[tip:sched/core] mm: numa: Copy cpupid on page migration

[tip-bot for Rik van Riel]

Commit-ID:  7851a45cd3f6198bf542c30e27b330e8eeb3736c
Gitweb:     http://git.kernel.org/tip/7851a45cd3f6198bf542c30e27b330e8eeb3736c
Author:     Rik van Riel <riel@xxxxxxxxxx>
AuthorDate: Mon, 7 Oct 2013 11:29:23 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 9 Oct 2013 14:47:51 +0200

mm: numa: Copy cpupid on page migration

After page migration, the new page has the nidpid unset. This makes
every fault on a recently migrated page look like a first numa fault,
leading to another page migration.

Copying over the nidpid at page migration time should prevent erroneous
migrations of recently migrated pages.

Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1381141781-10992-46-git-send-email-mgorman@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 mm/migrate.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/mm/migrate.c b/mm/migrate.c
index ff53774..44c1fa9 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -443,6 +443,8 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
  */
 void migrate_page_copy(struct page *newpage, struct page *page)
 {
+	int cpupid;
+
 	if (PageHuge(page) || PageTransHuge(page))
 		copy_huge_page(newpage, page);
 	else
@@ -479,6 +481,13 @@ void migrate_page_copy(struct page *newpage, struct page *page)
 			__set_page_dirty_nobuffers(newpage);
  	}
 
+	/*
+	 * Copy NUMA information to the new page, to prevent over-eager
+	 * future migrations of this same page.
+	 */
+	cpupid = page_cpupid_xchg_last(page, -1);
+	page_cpupid_xchg_last(newpage, cpupid);
+
 	mlock_migrate_page(newpage, page);
 	ksm_migrate_page(newpage, page);
 	/*
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/