sysfs: cannot create duplicate filename '/fs/ext4/mmcblk0p1'
(call trace omitted)
kobject_add_internal failed for mmcblk0p1 with -EEXIST, don't try to register things with the same name in the same directory.
EXT4-fs (mmcblk0p1): mount failed

What I believe is happening is that when clicking mount in Thunar, the mount attempt fails because the sysfs entry "directory" /sys/fs/ext4/mmcblk0p1 already exists.

If I try to mount from the command line it fails in the same way. (File exists.)
Unmounting from the command line fails, as the device obviously isn't mounted anywhere.

How do I get /sys/fs/ext4 in sync with what is actually mounted?
Is there a way to make suspend unmount the card correctly, or not unmount it at all?