BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck for 144s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=16/256 in-flight: 7910:rtc_timer_do_work pending: cache_reap, defense_work_handler, defense_work_handler, defense_work_handler, defense_work_handler, rht_deferred_worker, destroy_super_work, nfc_urelease_event_work, kernfs_notify_workfn, nfc_urelease_event_work, nfc_urelease_event_work, nfc_urelease_event_work, destroy_super_work, xfrm_state_gc_task, nfc_urelease_event_work ====================================================== WARNING: possible circular locking dependency detected 4.19.36 #4 Not tainted ------------------------------------------------------ swapper/0/0 is trying to acquire lock: 0000000087c7c7d5 (console_owner){-.-.}, at: log_next kernel/printk/printk.c:497 [inline] 0000000087c7c7d5 (console_owner){-.-.}, at: console_unlock+0x41f/0x10c0 kernel/printk/printk.c:2397 but task is already holding lock: 000000008356a144 (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold+0x879/0x11dc kernel/workqueue.c:4557 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&(&pool->lock)->rlock){-.-.}: __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/0x10e0 kernel/workqueue.c:1417 queue_work_on+0x192/0x200 kernel/workqueue.c:1486 queue_work include/linux/workqueue.h:512 [inline] schedule_work include/linux/workqueue.h:570 [inline] put_pwq kernel/workqueue.c:1090 [inline] put_pwq+0x178/0x1d0 kernel/workqueue.c:1075 put_pwq_unlocked.part.0+0x34/0x70 kernel/workqueue.c:1107 put_pwq_unlocked kernel/workqueue.c:1101 [inline] destroy_workqueue+0x617/0x6f0 kernel/workqueue.c:4217 do_floppy_init drivers/block/floppy.c:4704 [inline] floppy_async_init+0x202c/0x216b drivers/block/floppy.c:4721 async_run_entry_fn+0x126/0x570 kernel/async.c:127 process_one_work+0x98e/0x1760 kernel/workqueue.c:2153 worker_thread+0x98/0xe40 kernel/workqueue.c:2296 kthread+0x357/0x430 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 -> #3 (&pool->lock/1){..-.}: __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/0x10e0 kernel/workqueue.c:1417 queue_work_on+0x192/0x200 kernel/workqueue.c:1486 queue_work include/linux/workqueue.h:512 [inline] tty_schedule_flip drivers/tty/tty_buffer.c:408 [inline] tty_flip_buffer_push+0xc5/0x100 drivers/tty/tty_buffer.c:551 pty_write+0x1a6/0x200 drivers/tty/pty.c:124 n_tty_write+0xb06/0x1100 drivers/tty/n_tty.c:2354 do_tty_write drivers/tty/tty_io.c:960 [inline] tty_write+0x45b/0x7a0 drivers/tty/tty_io.c:1044 __vfs_write+0x116/0x820 fs/read_write.c:485 vfs_write+0x20c/0x560 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){-.-.}: __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:288 tty_port_default_wakeup+0x16/0x40 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x5d/0x70 drivers/tty/tty_port.c:390 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+0x1e2/0x270 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+0x102/0x1e0 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:791 generic_handle_irq_desc include/linux/irqdesc.h:155 [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 arch_local_irq_restore arch/x86/include/asm/paravirt.h:788 [inline] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irqrestore+0x95/0xe0 kernel/locking/spinlock.c:184 spin_unlock_irqrestore include/linux/spinlock.h:384 [inline] uart_write+0x3a9/0x6f0 drivers/tty/serial/serial_core.c:615 process_output_block drivers/tty/n_tty.c:593 [inline] n_tty_write+0x3ff/0x1100 drivers/tty/n_tty.c:2331 do_tty_write drivers/tty/tty_io.c:960 [inline] tty_write+0x45b/0x7a0 drivers/tty/tty_io.c:1044 redirected_tty_write+0xb2/0xc0 drivers/tty/tty_io.c:1065 __vfs_write+0x116/0x820 fs/read_write.c:485 vfs_write+0x20c/0x560 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 -> #1 (&port_lock_key){-.-.}: __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+0x7ed/0xa10 drivers/tty/serial/8250/8250_port.c:3247 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:590 call_console_drivers kernel/printk/printk.c:1729 [inline] console_unlock+0xbe4/0x10c0 kernel/printk/printk.c:2410 vprintk_emit+0x238/0x690 kernel/printk/printk.c:1927 vprintk_default+0x28/0x30 kernel/printk/printk.c:1968 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2001 register_console+0x787/0xb90 kernel/printk/printk.c:2725 univ8250_console_init+0x3e/0x4b drivers/tty/serial/8250/8250_core.c:685 console_init+0x4f7/0x761 kernel/printk/printk.c:2811 start_kernel+0x59f/0x8c8 init/main.c:661 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){-.-.