INFO: task kworker/0:2:2092 blocked for more than 120 seconds. Not tainted 4.16.0+ #288 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:2 D18728 2092 2 0x80000000 Workqueue: events cgwb_release_workfn Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x8fb/0x1ef0 kernel/sched/core.c:3490 schedule+0xf5/0x430 kernel/sched/core.c:3549 bit_wait+0x18/0x90 kernel/sched/wait_bit.c:197 __wait_on_bit+0x88/0x130 kernel/sched/wait_bit.c:48 out_of_line_wait_on_bit+0x204/0x3a0 kernel/sched/wait_bit.c:63 wait_on_bit include/linux/wait_bit.h:76 [inline] wb_shutdown+0x335/0x430 mm/backing-dev.c:377 cgwb_release_workfn+0x8b/0x622 mm/backing-dev.c:520 process_one_work+0xc97/0x1c40 kernel/workqueue.c:2113 worker_thread+0x1c3/0x1380 kernel/workqueue.c:2247 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411 Showing all locks held in the system: 2 locks held by khungtaskd/877: #0: 00000000d65b3d7f (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000d65b3d7f (rcu_read_lock){....}, at: watchdog+0x1d6/0xd70 kernel/hung_task.c:249 #1: 000000009f7c7b23 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by kworker/0:2/2092: #0: 00000000f492fa43 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000f492fa43 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000f492fa43 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000f492fa43 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 00000000f492fa43 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:619 [inline] #0: 00000000f492fa43 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: 00000000f492fa43 ((wq_completion)"events"){+.+.}, at: process_one_work+0xb83/0x1c40 kernel/workqueue.c:2084 #1: 000000002a814169 ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xbd9/0x1c40 kernel/workqueue.c:2088 2 locks held by getty/4391: #0: 000000003951c638 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000003633d757 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4392: #0: 000000006c974906 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000929a38f0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4393: #0: 00000000f81aa9b3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000f4420dd0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4394: #0: 00000000dd9d56e7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000b52bc871 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4395: #0: 0000000054b94d20 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000005167c0c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4396: #0: 000000006bc83831 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000f226c89d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4397: #0: 00000000932ed2bb (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000cf6b5308 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:6/10173: #0: 0000000002e1db64 ((wq_completion)"%s""netns"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 0000000002e1db64 ((wq_completion)"%s""netns"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 0000000002e1db64 ((wq_completion)"%s""netns"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 0000000002e1db64 ((wq_completion)"%s""netns"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 0000000002e1db64 ((wq_completion)"%s""netns"){+.+.}, at: set_work_data kernel/workqueue.c:619 [inline] #0: 0000000002e1db64 ((wq_completion)"%s""netns"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: 0000000002e1db64 ((wq_completion)"%s""netns"){+.+.}, at: process_one_work+0xb83/0x1c40 kernel/workqueue.c:2084 #1: 000000007c4cf078 (net_cleanup_work){+.+.}, at: process_one_work+0xbd9/0x1c40 kernel/workqueue.c:2088 #2: 000000000971021e (net_mutex){+.+.}, at: cleanup_net+0x242/0xcd0 net/core/net_namespace.c:484 1 lock held by syz-executor6/24122: #0: 00000000fbad8cd3 (&client->ioctl_mutex){+.+.}, at: snd_seq_ioctl+0x1e8/0x3d0 sound/core/seq/seq_clientmgr.c:2143 1 lock held by syz-executor6/24124: #0: 00000000fbad8cd3 (&client->ioctl_mutex){+.+.}, at: snd_seq_ioctl+0x1e8/0x3d0 sound/core/seq/seq_clientmgr.c:2143 1 lock held by syz-executor6/24126: #0: 00000000fbad8cd3 (&client->ioctl_mutex){+.+.}, at: snd_seq_ioctl+0x1e8/0x3d0 sound/core/seq/seq_clientmgr.c:2143 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 877 Comm: khungtaskd Not tainted 4.16.0+ #288 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1a7/0x27d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1e0/0x220 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x123/0x180 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:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x969/0xd70 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 24134 Comm: syz-executor7 Not tainted 4.16.0+ #288 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:mark_lock+0x1b4/0x1450 kernel/locking/lockdep.c:3121 RSP: 0018:ffff88019d4e6188 EFLAGS: 00000046 RAX: dffffc0000000000 RBX: 0000000000000008 RCX: 1ffffffff1321f8c RDX: ffff8801b5c8af00 RSI: 1ffff10036b915e0 RDI: ffffffff8990fc60 RBP: ffff88019d4e62b0 R08: 1ffff10033a9cc35 R09: 0000000000000002 R10: 0000000000000001 R11: fffffbfff1321fad R12: ffff8801b5c8aee0 R13: 0000000000000100 R14: ffffffff8990fc30 R15: 1ffff10033a9cc35 FS: 0000000000000000(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 00000000208feff0 CR3: 00000001a6801000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __lock_acquire+0x638/0x3c30 kernel/locking/lockdep.c:3392 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 rcu_lock_acquire include/linux/rcupdate.h:246 [inline] rcu_read_lock include/linux/rcupdate.h:632 [inline] lock_page_memcg+0x8f/0x320 mm/memcontrol.c:1607 page_remove_file_rmap mm/rmap.c:1213 [inline] page_remove_rmap+0x3b1/0xf40 mm/rmap.c:1298 zap_pte_range mm/memory.c:1337 [inline] zap_pmd_range mm/memory.c:1441 [inline] zap_pud_range mm/memory.c:1470 [inline] zap_p4d_range mm/memory.c:1491 [inline] unmap_page_range+0xfff/0x2330 mm/memory.c:1512 unmap_single_vma+0x15f/0x2d0 mm/memory.c:1557 unmap_vmas+0xf1/0x1b0 mm/memory.c:1587 exit_mmap+0x23a/0x500 mm/mmap.c:3027 __mmput kernel/fork.c:960 [inline] mmput+0x23d/0x700 kernel/fork.c:981 exit_mm kernel/exit.c:544 [inline] do_exit+0x9c5/0x2700 kernel/exit.c:852 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x74c/0x16e0 kernel/signal.c:2469 do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_32_irqs_on arch/x86/entry/common.c:336 [inline] do_fast_syscall_32+0xbe6/0xf9f arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7f42c99 RSP: 002b:00000000f5f3e10c EFLAGS: 00000296 ORIG_RAX: 00000000000000f0 RAX: fffffffffffffe00 RBX: 000000000813af1c RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Code: 49 c1 e6 04 49 81 ee 50 01 00 00 49 81 c6 c0 c3 90 89 49 8d 7e 30 48 b8 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 80 3c 01 00 <0f> 85 24 12 00 00 4d 85 6e 30 74 73 41 be 01 00 00 00 48 b8 00 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.244 msecs