CPU: 0 PID: 17444 Comm: syz-executor1 Not tainted 4.16.0+ #3 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 handle_userfault.cold.32+0x44/0x57 fs/userfaultfd.c:430 INFO: task kworker/0:0:30523 blocked for more than 120 seconds. Not tainted 4.16.0+ #3 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:0 D do_anonymous_page mm/memory.c:3147 [inline] handle_pte_fault mm/memory.c:3961 [inline] __handle_mm_fault+0x34be/0x4150 mm/memory.c:4087 23360 30523 2 0x80000000 Workqueue: events cgwb_release_workfn handle_mm_fault+0x53a/0xc70 mm/memory.c:4124 Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x801/0x1e30 kernel/sched/core.c:3490 __do_page_fault+0x60b/0xe40 arch/x86/mm/fault.c:1399 do_page_fault+0xee/0x8a7 arch/x86/mm/fault.c:1474 page_fault+0x25/0x50 arch/x86/entry/entry_64.S:1159 RIP: 0010:copy_user_generic_unrolled+0x86/0xc0 arch/x86/lib/copy_user_64.S:65 RSP: 0018:ffff8801b57ffce8 EFLAGS: 00010206 RAX: ffffed0036afffae RBX: 0000000000000018 RCX: 0000000000000003 RDX: 0000000000000000 RSI: 0000000020013000 RDI: ffff8801b57ffd58 RBP: ffff8801b57ffd20 R08: ffffed0036afffae R09: ffffed0036afffab R10: ffffed0036afffad R11: ffff8801b57ffd6f R12: 0000000020013018 R13: 0000000020013000 R14: ffff8801b57ffd58 R15: 00007ffffffff000 copy_from_user include/linux/uaccess.h:147 [inline] SYSC_sigaltstack kernel/signal.c:3539 [inline] SyS_sigaltstack+0xae/0x320 kernel/signal.c:3535 schedule+0xef/0x430 kernel/sched/core.c:3549 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x455319 RSP: 002b:00007fe24ecf0c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000083 RAX: ffffffffffffffda RBX: 00007fe24ecf16d4 RCX: 0000000000455319 RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000020013000 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000609 R14: 00000000006fc178 R15: 0000000000000000 FAULT_FLAG_ALLOW_RETRY missing 30 bit_wait+0x18/0x90 kernel/sched/wait_bit.c:197 __wait_on_bit+0xb3/0x130 kernel/sched/wait_bit.c:48 CPU: 0 PID: 17497 Comm: syz-executor1 Not tainted 4.16.0+ #3 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 out_of_line_wait_on_bit+0x204/0x3a0 kernel/sched/wait_bit.c:63 handle_userfault.cold.32+0x44/0x57 fs/userfaultfd.c:430 wait_on_bit include/linux/wait_bit.h:76 [inline] wb_shutdown+0x370/0x470 mm/backing-dev.c:366 do_anonymous_page mm/memory.c:3147 [inline] handle_pte_fault mm/memory.c:3961 [inline] __handle_mm_fault+0x34be/0x4150 mm/memory.c:4087 cgwb_release_workfn+0x87/0x750 mm/backing-dev.c:509 handle_mm_fault+0x53a/0xc70 mm/memory.c:4124 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 __do_page_fault+0x60b/0xe40 arch/x86/mm/fault.c:1399 do_page_fault+0xee/0x8a7 arch/x86/mm/fault.c:1474 page_fault+0x25/0x50 arch/x86/entry/entry_64.S:1159 RIP: 0010:copy_user_generic_unrolled+0x86/0xc0 arch/x86/lib/copy_user_64.S:65 RSP: 0018:ffff8801b7947ce8 EFLAGS: 00010206 RAX: ffffed0036f28fae RBX: 0000000000000018 RCX: 0000000000000003 RDX: 0000000000000000 RSI: 0000000020013000 RDI: ffff8801b7947d58 RBP: ffff8801b7947d20 R08: ffffed0036f28fae R09: ffffed0036f28fab R10: ffffed0036f28fad R11: ffff8801b7947d6f R12: 0000000020013018 R13: 0000000020013000 R14: ffff8801b7947d58 R15: 00007ffffffff000 copy_from_user include/linux/uaccess.h:147 [inline] SYSC_sigaltstack kernel/signal.c:3539 [inline] SyS_sigaltstack+0xae/0x320 kernel/signal.c:3535 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x455319 RSP: 002b:00007fe24eccfc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000083 RAX: ffffffffffffffda RBX: 00007fe24ecd06d4 RCX: 0000000000455319 RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000020013000 RBP: 000000000072bf58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000609 R14: 00000000006fc178 R15: 0000000000000001 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: 00000000b28f14ec (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000b28f14ec (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000d6bbe5a4 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4460: #0: 00000000e22884b3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000013ddc9b8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4461: #0: 000000005f04ec02 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000005d4f8527 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4462: #0: 000000003405dd15 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c3ec63c1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4463: #0: 00000000ec641df5 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000058ea1741 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4464: #0: 00000000f097c053 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c124b7ae (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4465: #0: 00000000f89440e2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000f6071068 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by kworker/0:0/30523: #0: 00000000ffece5e8 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000ffece5e8 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000ffece5e8 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000ffece5e8 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 00000000ffece5e8 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000ffece5e8 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000ffece5e8 ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000fdef1b4a ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by getty/12970: #0: 000000001b7411ee (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000008730ecb6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 888 Comm: khungtaskd Not tainted 4.16.0+ #3 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 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54