/kernel/irq.c:246 ret_from_intr+0x0/0x1e native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:57 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:567 default_idle_call+0x36/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x386/0x570 kernel/sched/idle.c:262 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:353 start_secondary+0x360/0x4d0 arch/x86/kernel/smpboot.c:267 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&port_lock_key){-.-.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 serial8250_console_write+0x253/0x9c0 drivers/tty/serial/8250/8250_port.c:3245 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:586 call_console_drivers kernel/printk/printk.c:1775 [inline] console_unlock+0xb1e/0xeb0 kernel/printk/printk.c:2456 vprintk_emit+0x280/0x6d0 kernel/printk/printk.c:1979 vprintk_default+0x28/0x30 kernel/printk/printk.c:2006 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2039 register_console+0x74d/0xb50 kernel/printk/printk.c:2771 univ8250_console_init+0x3e/0x4b drivers/tty/serial/8250/8250_core.c:681 console_init+0x4f7/0x761 kernel/printk/printk.c:2857 start_kernel+0x574/0x84f init/main.c:675 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #0 (console_owner){-.-.}: check_prevs_add kernel/locking/lockdep.c:2324 [inline] validate_chain kernel/locking/lockdep.c:2705 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3692 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 console_lock_spinning_enable kernel/printk/printk.c:1638 [inline] console_unlock+0x466/0xeb0 kernel/printk/printk.c:2453 vprintk_emit+0x280/0x6d0 kernel/printk/printk.c:1979 vprintk_default+0x28/0x30 kernel/printk/printk.c:2006 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2039 show_pwq kernel/workqueue.c:4625 [inline] show_workqueue_state.cold+0x9e4/0x11dc kernel/workqueue.c:4720 wq_watchdog_timer_fn+0x516/0x5a0 kernel/workqueue.c:5732 call_timer_fn+0x190/0x720 kernel/time/timer.c:1325 expire_timers kernel/time/timer.c:1362 [inline] __run_timers kernel/time/timer.c:1681 [inline] __run_timers kernel/time/timer.c:1649 [inline] run_timer_softirq+0xd03/0x1700 kernel/time/timer.c:1696 __do_softirq+0x266/0x95a kernel/softirq.c:293 invoke_softirq kernel/softirq.c:374 [inline] irq_exit+0x180/0x1d0 kernel/softirq.c:414 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x14a/0x570 arch/x86/kernel/apic/apic.c:1062 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807 native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:57 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:567 default_idle_call+0x36/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x386/0x570 kernel/sched/idle.c:262 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:353 rest_init+0x245/0x37b init/main.c:450 arch_call_rest_init+0xe/0x1b start_kernel+0x816/0x84f init/main.c:747 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 other info that might help us debug this: Chain exists of: console_owner --> &pool->lock/1 --> &(&pool->lock)->rlock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&pool->lock)->rlock); lock(&pool->lock/1); lock(&(&pool->lock)->rlock); lock(console_owner); *** DEADLOCK *** 4 locks held by swapper/0/0: #0: 000000006b49d98e ((&wq_watchdog_timer)){+.-.}, at: lockdep_copy_map include/linux/lockdep.h:170 [inline] #0: 000000006b49d98e ((&wq_watchdog_timer)){+.-.}, at: call_timer_fn+0xda/0x720 kernel/time/timer.c:1315 #1: 000000002c7e289b (rcu_read_lock_sched){....}, at: show_workqueue_state+0x0/0x120 kernel/workqueue.c:4590 #2: 000000008eb0487d (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold+0x879/0x11dc kernel/workqueue.c:4718 #3: 000000000dce2df0 (console_lock){+.+.}, at: console_trylock_spinning kernel/printk/printk.c:1700 [inline] #3: 000000000dce2df0 (console_lock){+.+.