F2FS-fs (loop4): Can't find valid F2FS filesystem in 2th superblock
F2FS-fs (loop4): Magic Mismatch, valid(0xf2f52010) - read(0x0)
F2FS-fs (loop4): Can't find valid F2FS filesystem in 1th superblock
F2FS-fs (loop4): Magic Mismatch, valid(0xf2f52010) - read(0x0)
F2FS-fs (loop4): Can't find valid F2FS filesystem in 2th superblock
WARNING: CPU: 0 PID: 27196 at sound/core/seq/seq_ports.c:276 port_delete+0x16e/0x1b0 sound/core/seq/seq_ports.c:276
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 27196 Comm: syz-executor6 Not tainted 4.18.0-rc5+ #153
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+0x1c9/0x2b4 lib/dump_stack.c:113
 panic+0x238/0x4e7 kernel/panic.c:184
 __warn.cold.8+0x163/0x1ba kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:port_delete+0x16e/0x1b0 sound/core/seq/seq_ports.c:276
Code: 00 00 31 ff 44 89 e6 e8 a0 ff 9d fb 45 85 e4 75 14 e8 86 fe 9d fb 48 89 df e8 de b1 db fb 31 c0 5b 41 5c 5d c3 e8 72 fe 9d fb <0f> 0b eb e3 e8 69 fe 9d fb 0f 0b eb 9b e8 60 dd db fb eb bd e8 59 
RSP: 0018:ffff88019546f8d0 EFLAGS: 00010293
RAX: ffff8801976aa600 RBX: ffff8801c6759200 RCX: ffffffff85de0cf0
RDX: 0000000000000000 RSI: ffffffff85de0d0e RDI: 0000000000000005
RBP: ffff88019546f8e0 R08: ffff8801976aa600 R09: 0000000000000006
R10: ffff8801976aa600 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8801c6759250 R14: 1ffff10032a8df28 R15: ffff880194a5c950
 snd_seq_delete_port+0x3cb/0x4a0 sound/core/seq/seq_ports.c:303
 snd_seq_ioctl_delete_port+0xba/0x190 sound/core/seq/seq_clientmgr.c:1325
 snd_seq_kernel_client_ctl+0x15a/0x190 sound/core/seq/seq_clientmgr.c:2361
 snd_seq_event_port_detach+0xfb/0x160 sound/core/seq/seq_ports.c:705
 delete_port+0x7d/0xc0 sound/core/seq/oss/seq_oss_init.c:354
 snd_seq_oss_release+0xf2/0x130 sound/core/seq/oss/seq_oss_init.c:433
 odev_release+0x52/0x70 sound/core/seq/oss/seq_oss.c:153
 __fput+0x355/0x8b0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:192 [inline]
 exit_to_usermode_loop+0x313/0x370 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+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x40fb91
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 19 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 
RSP: 002b:00007ffe0f5d68f0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000015 RCX: 000000000040fb91
RDX: 0000000000000000 RSI: 0000000000731498 RDI: 0000000000000014
RBP: 0000000000000013 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffe0f5d6770 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ffe0f5d6fa0 R15: 00000000007034c0
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..