BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck for 193s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=29/256 in-flight: 28916:rtc_timer_do_work pending: kernfs_notify_workfn, vmpressure_work_fn, psi_update_work, psi_update_work, defense_work_handler, defense_work_handler, defense_work_handler, defense_work_handler, defense_work_handler, defense_work_handler, psi_update_work, psi_update_work, cache_reap, psi_update_work, psi_update_work, psi_update_work, proc_cleanup_work, proc_cleanup_work, proc_cleanup_work, rfkill_global_led_trigger_worker, pwq_unbound_release_workfn, pwq_unbound_release_workfn, release_one_tty, release_one_tty, proc_cleanup_work, free_obj_work, proc_cleanup_work, proc_cleanup_work ====================================================== WARNING: possible circular locking dependency detected 4.20.0-rc5+ #144 Not tainted ------------------------------------------------------ syz-fuzzer/6041 is trying to acquire lock: 00000000ca7f8cdf (console_owner){-.-.}, at: log_next kernel/printk/printk.c:491 [inline] 00000000ca7f8cdf (console_owner){-.-.}, at: console_unlock+0x570/0x1190 kernel/printk/printk.c:2401 but task is already holding lock: 00000000d972ad71 (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold.49+0xad0/0x159a 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+0x2d/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __queue_work+0x2ff/0x1440 kernel/workqueue.c:1417 queue_work_on+0x19a/0x1e0 kernel/workqueue.c:1486 queue_work include/linux/workqueue.h:512 [inline] schedule_work include/linux/workqueue.h:570 [inline] put_pwq+0x175/0x1c0 kernel/workqueue.c:1090 put_pwq_unlocked.part.27+0x34/0x70 kernel/workqueue.c:1107 put_pwq_unlocked kernel/workqueue.c:1101 [inline] destroy_workqueue+0x868/0x9c0 kernel/workqueue.c:4217 do_floppy_init drivers/block/floppy.c:4708 [inline] floppy_async_init+0x1fed/0x2144 drivers/block/floppy.c:4726 async_run_entry_fn+0x1c4/0x7f0 kernel/async.c:127 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296 kthread+0x35a/0x440 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 -> #3 (&pool->lock/1){..-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __queue_work+0x2ff/0x1440 kernel/workqueue.c:1417 queue_work_on+0x19a/0x1e0 kernel/workqueue.c:1486 queue_work include/linux/workqueue.h:512 [inline] tty_schedule_flip+0x14c/0x1d0 drivers/tty/tty_buffer.c:413 tty_flip_buffer_push+0x15/0x20 drivers/tty/tty_buffer.c:556 pty_write+0x19d/0x1f0 drivers/tty/pty.c:125 n_tty_write+0xc5b/0x11a0 drivers/tty/n_tty.c:2354 do_tty_write drivers/tty/tty_io.c:959 [inline] tty_write+0x3f1/0x880 drivers/tty/tty_io.c:1043 __vfs_write+0x119/0x9f0 fs/read_write.c:485 vfs_write+0x1fc/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 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+0x1b9/0x820 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+0x99/0xd0 kernel/locking/spinlock.c:152 tty_port_tty_get+0x20/0x80 drivers/tty/tty_port.c:287 tty_port_default_wakeup+0x15/0x40 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x5d/0x70 drivers/tty/tty_port.c:387 uart_write_wakeup+0x44/0x60 drivers/tty/serial/serial_core.c:103 serial8250_tx_chars+0x4be/0xb60 drivers/tty/serial/8250/8250_port.c:1825 serial8250_handle_irq.part.23+0x1ee/0x280 drivers/tty/serial/8250/8250_port.c:1898 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1884 [inline] serial8250_default_handle_irq+0xc8/0x150 drivers/tty/serial/8250/8250_port.c:1914 serial8250_interrupt+0xef/0x190 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x195/0xb30 kernel/irq/handle.c:149 handle_irq_event_percpu+0xa0/0x1d0 kernel/irq/handle.c:189 handle_irq_event+0xa7/0x135 kernel/irq/handle.c:206 handle_edge_irq+0x227/0x880 kernel/irq/chip.c:791 generic_handle_irq_desc include/linux/irqdesc.h:154 [inline] handle_irq+0x252/0x3d8 arch/x86/kernel/irq_64.c:78 do_IRQ+0x98/0x1c0 arch/x86/kernel/irq.c:246 ret_from_intr+0x0/0x1e native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57 arch_safe_halt arch/x86/include/asm/paravirt.h:151 [inline] default_idle+0xbf/0x490 arch/x86/kernel/process.c:561 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:552 default_idle_call+0x6d/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x49b/0x5c0 kernel/sched/idle.c:262 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:353 rest_init+0x243/0x372 init/main.c:443 arch_call_rest_init+0xe/0x1b start_kernel+0x9f5/0xa30 init/main.c:745 