for /tmp and /var. This makes the memory discs swap-backed instead
of malloc-backed. A swap-backed memory disc should not be worse
than a malloc-backed one in any scenario because it will start
touching swap only when needed. OTOH, a malloc-backed disc can
starve limited kernel resources and evenually crash the system.
Reflect the change in the rc.conf(5) manpage. Also stop telling
lies there about softupdates: it does not waste disc space, it
just can delay its freeing.
Suggested by: many
PR: kern/87255
MFC after: 1 week
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