quoted

There are a couple of special cases that might be feasible without making
an ungodly mess. PTE pages spring to mind (particularly as they can be
in highmem too). They should be reasonably easy to move (assuming we can
use rmap to track them back to the process they belong to to lock them ...
hmmm ....)

We don't do any pte page reclaim at any time other than process exit and
there are plenty of pte pages we can just plain free anyway.  Anthing
that's completely mapping page cache, for instance.

In the replacement case, taking mm->page_table_lock, doing the copy, and
replacing the pointer from the pmd should be all that it takes.  But, I
wonder if we could miss any sets of the pte dirty bit this way...

As long as we make sure the process doesn't run during the move, I don't
see why it'd be a problem. But I am less than convinced that rmap will
lead us back from the PTE page to the mm, at least w/o modification.

M.

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