kobject_add_internal failed for mime_type& with -EEXIST, don't try to register things with the same name in the same directory.
WARNING: CPU: 1 PID: 10649 at lib/kobject.c:238 kobject_add_internal+0x8e0/0xba0 lib/kobject.c:236
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 10649 Comm: syz-executor3 Not tainted 4.17.0-rc1+ #6
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
 panic+0x22f/0x4de kernel/panic.c:184
 __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:kobject_add_internal+0x8e0/0xba0 lib/kobject.c:236
RSP: 0018:ffff8801844974a0 EFLAGS: 00010282
RAX: 000000000000007f RBX: ffff8801aeb60cd0 RCX: ffffc90001b9e000
RDX: 0000000000040000 RSI: ffffffff8160f451 RDI: ffff880184497000
RBP: ffff880184497598 R08: ffff8801d98ec5c0 R09: 0000000000000006
R10: ffff8801d98ec5c0 R11: 0000000000000000 R12: 00000000ffffffef
R13: ffff8801d423e148 R14: 1ffff10030892e9e R15: ffff8801d423e100
 kobject_add_varg lib/kobject.c:364 [inline]
 kobject_init_and_add+0xed/0x130 lib/kobject.c:435
 gfs2_sys_fs_add+0x1ff/0x500 fs/gfs2/sys.c:652
 fill_super+0x8c9/0x1a40 fs/gfs2/ops_fstype.c:1118
 gfs2_mount+0x5e6/0x712 fs/gfs2/ops_fstype.c:1321
 mount_fs+0xae/0x328 fs/super.c:1268
 vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:1027 [inline]
 do_new_mount fs/namespace.c:2517 [inline]
 do_mount+0x564/0x3070 fs/namespace.c:2847
 ksys_mount+0x12d/0x140 fs/namespace.c:3063
 __do_sys_mount fs/namespace.c:3077 [inline]
 __se_sys_mount fs/namespace.c:3074 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3074
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457d5a
RSP: 002b:00007f92b4a27bb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000040 RCX: 0000000000457d5a
RDX: 0000000020000040 RSI: 0000000020000080 RDI: 00007f92b4a27c00
RBP: 0000000000000001 R08: 0000000020000300 R09: 0000000020000040
R10: 00000000020104c0 R11: 0000000000000246 R12: 0000000000000014
R13: 000000000000066b R14: 00000000006fcaa8 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..