diff mbox series

[134/158] mm/migrate.c: handle freed page at the first place

Message ID 20191201015712.oGwSkH_BM%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/158] scripts/spelling.txt: add more spellings to spelling.txt | expand

Commit Message

Andrew Morton Dec. 1, 2019, 1:57 a.m. UTC
From: Yang Shi <yang.shi@linux.alibaba.com>
Subject: mm/migrate.c: handle freed page at the first place

When doing migration if the freed page is met, we just return without
migrating it since it is pointless to migrate a freed page.  But, the
current code allocates target page unconditionally before handling freed
page, if the page is freed, the newly allocated will be just freed.  It
doesn't make too much sense and is just a waste of time although migrating
freed page is rare.

So, handle freed page at the before that to avoid unnecessary page
allocation and free.

Link: http://lkml.kernel.org/r/1573755869-106954-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate.c |   14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)
diff mbox series

Patch

--- a/mm/migrate.c~mm-migrate-handle-freed-page-at-the-first-place
+++ a/mm/migrate.c
@@ -1168,15 +1168,11 @@  static ICE_noinline int unmap_and_move(n
 				   enum migrate_reason reason)
 {
 	int rc = MIGRATEPAGE_SUCCESS;
-	struct page *newpage;
+	struct page *newpage = NULL;
 
 	if (!thp_migration_supported() && PageTransHuge(page))
 		return -ENOMEM;
 
-	newpage = get_new_page(page, private);
-	if (!newpage)
-		return -ENOMEM;
-
 	if (page_count(page) == 1) {
 		/* page was freed from under us. So we are done. */
 		ClearPageActive(page);
@@ -1187,13 +1183,13 @@  static ICE_noinline int unmap_and_move(n
 				__ClearPageIsolated(page);
 			unlock_page(page);
 		}
-		if (put_new_page)
-			put_new_page(newpage, private);
-		else
-			put_page(newpage);
 		goto out;
 	}
 
+	newpage = get_new_page(page, private);
+	if (!newpage)
+		return -ENOMEM;
+
 	rc = __unmap_and_move(page, newpage, force, mode);
 	if (rc == MIGRATEPAGE_SUCCESS)
 		set_page_owner_migrate_reason(newpage, reason);