ksm: enable KSM page migration
Migration of KSM pages is now safe: remove the PageKsm restrictions from mempolicy.c and migrate.c. But keep PageKsm out of __unmap_and_move()'s anon_vma contortions, which are irrelevant to KSM: it looks as if that code was preventing hotremove migration of KSM pages, unless they happened to be in swapcache. There is some question as to whether enforcing a NUMA mempolicy migration ought to migrate KSM pages, mapped into entirely unrelated processes; but moving page_mapcount > 1 is only permitted with MPOL_MF_MOVE_ALL anyway, and it seems reasonable to assume that you wouldn't set MADV_MERGEABLE on any area where this is a worry. Signed-off-by:Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
parent
4146d2d6
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