audit: type=1326 audit(1539630137.492:151): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=24059 comm="syz-executor4" exe="/root/syz-executor4" sig=9 arch=c000003e syscall=228 compat=0 ip=0x45a3ca code=0x0 BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 191s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=8/256 pending: vmstat_shepherd, cache_reap, defense_work_handler, defense_work_handler, defense_work_handler, defense_work_handler, defense_work_handler, check_corruption ====================================================== WARNING: possible circular locking dependency detected 4.19.0-rc8+ #64 Not tainted ------------------------------------------------------ syz-executor0/24016 is trying to acquire lock: 0000000065519c27 (console_owner){-.-.}, at: log_next kernel/printk/printk.c:497 [inline] 0000000065519c27 (console_owner){-.-.}, at: console_unlock+0x560/0x1160 kernel/printk/printk.c:2392 but task is already holding lock: 000000004488cd6c (&(&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+0x34c/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.28+0x34/0x70 kernel/workqueue.c:1107 put_pwq_unlocked kernel/workqueue.c:1101 [inline] destroy_workqueue+0x868/0x9c0 kernel/workqueue.c:4217 tipc_topsrv_work_stop net/tipc/topsrv.c:641 [inline] tipc_topsrv_stop+0x4ad/0x6ca net/tipc/topsrv.c:700 tipc_exit_net+0x15/0x40 net/tipc/core.c:100 ops_exit_list.isra.7+0xb0/0x160 net/core/net_namespace.c:153 cleanup_net+0x555/0xb10 net/core/net_namespace.c:551 process_one_work+0xc90/0x1b90 kernel/workqueue.c:2153 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296 kthread+0x35a/0x420 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+0x2d/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __queue_work+0x34c/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:408 tty_flip_buffer_push+0x15/0x20 drivers/tty/tty_buffer.c:547 pty_write+0x19d/0x1f0 drivers/tty/pty.c:124 n_tty_write+0xc5b/0x11a0 drivers/tty/n_tty.c:2340 do_tty_write drivers/tty/tty_io.c:958 [inline] tty_write+0x3f1/0x880 drivers/tty/tty_io.c:1042 __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:288 tty_port_default_wakeup+0x15/0x40 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x5d/0x70 drivers/tty/tty_port.c:390 uart_write_wakeup+0x44/0x60 drivers/tty/serial/serial_core.c:103 serial8250_tx_chars+0x4be/0xb60 drivers/tty/serial/8250/8250_port.c:1806 serial8250_handle_irq.part.23+0x1ee/0x280 drivers/tty/serial/8250/8250_port.c:1879 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1865 [inline] serial8250_default_handle_irq+0xc8/0x150 drivers/tty/serial/8250/8250_port.c:1895 serial8250_interrupt+0xfa/0x1d0 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x1e6/0xb00 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 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+0xaf/0xd0 kernel/locking/spinlock.c:184 spin_unlock_irqrestore include/linux/spinlock.h:384 [inline] uart_write+0x4b2/0x740 drivers/tty/serial/serial_core.c:598 process_output_block drivers/tty/n_tty.c:580 [inline] n_tty_write+0x6c1/0x11a0 drivers/tty/n_tty.c:2317 do_tty_write drivers/tty/tty_io.c:958 [inline] tty_write+0x3f1/0x880 drivers/tty/tty_io.c:1042 redirected_tty_write+0xaf/0xc0 drivers/tty/tty_io.c:1063 __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 -> #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+0x8dd/0xb10 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:1724 [inline] console_unlock+0xcd7/0x1160 kernel/printk/printk.c:2405 vprintk_emit+0x33d/0x930 kernel/printk/printk.c:1922 vprintk_default+0x28/0x30 kernel/printk/printk.c:1963 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1996 register_console+0x7e6/0xc00 kernel/printk/printk.c:2720 univ8250_console_init+0x3f/0x4b drivers/tty/serial/8250/8250_core.c:685 console_init+0x6ac/0x9dc kernel/printk/printk.c:2806 start_kernel+0x613/0x92f init/main.c:661 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:3900 console_lock_spinning_enable kernel/printk/printk.c:1587 [inline] console_unlock+0x5cd/0x1160 kernel/printk/printk.c:2402 vprintk_emit+0x33d/0x930 kernel/printk/printk.c:1922 vprintk_default+0x28/0x30 kernel/printk/printk.c:1963 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1996 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+0x30b/0xad8 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x17f/0x1c0 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864 arch_local_irq_enable arch/x86/include/asm/paravirt.h:798 [inline] do_int80_syscall_32+0xc6/0x890 arch/x86/entry/common.c:348 entry_INT80_compat+0x74/0x7e arch/x86/entry/entry_64_compat.S:406 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-executor0/24016: #0: 0000000004e467eb ((&wq_watchdog_timer)){+.-.}, at: lockdep_copy_map include/linux/lockdep.h:178 [inline] #0: 0000000004e467eb ((&wq_watchdog_timer)){+.-.}, at: call_timer_fn+0x1db/0x920 kernel/time/timer.c:1316 #1: 0000000094338c32 (rcu_read_lock_sched){....}, at: show_workqueue_state+0x0/0x1d0 kernel/workqueue.c:4423 #2: 000000004488cd6c (&(&pool->lock)->rlock){-.-.}, at: show_workqueue_state.cold.49+0xad0/0x159a kernel/workqueue.c:4557 #3: 00000000fb0f9a1d (console_lock){+.+.}, at: console_trylock_spinning kernel/printk/printk.c:1649 [inline] #3: 00000000fb0f9a1d (console_lock){+.+.}, at: vprintk_emit+0x322/0x930 kernel/printk/printk.c:1921 stack backtrace: CPU: 0 PID: 24016 Comm: syz-executor0 Not tainted 4.19.0-rc8+ #64 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+0x1c4/0x2b4 lib/dump_stack.c:113 print_circular_bug.isra.33.cold.54+0x1bd/0x27d 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+0x33e4/0x4ec0 kernel/locking/lockdep.c:3411 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900 console_lock_spinning_enable kernel/printk/printk.c:1587 [inline] console_unlock+0x5cd/0x1160 kernel/printk/printk.c:2402 vprintk_emit+0x33d/0x930 kernel/printk/printk.c:1922 vprintk_default+0x28/0x30 kernel/printk/printk.c:1963 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 printk+0xa7/0xcf kernel/printk/printk.c:1996 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 Lost 56 message(s)! workqueue events_long: flags=0x0 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=4/256 pending: br_fdb_cleanup, br_fdb_cleanup, br_fdb_cleanup, br_fdb_cleanup workqueue events_power_efficient: flags=0x80 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=3/256 pending: gc_worker, do_cache_clean, check_lifetime workqueue mm_percpu_wq: flags=0x8 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 pending: vmstat_update workqueue kblockd: flags=0x18 pwq 1: cpus=0 node=0 flags=0x0 nice=-20 active=1/256 pending: blk_mq_timeout_work workqueue ipv6_addrconf: flags=0x40008 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1 pending: addrconf_verify_work