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authorHugh Dickins <hughd@google.com>2013-02-22 16:35:13 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-23 17:50:19 -0800
commitb79bc0a0c79e06cc87e17530e9c1c56c6f297e17 (patch)
tree617d8e3b2d8be512373c3351a92630c28248ecee /mm/mempolicy.c
parent4146d2d673e8d6abf9b30a5b5dd8cd95f29632eb (diff)
downloadlinux-b79bc0a0c79e06cc87e17530e9c1c56c6f297e17.tar.gz
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>
Diffstat (limited to 'mm/mempolicy.c')
-rw-r--r--mm/mempolicy.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 2ae78e255e0..d344c36db63 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -496,9 +496,8 @@ static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
/*
* vm_normal_page() filters out zero pages, but there might
* still be PageReserved pages to skip, perhaps in a VDSO.
- * And we cannot move PageKsm pages sensibly or safely yet.
*/
- if (PageReserved(page) || PageKsm(page))
+ if (PageReserved(page))
continue;
nid = page_to_nid(page);
if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))