Newbies using slashed in filesystem labels should get an appropriate message from fstab generator instead of just memory exhaustion message. Please look at this one: https://forums.gentoo.org/viewtopic-p-7409746.html
It looks like this was a bug that was fixed a few days after you reported this issue, git bisect found this commit: commit 1d5989fd803d2019de0f6aaaf3cfb1cb2bbc3cdb Author: Dave Reisner Date: Sun Oct 6 18:26:23 2013 -0400 shared/util: fix off-by-one error in tag_to_udev_node Triggered false negatives when encoding a string which needed every character to be escaped, e.g. "LABEL=/".
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