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3903 console_lock_spinning_enable kernel/printk/printk.c:1592 [inline] console_unlock+0x489/0x10c0 kernel/printk/printk.c:2407 vprintk_emit+0x238/0x690 kernel/printk/printk.c:1927 vprintk_default+0x28/0x30 kernel/printk/printk.c:1968 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2001 show_pwq kernel/workqueue.c:4464 [inline] show_workqueue_state.cold+0x9e4/0x11dc kernel/workqueue.c:4559 wq_watchdog_timer_fn+0x516/0x5a0 kernel/workqueue.c:5571 call_timer_fn+0x190/0x720 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers kernel/time/timer.c:1682 [inline] __run_timers kernel/time/timer.c:1650 [inline] run_timer_softirq+0xd03/0x1700 kernel/time/timer.c:1697 __do_softirq+0x266/0x92f kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x180/0x1d0 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x14a/0x570 arch/x86/kernel/apic/apic.c:1056 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:867 native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:57 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:552 default_idle_call+0x36/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x377/0x560 kernel/sched/idle.c:262 cpu_startup_entry+0xc8/0xe0 kernel/sched/idle.c:368 rest_init+0xf1/0xf6 init/main.c:442 start_kernel+0x88f/0x8c8 init/main.c:738 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: 00000000a03b3148 ((&wq_watchdog_timer)){+.-.}, at: lockdep_copy_map include/linux/lockdep.h:168 [inline] #0: 00000000a03b3148 ((&wq_watchdog_timer)){+.-.}, at: call_timer_fn+0xda/0x720 kernel/time/timer.c:1316 #1: 0000000082662955 (rcu_read_lock_sched){....}, at: show_workqueue_state+0x0/0x120 kernel/workqueue.c:4429 #2: 000000008356a144 (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold+0x879/0x11dc kernel/workqueue.c:4557 #3: 00000000bec2410a (console_lock){+.+.}, at: console_trylock_spinning kernel/printk/printk.c:1654 [inline] #3: 00000000bec2410a (console_lock){+.+.}, at: vprintk_emit+0x21d/0x690 kernel/printk/printk.c:1926 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.36 #4 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:1221 check_prev_add kernel/locking/lockdep.c:1861 [inline] check_prevs_add kernel/locking/lockdep.c:1974 [inline] validate_chain kernel/locking/lockdep.c:2415 [inline] __lock_acquire+0x2e6d/0x48f0 kernel/locking/lockdep.c:3411 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3903 console_lock_spinning_enable kernel/printk/printk.c:1592 [inline] console_unlock+0x489/0x10c0 kernel/printk/printk.c:2407 vprintk_emit+0x238/0x690 kernel/printk/printk.c:1927 vprintk_default+0x28/0x30 kernel/printk/printk.c:1968 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 printk+0xba/0xed kernel/printk/printk.c:2001 show_pwq kernel/workqueue.c:4464 [inline] show_workqueue_state.cold+0x9e4/0x11dc kernel/workqueue.c:4559 wq_watchdog_timer_fn+0x516/0x5a0 kernel/workqueue.c:5571 call_timer_fn+0x190/0x720 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers kernel/time/timer.c:1682 [inline] __run_timers kernel/time/timer.c:1650 [inline] run_timer_softirq+0xd03/0x1700 kernel/time/timer.c:1697 __do_softirq+0x266/0x92f kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x180/0x1d0 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x14a/0x570 arch/x86/kernel/apic/apic.c:1056 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:867 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 89 f3 b2 fa 48 8b 45 d8 e9 ce fe ff ff 48 89 df e8 78 f3 b2 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:ffffffff88607ca8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff10e4664 RBX: ffffffff88679e80 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffffffff8867a6fc RBP: ffffffff88607cd8 R08: ffffffff88679e80 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff88723310 R14: 0000000000000000 R15: 0000000000000000 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:552 default_idle_call+0x36/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x377/0x560 kernel/sched/idle.c:262 cpu_startup_entry+0xc8/0xe0 kernel/sched/idle.c:368 rest_init+0xf1/0xf6 init/main.c:442 start_kernel+0x88f/0x8c8 init/main.c:738 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=2/256 pending: 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: 12012:fsnotify_mark_destroy_workfn fsnotify_mark_destroy_workfn, 2752:fsnotify_connector_destroy_workfn fsnotify_connector_destroy_workfn workqueue events_power_efficient: flags=0x80 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=2/256 pending: check_lifetime, do_cache_clean workqueue rcu_gp: flags=0x8 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=3/256 pending: srcu_invoke_callbacks, process_srcu, wait_rcu_exp_gp 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 workqueue bat_events: flags=0xe000a pwq 4: cpus=0-1 flags=0x4 nice=0 active=1/1 pending: batadv_dat_purge delayed: batadv_bla_periodic_work, batadv_purge_orig, batadv_purge_orig, batadv_nc_worker, batadv_nc_worker, batadv_nc_worker, batadv_nc_worker, batadv_nc_worker pool 2: cpus=1 node=0 flags=0x0 nice=0 hung=145s workers=5 idle: 9823 19 25349 10456 pool 4: cpus=0-1 flags=0x4 nice=0 hung=1s workers=9 idle: 26 6988 9545 2299 18941 8052 6991