On login to EC2 (Ubuntu) instance, I see
*** /dev/xvda1 should be checked for errors ***
fsck /dev/xvda1 because it is mounted, and
sudo umount /dev/xvda1 fails because it is in use.
jbd2/xvda 172 root cwd DIR 202,1 4096 2 / jbd2/xvda 172 root rtd DIR 202,1 4096 2 / jbd2/xvda 172 root txt unknown /proc/172/exe
kill -SIGKILL 172 is ineffective.
What to do?