Run a full fsck(8). Preen mode only checks a couple of things. And make sure it actually fixes any errors it finds. It sounds like it's not fixing things and therefor the filesystem is still dirty.Notably, I ran fsck -p before mount -uw /
Code:
-p Enter preen mode. In preen mode, only a restricted class of
innocuous file system inconsistencies will be corrected. If
unexpected inconsistencies caused by hardware or software
failures are encountered, the check program will exit with a
failure. See the manual pages for the individual check programs
for a list of the sorts of failures that they correct when
running in preen mode.