INFO: task syz-executor.1:9924 blocked for more than 143 seconds. Not tainted 5.1.0-rc4-next-20190411 #23 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28520 9924 9033 0x00000004 Call Trace: context_switch kernel/sched/core.c:2877 [inline] __schedule+0x817/0x1cc0 kernel/sched/core.c:3518 schedule+0x92/0x180 kernel/sched/core.c:3562 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3620 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0x726/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 snd_seq_kernel_client_ctl+0xe5/0x170 sound/core/seq/seq_clientmgr.c:2345 snd_seq_oss_control sound/core/seq/oss/seq_oss_device.h:157 [inline] snd_seq_oss_writeq_clear+0xe0/0x140 sound/core/seq/oss/seq_oss_writeq.c:85 snd_seq_oss_writeq_delete+0x20/0x40 sound/core/seq/oss/seq_oss_writeq.c:69 free_devinfo+0x66/0xc0 sound/core/seq/oss/seq_oss_init.c:406 port_delete+0xe8/0x1c0 sound/core/seq/seq_ports.c:272 snd_seq_delete_port+0x266/0x330 sound/core/seq/seq_ports.c:301 snd_seq_ioctl_delete_port+0xba/0x190 sound/core/seq/seq_clientmgr.c:1321 snd_seq_kernel_client_ctl+0x112/0x170 sound/core/seq/seq_clientmgr.c:2346 snd_seq_event_port_detach+0xba/0x100 sound/core/seq/seq_ports.c:705 delete_port+0x87/0xd0 sound/core/seq/oss/seq_oss_init.c:354 snd_seq_oss_release+0xf5/0x150 sound/core/seq/oss/seq_oss_init.c:433 odev_release+0x54/0x80 sound/core/seq/oss/seq_oss.c:153 __fput+0x2e5/0x8d0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x14a/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:166 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4129e1 Code: e8 34 99 01 00 e9 45 fe ff ff 4c 8b 86 80 00 00 00 4c 39 c3 72 08 48 85 f6 e9 32 fd ff ff 44 0f b6 46 64 41 80 f8 01 74 08 48 <85> f6 e9 1f fd ff ff 0f b7 56 5e 66 85 d2 74 6a 48 29 fb 0f b7 d2 RSP: 002b:00007fff907afd00 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000006 RCX: 00000000004129e1 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000073c900 R08: 00000000f8309d34 R09: 00000000f8309d38 R10: 00007fff907afdd0 R11: 0000000000000293 R12: 0000000000000001 R13: 000000000073c900 R14: 00000000000218e5 R15: 000000000073bfac INFO: lockdep is turned off. NMI backtrace for cpu 0 CPU: 0 PID: 1044 Comm: khungtaskd Not tainted 5.1.0-rc4-next-20190411 #23 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+0x172/0x1f0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1be/0x236 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0x9b7/0xec0 kernel/hung_task.c:288 kthread+0x357/0x430 kernel/kthread.c:254 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: