syzbot

INFO: task syz-executor4
:5273 blocked for more than 120 seconds.
      Not tainted 4.4.115-g0e9bcc1 #12
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4
 ffff8801cb6c7368 0000000000000000 0000000000000000 0000000000000000
 0000000000000001 ffff8801cb6c7300 ffff8801db21fdb8 ffff8801db21fde0
 ffff8801db21f4d8 ffff8800ae098000 ffff8800af6e6000 0000000000000000
Call Trace:
 [<ffffffff837663ca>] schedule+0x7a/0x1b0 kernel/sched/core.c:3353
 [<ffffffff83766bc3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3386
 [<ffffffff8376b186>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8376b186>] mutex_lock_nested+0x306/0x850 kernel/locking/mutex.c:621
 [<ffffffff82d2ae0d>] snd_seq_do_ioctl+0x15d/0x1b0 sound/core/seq/seq_clientmgr.c:2214
 [<ffffffff82d2af37>] snd_seq_kernel_client_ctl+0xd7/0x150 sound/core/seq/seq_clientmgr.c:2432
 [<ffffffff82d541d0>] snd_seq_oss_control sound/core/seq/oss/seq_oss_device.h:157 [inline]
 [<ffffffff82d541d0>] snd_seq_oss_writeq_clear+0xe0/0x140 sound/core/seq/oss/seq_oss_writeq.c:84
 [<ffffffff82d5424f>] snd_seq_oss_writeq_delete+0x1f/0x30 sound/core/seq/oss/seq_oss_writeq.c:68
 [<ffffffff82d42df1>] free_devinfo+0x61/0xb0 sound/core/seq/oss/seq_oss_init.c:406
 [<ffffffff82d3d095>] port_delete+0xd5/0x110 sound/core/seq/seq_ports.c:273
 [<ffffffff82d3d993>] snd_seq_delete_port+0x1c3/0x200 sound/core/seq/seq_ports.c:303
 [<ffffffff82d291c2>] snd_seq_ioctl_delete_port+0xf2/0x1d0 sound/core/seq/seq_clientmgr.c:1326
 [<ffffffff82d2ae32>] snd_seq_do_ioctl+0x182/0x1b0 sound/core/seq/seq_clientmgr.c:2215
 [<ffffffff82d2af37>] snd_seq_kernel_client_ctl+0xd7/0x150 sound/core/seq/seq_clientmgr.c:2432
 [<ffffffff82d3bddf>] snd_seq_event_port_detach+0xaf/0x100 sound/core/seq/seq_ports.c:706
 [<ffffffff82d42eb3>] delete_port+0x73/0xb0 sound/core/seq/oss/seq_oss_init.c:354
 [<ffffffff82d44064>] snd_seq_oss_release+0xe4/0x130 sound/core/seq/oss/seq_oss_init.c:433
 [<ffffffff82d42802>] odev_release+0x52/0x70 sound/core/seq/oss/seq_oss.c:152
 [<ffffffff815236a3>] __fput+0x233/0x6d0 fs/file_table.c:208
 [<ffffffff81523bc5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118b9e4>] task_work_run+0x104/0x180 kernel/task_work.c:115
 [<ffffffff81132f8a>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81132f8a>] do_exit+0x82a/0x2a10 kernel/exit.c:755
 [<ffffffff81139428>] do_group_exit+0x108/0x320 kernel/exit.c:885
 [<ffffffff8115c882>] get_signal+0x4f2/0x1550 kernel/signal.c:2317
 [<ffffffff8100e7fb>] do_signal+0x8b/0x1d40 arch/x86/kernel/signal.c:712
 [<ffffffff810035fa>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:247
 [<ffffffff81007067>] prepare_exit_to_usermode arch/x86/entry/common.c:282 [inline]
 [<ffffffff81007067>] syscall_return_slowpath arch/x86/entry/common.c:347 [inline]
 [<ffffffff81007067>] do_syscall_32_irqs_on arch/x86/entry/common.c:396 [inline]
 [<ffffffff81007067>] do_fast_syscall_32+0x607/0x890 arch/x86/entry/common.c:457
 [<ffffffff83775eaa>] sysenter_flags_fixed+0xd/0x17
INFO: lockdep is turned off.
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.115-g0e9bcc1 #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84217840 task.stack: ffffffff84200000
RIP: 0010:[<ffffffff810d0536>]  [<ffffffff810d0536>] native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
RSP: 0018:ffffffff84207dc0  EFLAGS: 00000246
RAX: 0000000000000003 RBX: ffffffff847dd8c8 RCX: ffffffff81d63b5b
RDX: 0000000000000004 RSI: ffffffff839fe320 RDI: ffffffff84418180
RBP: ffffffff84207dc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 1ffffffff0840f86 R12: 0000000000000000
R13: fffffbfff070887c R14: ffffffff847ebc38 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c42682d000 CR3: 00000001cbad0000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff84207df8 ffffffff81027ed5 ffffffff84208000 ffffffff847dd8c8
 fffffbfff070887c ffffffff847ebc38 0000000000000000 ffffffff84207e08
 ffffffff8102944a ffffffff84207e20 ffffffff81221468 dffffc0000000000
Call Trace:
 [<ffffffff81027ed5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81027ed5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290
 [<ffffffff8102944a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:281
 [<ffffffff81221468>] default_idle_call+0x48/0x70 kernel/sched/idle.c:93
 [<ffffffff81221b6d>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff81221b6d>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff81221b6d>] cpu_startup_entry+0x5fd/0x8f0 kernel/sched/idle.c:301
 [<ffffffff83761459>] rest_init+0x189/0x190 init/main.c:410
 [<ffffffff84821811>] start_kernel+0x6b9/0x6ee init/main.c:682
 [<ffffffff84820312>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84820454>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:185
Code: 00 00 00 00 00 55 48 89 e5 fa 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb f4 <5d> c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 f4 5d c3 66 0f 1f 84 
NMI backtrace for cpu 1
CPU: 1 PID: 484 Comm: khungtaskd Not tainted 4.4.115-g0e9bcc1 #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d8f56000 task.stack: ffff8800bad18000
RIP: 0010:[<ffffffff810c3eb7>]  [<ffffffff810c3eb7>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3eb7>]  [<ffffffff810c3eb7>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3eb7>]  [<ffffffff810c3eb7>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3eb7>]  [<ffffffff810c3eb7>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bad1fcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: ffffffff8126a292
RDX: 0000000000000c00 RSI: 0000000000000002 RDI: ffffffffff5fb300
RBP: ffff8800bad1fce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: fffffbfff0ad7e2c R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f3a0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c4217efc00 CR3: 00000001cbad0000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f3a0 ffffffff847ef7c0 fffffbfff08fd9ac dffffc0000000000
 ffff8801db31bca0 ffff8800bad1fd00 ffffffff810b99eb ffffffff839f61c0
 0000000000000003 ffff8800bad1fd60 ffffffff81d0ed14 ffffffff839fe320
Call Trace:
 [<ffffffff810b99eb>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d0ed14>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9a84>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81368cca>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81368cca>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81368cca>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81368cca>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff811907e8>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83774945>] 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 1b 2f 17 00 4c 89 e7 57 9d 0f 1f