I've mentioned this a couple of times in posts. After talking to Rik
and Stephen, it seems that this it totally normal though I still don't
completely understand it, and is related in some way to swap-cache.
Now I think Stephen agrees that this at least needs to be documented and
reported differently by the system so that 'free' doesn't report swap
and cache being used when they aren't really (at least in the case of
the swap, reporting it used is bogus). It appears to be due to lazy
cleanup of swap cached pages.
The one thing that actually breaks with this effect (ignoring the
worried sysadmins!) is that vm_enough_memory() can't tell that the swap
isn't really used and thus denies otherwise acceptable requests for
memory. Once we fix this it's just strange, not broken.
(Stephen - did I get this straight?).
Neil
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