INFO: task syz-executor4:5986 blocked for more than 120 seconds. Not tainted 4.4.115-g55a366596 #14 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor4 D ffff8801c8f2f8c8 29576 5986 3793 0x00000002 ffff8801c8f2f8c8 0000000000000000 0000000000000000 0000000000000000 0000000000000001 ffff8801c8f2f800 ffff8801db31fdb8 ffff8801db31fde0 ffff8801db31f4d8 ffff8801d8f94800 ffff8800bbb7c800 0000000000000000 Call Trace: [] schedule+0x7a/0x1b0 kernel/sched/core.c:3353 [] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3386 [] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [] mutex_lock_nested+0x306/0x850 kernel/locking/mutex.c:621 [] odev_release+0x4a/0x70 sound/core/seq/oss/seq_oss.c:151 [] __fput+0x233/0x6d0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x104/0x180 kernel/task_work.c:115 [] exit_task_work include/linux/task_work.h:21 [inline] [] do_exit+0x82a/0x2a10 kernel/exit.c:755 [] do_group_exit+0x108/0x320 kernel/exit.c:885 [] get_signal+0x4f2/0x1550 kernel/signal.c:2317 [] do_signal+0x8b/0x1d40 arch/x86/kernel/signal.c:712 [] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:247 [] prepare_exit_to_usermode arch/x86/entry/common.c:282 [inline] [] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:347 [] int_ret_from_sys_call+0x25/0xa3 INFO: lockdep is turned off. Sending NMI to all CPUs: NMI backtrace for cpu 0 CPU: 0 PID: 485 Comm: khungtaskd Not tainted 4.4.115-g55a366596 #14 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800bb2c1800 task.stack: ffff8800bb3c0000 RIP: 0010:[] [] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline] RIP: 0010:[] [] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline] RIP: 0010:[] [] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline] RIP: 0010:[] [] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69 RSP: 0018:ffff8800bb3c7cb8 EFLAGS: 00000046 RAX: 0000000003000000 RBX: 0000000000000c00 RCX: ffffffff8126a2f2 RDX: 0000000000000c00 RSI: 0000000000000002 RDI: ffffffffff5fb300 RBP: ffff8800bb3c7ce0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: fffffbfff0ad7e2c R12: 0000000000000246 R13: 0000000000000003 R14: ffffffff8426f3a0 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f043ceae9b8 CR3: 00000001d3074000 CR4: 0000000000160670 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffffffff8426f3a0 ffffffff847ef7c0 fffffbfff08fd9ac dffffc0000000000 ffff8801db31bca0 ffff8800bb3c7d00 ffffffff810b99eb ffffffff839f6200 0000000000000003 ffff8800bb3c7d60 ffffffff81d0ecf4 0000000000000001 Call Trace: [] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33 [] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85 [] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 [] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6fa/0xae0 kernel/hung_task.c:238 [] kthread+0x268/0x300 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:506 Code: b3 5f ff f6 c4 10 75 e1 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 74 1a e8 7b 2f 17 00 4c 89 e7 57 9d 0f 1f NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.115-g55a366596 #14 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801d9b49800 task.stack: ffff8801d9b58000 RIP: 0010:[] [] __lock_acquire+0x3b/0x4b50 kernel/locking/lockdep.c:3072 RSP: 0018:ffff8801d9b5fa30 EFLAGS: 00000086 RAX: 0000000000000000 RBX: ffff8801d9b49800 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff8801db319658 RBP: ffff8801d9b5fbd0 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff83844400 R11: ffffffff847ebc38 R12: 0000000000000000 R13: 0000000000000000 R14: ffff8801db319658 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c422e1b000 CR3: 00000001d3074000 CR4: 0000000000160670 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000000 0000000000000001 ffff8801d9b5fac8 0000000000000046 0000000000000000 ffffffff81d65774 0000000000000000 0000000000000000 0000000000000001 ffff8801d9b5fb38 0000000000000046 ffff8801d9b49800 Call Trace: [] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592 [] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:112 [inline] [] _raw_spin_lock_irqsave+0x4e/0x70 kernel/locking/spinlock.c:159 [] lock_hrtimer_base.isra.16+0x75/0x130 kernel/time/hrtimer.c:152 [] hrtimer_try_to_cancel+0xca/0x660 kernel/time/hrtimer.c:1056 [] hrtimer_cancel+0x22/0x40 kernel/time/hrtimer.c:1079 [] tick_nohz_restart+0x1e/0x190 kernel/time/tick-sched.c:559 [] tick_nohz_restart_sched_tick kernel/time/tick-sched.c:726 [inline] [] tick_nohz_idle_exit+0x247/0x3d0 kernel/time/tick-sched.c:946 [] cpu_idle_loop kernel/sched/idle.c:267 [inline] [] cpu_startup_entry+0x2a5/0x8f0 kernel/sched/idle.c:301 [] start_secondary+0x304/0x3e0 arch/x86/kernel/smpboot.c:242 Code: fc ff df 41 56 49 89 fe 41 55 41 54 41 89 f4 53 48 83 e4 f0 48 81 ec 70 01 00 00 48 8b 45 10 48 c7 84 24 90 00 00 00 b3 8a b5 41 <48> c7 84 24 98 00 00 00 e8 1b fb 83 48 c7 84 24 a0 00 00 00 70