R13: 0000000000000001 R14: 00000000007001a0 R15: 0000000000000009
FAT-fs (loop7): bogus number of reserved sectors
FAT-fs (loop7): Can't find a valid FAT filesystem
------------[ cut here ]------------
sysfs group 'loop' not found for kobject 'loop7'
WARNING: CPU: 0 PID: 11480 at fs/sysfs/group.c:235 sysfs_remove_group+0x15b/0x1b0 fs/sysfs/group.c:233
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 11480 Comm: syz-executor7 Not tainted 4.17.0+ #82
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:sysfs_remove_group+0x15b/0x1b0 fs/sysfs/group.c:233
RSP: 0018:ffff8801a8b1f848 EFLAGS: 00010286
RAX: 0000000000000030 RBX: ffffffff892dd3c0 RCX: ffffc90003afe000
RDX: 000000000000b13a RSI: ffffffff81610d61 RDI: ffff8801a8b1f3a8
RBP: ffff8801a8b1f870 R08: ffff8801b180e5c0 R09: 0000000000000006
R10: ffff8801b180e5c0 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8801d2a8aea0 R14: ffffffff8827acc0 R15: ffff8801d2a3f9a8
 loop_sysfs_exit drivers/block/loop.c:820 [inline]
 loop_clr_fd+0x59a/0xc10 drivers/block/loop.c:1074
 lo_ioctl+0x642/0x2130 drivers/block/loop.c:1405
 __blkdev_driver_ioctl block/ioctl.c:303 [inline]
 blkdev_ioctl+0x9b6/0x2020 block/ioctl.c:601
 block_ioctl+0xee/0x130 fs/block_dev.c:1877
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
 __do_sys_ioctl fs/ioctl.c:708 [inline]
 __se_sys_ioctl fs/ioctl.c:706 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455877
RSP: 002b:00007f6e0a5aaba8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000020000000 RCX: 0000000000455877
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000016
RBP: 0000000000000001 R08: 0000000020000240 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015
R13: 0000000000000001 R14: 00000000007001a0 R15: 0000000000000009
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..