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&port_lock_key){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152 serial8250_console_write+0x8e8/0xb10 drivers/tty/serial/8250/8250_port.c:3266 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:586 call_console_drivers kernel/printk/printk.c:1728 [inline] console_unlock+0xb1f/0x1190 kernel/printk/printk.c:2414 vprintk_emit+0x391/0x990 kernel/printk/printk.c:1922 vprintk_default+0x28/0x30 kernel/printk/printk.c:1964 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1997 register_console+0x8df/0xcf0 kernel/printk/printk.c:2729 univ8250_console_init+0x3f/0x4b drivers/tty/serial/8250/8250_core.c:681 console_init+0x6b4/0x9e7 kernel/printk/printk.c:2815 start_kernel+0x70e/0xa30 init/main.c:667 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #0 (console_owner){-.-.}: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 console_lock_spinning_enable kernel/printk/printk.c:1591 [inline] console_unlock+0x5dd/0x1190 kernel/printk/printk.c:2411 vprintk_emit+0x391/0x990 kernel/printk/printk.c:1922 vprintk_default+0x28/0x30 kernel/printk/printk.c:1964 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1997 show_pwq kernel/workqueue.c:4464 [inline] show_workqueue_state.cold.49+0xc6c/0x159a kernel/workqueue.c:4559 wq_watchdog_timer_fn+0x6ea/0x810 kernel/workqueue.c:5571 call_timer_fn+0x272/0x920 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers+0x7e5/0xc70 kernel/time/timer.c:1682 run_timer_softirq+0x88/0xb0 kernel/time/timer.c:1697 __do_softirq+0x308/0xb7e kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x17f/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:804 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 syz-fuzzer/6041: #0: 00000000092f7aa3 ((&wq_watchdog_timer)){+.-.}, at: lockdep_copy_map include/linux/lockdep.h:173 [inline] #0: 00000000092f7aa3 ((&wq_watchdog_timer)){+.-.}, at: call_timer_fn+0x1db/0x920 kernel/time/timer.c:1316 #1: 0000000081ad29a4 (rcu_read_lock_sched){....}, at: show_workqueue_state+0x0/0x1d0 kernel/workqueue.c:4423 #2: 00000000d972ad71 (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold.49+0xad0/0x159a kernel/workqueue.c:4557 #3: 00000000f25a2fdd (console_lock){+.+.}, at: console_trylock_spinning kernel/printk/printk.c:1653 [inline] #3: 00000000f25a2fdd (console_lock){+.+.}, at: vprintk_emit+0x372/0x990 kernel/printk/printk.c:1921 stack backtrace: CPU: 0 PID: 6041 Comm: syz-fuzzer Not tainted 4.20.0-rc5+ #144 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+0x244/0x39d lib/dump_stack.c:113 print_circular_bug.isra.35.cold.54+0x1bd/0x27d kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1863 [inline] check_prevs_add kernel/locking/lockdep.c:1976 [inline] validate_chain kernel/locking/lockdep.c:2347 [inline] __lock_acquire+0x3399/0x4c20 kernel/locking/lockdep.c:3341 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 console_lock_spinning_enable kernel/printk/printk.c:1591 [inline] console_unlock+0x5dd/0x1190 kernel/printk/printk.c:2411 vprintk_emit+0x391/0x990 kernel/printk/printk.c:1922 vprintk_default+0x28/0x30 kernel/printk/printk.c:1964 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1997 show_pwq kernel/workqueue.c:4464 [inline] show_workqueue_state.cold.49+0xc6c/0x159a kernel/workqueue.c:4559 wq_watchdog_timer_fn+0x6ea/0x810 kernel/workqueue.c:5571 call_timer_fn+0x272/0x920 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers+0x7e5/0xc70 kernel/time/timer.c:1682 ? __sa Lost 43 message(s)! workqueue events_long: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/256 pending: br_fdb_cleanup workqueue events_unbound: flags=0x2 pwq 4: cpus=0-1 flags=0x4 nice=0 active=4/512 in-flight: 10057:fsnotify_mark_destroy_workfn fsnotify_mark_destroy_workfn BAR(17507), 183: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=6/256 pending: gc_worker, neigh_periodic_work, check_lifetime, neigh_periodic_work, do_cache_clean, device_uncache_fw_images_work 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 memcg_kmem_cache: flags=0x0 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/1 pending: memcg_kmem_cache_create_func delayed: memcg_kmem_cache_create_func, memcg_kmem_cache_create_func, memcg_kmem_cache_create_func workqueue ipv6_addrconf: flags=0x40008 pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/1 pending: addrconf_verify_work pool 2: cpus=1 node=0 flags=0x0 nice=0 hung=194s workers=3 idle: 4080 6212 pool 4: cpus=0-1 flags=0x4 nice=0 hung=98s workers=6 idle: 21 245 7 967