[PATCH 4/6] mm/hwpoison: don't set migration type twice to avoid hold heavy contend zone->lock

[Wanpeng Li <liwanp@linux.vnet.ibm.com>]

Set pageblock migration type will hold zone->lock which is heavy contended 
in system to avoid race. However, soft offline page will set pageblock 
migration type twice during get page if the page is in used, not hugetlbfs 
page and not on lru list. There is unnecessary to set the pageblock migration
type and hold heavy contended zone->lock again if the first round get page 
have already set the pageblock to right migration type.

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
---
 mm/memory-failure.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 6bfd51e..3bfb45f 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1413,7 +1413,8 @@ static int __get_any_page(struct page *p, unsigned long pfn, int flags)
 	 * was free. This flag should be kept set until the source page
 	 * is freed and PG_hwpoison on it is set.
 	 */
-	set_migratetype_isolate(p, true);
+	if (get_pageblock_migratetype(p) == MIGRATE_ISOLATE)
+		set_migratetype_isolate(p, true);
 	/*
 	 * When the target page is a free hugepage, just remove it
 	 * from free hugepage list.
-- 
1.8.1.2