INFO: task kworker/1:0:18 blocked for more than 120 seconds. Not tainted 4.16.0+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:0 D23032 18 2 0x80000000 Workqueue: events cgwb_release_workfn Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x807/0x1e40 kernel/sched/core.c:3490 schedule+0xef/0x430 kernel/sched/core.c:3549 bit_wait+0x18/0x90 kernel/sched/wait_bit.c:197 __wait_on_bit+0xb3/0x130 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+0x370/0x470 mm/backing-dev.c:377 cgwb_release_workfn+0x87/0x750 mm/backing-dev.c:520 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 kthread+0x345/0x410 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 kworker/1:0/18: #0: 000000007a33aa73 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 000000007a33aa73 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000007a33aa73 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000007a33aa73 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 000000007a33aa73 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000007a33aa73 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000007a33aa73 ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 000000005179b10f ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by khungtaskd/882: #0: 00000000cea1b09d (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000cea1b09d (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 000000004f373307 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4435: #0: 00000000c5c15b8e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000000af79818 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4436: #0: 000000000a63a897 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000069501568 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4437: #0: 00000000399d1364 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000000c3f1b7f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4438: #0: 00000000fcbf4423 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000008cc442ea (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4439: #0: 000000002a3f6744 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ec32038d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4440: #0: 00000000c501e491 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000068183349 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4441: #0: 000000001886bda9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000bfee6f45 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor0/4510: #0: 000000008fbd8120 (loop_index_mutex){+.+.}, at: loop_probe+0x7c/0x1c0 drivers/block/loop.c:1935 3 locks held by kworker/u4:5/6103: #0: 00000000e078c5a7 ((wq_completion)"%s""netns"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000e078c5a7 ((wq_completion)"%s""netns"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000e078c5a7 ((wq_completion)"%s""netns"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000e078c5a7 ((wq_completion)"%s""netns"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 00000000e078c5a7 ((wq_completion)"%s""netns"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000e078c5a7 ((wq_completion)"%s""netns"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000e078c5a7 ((wq_completion)"%s""netns"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 0000000056ef847a (net_cleanup_work){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 #2: 0000000091feac34 (pernet_ops_rwsem){++++}, at: cleanup_net+0x11a/0xb20 net/core/net_namespace.c:490 2 locks held by syz-executor3/16761: #0: 00000000273dd7c3 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x193/0x13a0 fs/block_dev.c:1458 #1: 000000008fbd8120 (loop_index_mutex){+.+.}, at: lo_open+0x1b/0xb0 drivers/block/loop.c:1588 1 lock held by syz-executor4/20470: #0: 00000000a4e7d285 (sk_lock-AF_INET6){+.+.}, at: lock_sock include/net/sock.h:1469 [inline] #0: 00000000a4e7d285 (sk_lock-AF_INET6){+.+.}, at: sctp_setsockopt+0x33e/0x6dd0 net/sctp/socket.c:4158 1 lock held by syz-executor6/20476: #0: 000000008fbd8120 (loop_index_mutex){+.+.}, at: loop_control_ioctl+0x8c/0x500 drivers/block/loop.c:1955 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 882 Comm: khungtaskd Not tainted 4.16.0+ #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+0x1b9/0x294 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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+0xc10/0xf60 kernel/hung_task.c:249 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 20501 Comm: syz-executor1 Not tainted 4.16.0+ #4 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:pte_flags arch/x86/include/asm/pgtable_types.h:425 [inline] RIP: 0010:pte_present arch/x86/include/asm/pgtable.h:648 [inline] RIP: 0010:zap_pte_range mm/memory.c:1307 [inline] RIP: 0010:zap_pmd_range mm/memory.c:1441 [inline] RIP: 0010:zap_pud_range mm/memory.c:1470 [inline] RIP: 0010:zap_p4d_range mm/memory.c:1491 [inline] RIP: 0010:unmap_page_range+0xa1d/0x2200 mm/memory.c:1512 RSP: 0018:ffff88019dd1eba8 EFLAGS: 00000293 RAX: ffff8801b20de580 RBX: ffff8801a83cf1e8 RCX: ffffffff81a45bff RDX: 0000000000000000 RSI: ffffffff81a45c0d RDI: 0000000000000007 RBP: ffff88019dd1f040 R08: ffff8801b20de580 R09: fffff94000e59c03 R10: fffff94000e59c03 R11: ffffea00072ce01b R12: 80000001cbc20007 R13: 80000001cbc20007 R14: dffffc0000000000 R15: 00007fae6b915000 FS: 00007fae69914700(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f873e67adb8 CR3: 00000001b2f5f000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: unmap_single_vma+0x1a0/0x310 mm/memory.c:1557 unmap_vmas+0x120/0x1f0 mm/memory.c:1587 exit_mmap+0x265/0x570 mm/mmap.c:3027 __mmput kernel/fork.c:960 [inline] mmput+0x251/0x610 kernel/fork.c:981 exit_mm kernel/exit.c:544 [inline] do_exit+0xe98/0x2730 kernel/exit.c:852 do_group_exit+0x16f/0x430 kernel/exit.c:968 get_signal+0x886/0x1960 kernel/signal.c:2469 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x28a/0x310 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_64+0x792/0x9d0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x455259 RSP: 002b:00007fae69913c88 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007fae699146d4 RCX: 0000000000455259 RDX: 0000000000000018 RSI: 0000000000000001 RDI: 000000000072becc RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000000a8 R14: 00000000006f4060 R15: 0000000000000000 Code: 3c 30 00 0f 85 83 13 00 00 4c 8b 23 31 ff 4d 89 e5 49 83 e5 9f 4c 89 ee e8 71 50 d2 ff 4d 85 ed 0f 84 0c 09 00 00 e8 33 4f d2 ff <45> 89 e5 31 ff 41 81 e5 01 01 00 00 44 89 ee e8 2f 50 d2 ff 45 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.180 msecs