}, at: vprintk_emit+0x267/0x6d0 kernel/printk/printk.c:1978 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.0.0-rc8-next-20190304 #2 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+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1562 check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2211 check_prevs_add kernel/locking/lockdep.c:2324 [inline] validate_chain kernel/locking/lockdep.c:2705 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3692 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 console_lock_spinning_enable kernel/printk/printk.c:1638 [inline] console_unlock+0x466/0xeb0 kernel/printk/printk.c:2453 vprintk_emit+0x280/0x6d0 kernel/printk/printk.c:1979 vprintk_default+0x28/0x30 kernel/printk/printk.c:2006 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2039 show_pwq kernel/workqueue.c:4625 [inline] show_workqueue_state.cold+0x9e4/0x11dc kernel/workqueue.c:4720 wq_watchdog_timer_fn+0x516/0x5a0 kernel/workqueue.c:5732 call_timer_fn+0x190/0x720 kernel/time/timer.c:1325 expire_timers kernel/time/timer.c:1362 [inline] __run_timers kernel/time/timer.c:1681 [inline] __run_timers kernel/time/timer.c:1649 [inline] run_timer_softirq+0xd03/0x1700 kernel/time/timer.c:1696 __do_softirq+0x266/0x95a kernel/softirq.c:293 invoke_softirq kernel/softirq.c:374 [inline] irq_exit+0x180/0x1d0 kernel/softirq.c:414 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x14a/0x570 arch/x86/kernel/apic/apic.c:1062 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807 RIP: 0010:native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:58 Code: ff ff ff 48 89 c7 48 89 45 d8 e8 39 4a 99 fa 48 8b 45 d8 e9 ce fe ff ff 48 89 df e8 28 4a 99 fa eb 82 90 90 90 90 90 90 fb f4 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 f4 c3 90 90 90 90 90 90 RSP: 0018:ffffffff88807d08 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff11252b9 RBX: ffffffff8887e080 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff8887e8fc RBP: ffffffff88807d38 R08: ffffffff8887e080 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff889295b8 R14: 0000000000000000 R15: 0000000000000000 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:567 default_idle_call+0x36/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x386/0x570 kernel/sched/idle.c:262 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:353 rest_init+0x245/0x37b init/main.c:450 arch_call_rest_init+0xe/0x1b start_kernel+0x816/0x84f init/main.c:747 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 workqueue events_long: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=3/256 pending: br_fdb_cleanup, br_fdb_cleanup, br_fdb_cleanup workqueue events_unbound: flags=0x2 pwq 4: cpus=0-1 flags=0x4 nice=0 active=4/512 in-flight: 2531:fsnotify_connector_destroy_workfn fsnotify_connector_destroy_workfn, 45:fsnotify_mark_destroy_workfn fsnotify_mark_destroy_workfn BAR(14181) workqueue events_power_efficient: flags=0x80 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=2/256 pending: gc_worker, neigh_periodic_work workqueue rcu_gp: flags=0x8 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=4/256 pending: srcu_invoke_callbacks, process_srcu, process_srcu, process_srcu workqueue mm_percpu_wq: flags=0x8 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/256 pending: vmstat_update workqueue ipv6_addrconf: flags=0x40008 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/1 pending: addrconf_verify_work workqueue krxrpcd: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/1 pending: rxrpc_peer_keepalive_worker delayed: rxrpc_peer_keepalive_worker, rxrpc_peer_keepalive_worker, rxrpc_peer_keepalive_worker, rxrpc_peer_keepalive_worker workqueue bat_events: flags=0xe000a pwq 4: cpus=0-1 flags=0x4 nice=0 active=1/1 pending: batadv_bla_periodic_work delayed: batadv_dat_purge, batadv_bla_periodic_work, batadv_dat_purge, batadv_purge_orig, batadv_nc_worker pool 2: cpus=1 node=0 flags=0x0 nice=0 hung=159s workers=4 idle: 17 22 7772 pool 4: cpus=0-1 flags=0x4 nice=0 hung=1s workers=7 idle: 77 11244 21 7 8272