INFO: task kworker/0:3:2104 blocked for more than 120 seconds. Not tainted 4.17.0-rc2+ #16 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:3 D19800 2104 2 0x80000000 Workqueue: events cgwb_release_workfn Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x801/0x1e30 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:366 cgwb_release_workfn+0x87/0x750 mm/backing-dev.c:509 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:412 Showing all locks held in the system: 2 locks held by khungtaskd/891: #0: 00000000fe99ed50 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000fe99ed50 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 000000008c212f60 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 1 lock held by khugepaged/897: #0: 000000004bfcc389 (&mm->mmap_sem){++++}, at: collapse_huge_page+0x2b1/0x2110 mm/khugepaged.c:1006 2 locks held by kworker/0:3/2104: #0: 0000000076933e0c ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 0000000076933e0c ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 0000000076933e0c ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 0000000076933e0c ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 0000000076933e0c ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 0000000076933e0c ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 0000000076933e0c ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000532bb41e ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by rs:main Q:Reg/4394: #0: 00000000a4a0cd78 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 #1: 00000000ecc2adc0 (sb_writers#4){++++}, at: file_start_write include/linux/fs.h:2718 [inline] #1: 00000000ecc2adc0 (sb_writers#4){++++}, at: vfs_write+0x452/0x560 fs/read_write.c:548 1 lock held by rsyslogd/4396: #0: 00000000197a968a (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 2 locks held by getty/4486: #0: 0000000030f7d1a7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000002d8d7152 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4487: #0: 00000000277ef0a9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c938ba48 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4488: #0: 00000000e348ddee (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000522edbc6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4489: #0: 00000000a2c7a569 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000768ee6fb (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4490: #0: 00000000321cb1aa (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000cd488419 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4491: #0: 0000000024750cf7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000000ce3df76 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4492: #0: 00000000f783fa1f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000a1a9ac8f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by syz-fuzzer/4510: #0: 000000004bfcc389 (&mm->mmap_sem){++++}, at: __do_page_fault+0x381/0xe40 arch/x86/mm/fault.c:1328 #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: sb_start_pagefault include/linux/fs.h:1579 [inline] #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: ext4_page_mkwrite+0x1c8/0x1420 fs/ext4/inode.c:6094 2 locks held by syz-fuzzer/4511: #0: 000000004bfcc389 (&mm->mmap_sem){++++}, at: __do_page_fault+0x381/0xe40 arch/x86/mm/fault.c:1328 #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: sb_start_pagefault include/linux/fs.h:1579 [inline] #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: ext4_page_mkwrite+0x1c8/0x1420 fs/ext4/inode.c:6094 1 lock held by syz-executor1/4563: #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1550 [inline] #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 1 lock held by syz-executor4/4566: #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1550 [inline] #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 2 locks held by syz-executor0/14633: #0: 000000002b4babf2 (&mm->mmap_sem){++++}, at: __do_page_fault+0x381/0xe40 arch/x86/mm/fault.c:1328 #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: sb_start_pagefault include/linux/fs.h:1579 [inline] #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: ext4_page_mkwrite+0x1c8/0x1420 fs/ext4/inode.c:6094 1 lock held by syz-executor3/14637: #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1550 [inline] #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 2 locks held by syz-executor7/14640: #0: 00000000026b2e46 (&mm->mmap_sem){++++}, at: __do_page_fault+0x381/0xe40 arch/x86/mm/fault.c:1328 #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: sb_start_pagefault include/linux/fs.h:1579 [inline] #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: ext4_page_mkwrite+0x1c8/0x1420 fs/ext4/inode.c:6094 2 locks held by syz-executor5/14641: #0: 00000000b9c2482d (&mm->mmap_sem){++++}, at: __do_page_fault+0x381/0xe40 arch/x86/mm/fault.c:1328 #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: sb_start_pagefault include/linux/fs.h:1579 [inline] #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: ext4_page_mkwrite+0x1c8/0x1420 fs/ext4/inode.c:6094 1 lock held by syz-executor5/14646: #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1550 [inline] #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 2 locks held by syz-executor2/14643: #0: 000000002af30f6e (&mm->mmap_sem){++++}, at: __do_page_fault+0x381/0xe40 arch/x86/mm/fault.c:1328 #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: sb_start_pagefault include/linux/fs.h:1579 [inline] #1: 000000000f5dbb7f (sb_pagefaults){++++}, at: ext4_page_mkwrite+0x1c8/0x1420 fs/ext4/inode.c:6094 1 lock held by syz-executor6/14647: #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1550 [inline] #0: 00000000ecc2adc0 (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 891 Comm: khungtaskd Not tainted 4.17.0-rc2+ #16 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:412 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.17.0-rc2+ #16 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:31 [inline] RIP: 0010:atomic_read include/asm-generic/atomic-instrumented.h:22 [inline] RIP: 0010:got_nohz_idle_kick kernel/sched/core.c:586 [inline] RIP: 0010:scheduler_ipi+0x1bb/0xa30 kernel/sched/core.c:1752 RSP: 0018:ffff8801dae07cf0 EFLAGS: 00000046 RAX: ffff8801dae07d28 RBX: 1ffff1003b5c0fa1 RCX: ffffffff8152ff00 RDX: dffffc0000000000 RSI: ffff8801dae07d28 RDI: ffff8801dae2c608 RBP: ffff8801dae07e90 R08: ffff8801dae2c608 R09: ffffed003b5c58c1 R10: ffffed003b5c58c1 R11: ffff8801dae2c60b R12: 000000000002c580 R13: ffff8801dae2c580 R14: ffff8801dae07e68 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001e93000 CR3: 00000001b0b81000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: smp_reschedule_interrupt+0xed/0x660 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:887 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff88c07bc0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff1180f7b RCX: 0000000000000000 RDX: 1ffffffff11a3160 RSI: 0000000000000001 RDI: ffffffff88d18b00 RBP: ffffffff88c07bc0 R08: ffffed003b5c46c3 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff88c07c78 R14: ffffffff897beda0 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0xc2/0x440 arch/x86/kernel/process.c:354 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:345 default_idle_call+0x6d/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x395/0x560 kernel/sched/idle.c:262 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:368 rest_init+0xe1/0xe4 init/main.c:441 start_kernel+0x906/0x92d init/main.c:737 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:445 x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:426 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242 Code: 00 4c 89 c7 4c 89 85 70 fe ff ff e8 50 82 62 00 49 8d 86 c0 fe ff ff 4c 8b 85 70 fe ff ff 48 ba 00 00 00 00 00 fc ff df 48 89 c6 <48> 8b 8d 68 fe ff ff 48 c1 ee 03 c6 04 16 04 4c 89 c6 48 c1 ee