[Trusty][SRU][PATCH] mm: numa: do not automatically migrate KSM pages

[Chris J Arges]

From: Mel Gorman <mgorman at suse.de>

BugLink: http://bugs.launchpad.net/bugs/1346917

KSM pages can be shared between tasks that are not necessarily related
to each other from a NUMA perspective.  This patch causes those pages to
be ignored by automatic NUMA balancing so they do not migrate and do not
cause unrelated tasks to be grouped together.

Signed-off-by: Mel Gorman <mgorman at suse.de>
Reviewed-by: Rik van Riel <riel at redhat.com>
Cc: Alex Thorlton <athorlton at sgi.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
(cherry picked from commit 64a9a34e22896dad430e21a28ad8cb00a756fefc)
Signed-off-by: Chris J Arges <chris.j.arges at canonical.com>
---
 mm/mprotect.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index bb53a65..7332c17 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -23,6 +23,7 @@
 #include <linux/mmu_notifier.h>
 #include <linux/migrate.h>
 #include <linux/perf_event.h>
+#include <linux/ksm.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/cacheflush.h>
@@ -63,7 +64,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
 
 				ptent = *pte;
 				page = vm_normal_page(vma, addr, oldpte);
-				if (page) {
+				if (page && !PageKsm(page)) {
 					if (!pte_numa(oldpte)) {
 						ptent = pte_mknuma(ptent);
 						set_pte_at(mm, addr, pte, ptent);
-- 
1.9.1