[PATCH 16/18] mm: numa: Do not automatically migrate KSM pages

[Mel Gorman]

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@xxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
---
 mm/mprotect.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 9b1be30..c258137 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);
 						updated = true;
-- 
1.8.4

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