linux-kernel - [PATCH v1] mm: migrate: hugetlb: putback destination hugepage to active list

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Date:	Wed, 16 Sep 2015 00:21:04 +0000
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Michal Hocko <mhocko@...e.cz>, Andi Kleen <andi@...stfloor.org>,
	"Hugh Dickins" <hughd@...gle.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Naoya Horiguchi" <n-horiguchi@...jp.nec.com>
Subject: [PATCH v1] mm: migrate: hugetlb: putback destination hugepage to
 active list

Since commit bcc54222309c ("mm: hugetlb: introduce page_huge_active")
each hugetlb page maintains its active flag to avoid a race condition between
multiple calls of isolate_huge_page(), but current kernel doesn't set the flag
on a hugepage allocated by migration because the proper putback routine isn't
called. This means that users could still encounter the race referred to by
bcc54222309c in this special case, so this patch fixes it.

Fixes: bcc54222309c ("mm: hugetlb: introduce page_huge_active")
Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: <stable@...r.kernel.org>  #4.1
---
 mm/migrate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git v4.3-rc1/mm/migrate.c v4.3-rc1_patched/mm/migrate.c
index c3cb566af3e2..7452a00bbb50 100644
--- v4.3-rc1/mm/migrate.c
+++ v4.3-rc1_patched/mm/migrate.c
@@ -1075,7 +1075,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	if (rc != MIGRATEPAGE_SUCCESS && put_new_page)
 		put_new_page(new_hpage, private);
 	else
-		put_page(new_hpage);
+		putback_active_hugepage(new_hpage);
 
 	if (result) {
 		if (rc)
-- 
2.4.3
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