[PATCH 23/36] autonuma: retain page last_nid information in khugepaged

[Andrea Arcangeli <aarcange@xxxxxxxxxx>]

When pages are collapsed try to keep the last_nid information from one
of the original pages.

Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
 mm/huge_memory.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a65590f..0d2a12f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1829,6 +1829,9 @@ static bool __collapse_huge_page_copy(pte_t *pte, struct page *page,
 {
 	pte_t *_pte;
 	bool mknuma = false;
+#ifdef CONFIG_AUTONUMA
+	int autonuma_last_nid = -1;
+#endif
 	for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
 		pte_t pteval = *_pte;
 		struct page *src_page;
@@ -1838,6 +1841,17 @@ static bool __collapse_huge_page_copy(pte_t *pte, struct page *page,
 			add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
 		} else {
 			src_page = pte_page(pteval);
+#ifdef CONFIG_AUTONUMA
+			/* pick the first one, better than nothing */
+			if (autonuma_last_nid < 0) {
+				autonuma_last_nid =
+					ACCESS_ONCE(src_page->
+						    autonuma_last_nid);
+				if (autonuma_last_nid >= 0)
+					ACCESS_ONCE(page->autonuma_last_nid) =
+						autonuma_last_nid;
+			}
+#endif
 			copy_user_highpage(page, src_page, address, vma);
 			VM_BUG_ON(page_mapcount(src_page) != 1);
 			VM_BUG_ON(page_count(src_page) != 0);
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