INFO: task kworker/1:5:13176 blocked for more than 120 seconds. Not tainted 4.16.0+ #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:5 D23832 13176 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:411 Showing all locks held in the system: 2 locks held by khungtaskd/888: #0: 00000000fa00c439 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000fa00c439 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 000000006f60ebb4 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4446: #0: 00000000555e3aed (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000df7c4ae8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4447: #0: 00000000ab3ae4ea (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000fddce3c5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4448: #0: 00000000cca81699 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000cf91919a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4449: #0: 00000000a1e3de2e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000003e557ef1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4450: #0: 00000000f7d2f835 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006245cf88 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4451: #0: 000000009f099a38 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ebabed44 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4452: #0: 00000000734c2fdb (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000016fa0dc8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by kworker/1:5/13176: #0: 000000008462a3a2 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 000000008462a3a2 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000008462a3a2 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000008462a3a2 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 000000008462a3a2 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000008462a3a2 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000008462a3a2 ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000f76c873f ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by syz-executor0/25301: #0: 000000000b181681 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000005fbfbda0 (&tty->atomic_write_lock){+.+.}, at: tty_write_lock+0x23/0x90 drivers/tty/tty_io.c:884 2 locks held by syz-executor0/25344: #0: 0000000002b8ecb6 (&tty->legacy_mutex){+.+.}, at: tty_lock+0x70/0xa0 drivers/tty/tty_mutex.c:19 #1: 000000000b181681 (&tty->ldisc_sem){++++}, at: ldsem_down_write+0x37/0x40 drivers/tty/tty_ldsem.c:391 2 locks held by syz-executor1/25345: #0: 000000003f570e94 (&tty->legacy_mutex){+.+.}, at: tty_lock+0x70/0xa0 drivers/tty/tty_mutex.c:19 #1: 00000000027fd183 (&tty->ldisc_sem){++++}, at: ldsem_down_write+0x37/0x40 drivers/tty/tty_ldsem.c:391 1 lock held by syz-executor7/25331: #0: 00000000071c7fee (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000071c7fee (&pipe->mutex/1){+.+.}, at: pipe_write+0xc0/0xeb0 fs/pipe.c:366 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 888 Comm: khungtaskd Not tainted 4.16.0+ #1 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 25347 Comm: syz-executor0 Not tainted 4.16.0+ #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:69 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x26/0x50 kernel/kcov.c:101 RSP: 0018:ffff88019b62ee60 EFLAGS: 00000246 RAX: ffff8801ab05c240 RBX: dffffc0000000000 RCX: ffffffff81ab6d29 RDX: 0000000000000000 RSI: ffffffff81ab6aa4 RDI: 0000000000000004 RBP: ffff88019b62ee60 R08: ffff8801ab05c240 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffea0007270b40 R13: 00000000000001b0 R14: ffff8801af087438 R15: 0000000000000085 FS: 00007f2a5e372700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f44c73e9db8 CR3: 00000001a1c05000 CR4: 00000000001426e0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: free_pages_and_swap_cache+0xe4/0x4f0 mm/swap_state.c:321 tlb_flush_mmu_free+0xc3/0x160 mm/memory.c:259 tlb_flush_mmu mm/memory.c:268 [inline] arch_tlb_finish_mmu+0xad/0x170 mm/memory.c:283 tlb_finish_mmu+0x139/0x1e0 mm/memory.c:433 exit_mmap+0x2db/0x570 mm/mmap.c:3058 __mmput kernel/fork.c:962 [inline] mmput+0x251/0x610 kernel/fork.c:983 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: 0033:0x455279 RSP: 002b:00007f2a5e371ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000072c038 RCX: 0000000000455279 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072c038 RBP: 000000000072c038 R08: 0000000000000000 R09: 000000000072c010 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000a3e81f R14: 00007f2a5e3729c0 R15: 0000000000000002 Code: 08 5d c3 66 90 55 65 48 8b 04 25 c0 ed 01 00 65 8b 15 3f bc 8a 7e 48 89 e5 81 e2 00 01 1f 00 48 8b 75 08 75 2b 8b 90 78 12 00 00 <83> fa 02 75 20 48 8b 88 80 12 00 00 8b 80 7c 12 00 00 48 8b 11 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.032 msecs