For some reason polkitd keeps the mime.cache opened. There seems to be no other application holding that file open, so I assume it is something polkit specific. Version is sys-auth/polkit-0.99-r1 (on Gentoo) Output from lsof: polkitd 2039 root DEL REG 254,0 692534 /usr/share/mime/mime.cache
This is completely normal for GIO applications. But it's really unnecessary to know the content type.. so I committed http://cgit.freedesktop.org/PolicyKit/commit/?id=78baa4742cf07fb04a9ecab24a068eca0e6ed547 this and, hey presto, that file is no longer mapped.
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