I did unplug an USB stick by accident with 3.14.4, the result is thisThis [1] might fix the problem you encountered. I reckon one of your drivers exposes a binary attribute file in a named attribute group, which it tries to remove when being unloaded. However, the path it looks for this attribute file is likely wrong.
warning:
[94414.233882] usb 1-3: USB disconnect, device number 4
[94414.245377] scsi 5:0:0:0: rejecting I/O to offline device
[94414.245383] scsi 5:0:0:0: killing request
[94414.370354] FAT-fs (sdc1): unable to read boot sector to mark fs as dirty
[94414.370393] ------------[ cut here ]------------
[94414.370400] WARNING: CPU: 2 PID: 3619 at fs/sysfs/group.c:216 sysfs_remove_group+0xa1/0xb0()
[94414.370403] sysfs group ffffffff81c50ca0 not found for kobject 'target5:0:0'