mount: mounting /dev/block/vold/179:98 on /data/sdext2 failed: Device or resource busy When I open Link2SD, it asks to recreate mount scripts: I use ext4. After a reboot, when I open the linked application, it gets stuck and black screen till reboot.

I use ext4 as the 2nd partition, but it shows ext2 in Link2SD, and all my applications are now stuck. 

mount: mounting /dev/block/vold/179:98 on /data/sdext2 failed: Device or resource busy


How to fix this?
check with mount the mount points for /dev/block/vold/179:98 . umount the according mount points to free the device. Beware there could be damage if you interrupt a writting process