From: sunqiuyang <sunqiuyang@huawei.com>
To: <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>
Cc: <sunqiuyang@huawei.com>
Subject: [PATCH 1/1] mm/migrate: fix list corruption in migration of non-LRU movable pages
Date: Tue, 3 Sep 2019 16:27:46 +0800 [thread overview]
Message-ID: <20190903082746.20736-1-sunqiuyang@huawei.com> (raw)
From: Qiuyang Sun <sunqiuyang@huawei.com>
Currently, after a page is migrated, it
1) has its PG_isolated flag cleared in move_to_new_page(), and
2) is deleted from its LRU list (cc->migratepages) in unmap_and_move().
However, between steps 1) and 2), the page could be isolated by another
thread in isolate_movable_page(), and added to another LRU list, leading
to list_del corruption later.
This patch fixes the bug by moving list_del into the critical section
protected by lock_page(), so that a page will not be isolated again before
it has been deleted from its LRU list.
Signed-off-by: Qiuyang Sun <sunqiuyang@huawei.com>
---
mm/migrate.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index a42858d..c58a606 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1124,6 +1124,8 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
/* Drop an anon_vma reference if we took one */
if (anon_vma)
put_anon_vma(anon_vma);
+ if (rc != -EAGAIN)
+ list_del(&page->lru);
unlock_page(page);
out:
/*
@@ -1190,6 +1192,7 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
put_new_page(newpage, private);
else
put_page(newpage);
+ list_del(&page->lru);
goto out;
}
@@ -1200,14 +1203,6 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
out:
if (rc != -EAGAIN) {
/*
- * A page that has been migrated has all references
- * removed and will be freed. A page that has not been
- * migrated will have kepts its references and be
- * restored.
- */
- list_del(&page->lru);
-
- /*
* Compaction can migrate also non-LRU pages which are
* not accounted to NR_ISOLATED_*. They can be recognized
* as __PageMovable
--
1.8.3.1
next reply other threads:[~2019-09-03 8:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-03 8:27 sunqiuyang [this message]
2019-09-03 13:17 ` [PATCH 1/1] mm/migrate: fix list corruption in migration of non-LRU movable pages Michal Hocko
2019-09-04 2:18 ` sunqiuyang
2019-09-04 6:38 ` Michal Hocko
2019-09-04 7:27 ` sunqiuyang
2019-09-04 8:14 ` Michal Hocko
2019-09-04 12:19 ` sunqiuyang
2019-09-04 12:52 ` Michal Hocko
2019-09-05 1:44 ` sunqiuyang
2019-09-09 8:40 ` Michal Hocko
2019-09-12 17:21 ` Minchan Kim
2019-09-10 19:23 ` Minchan Kim
2019-09-10 19:31 ` Michal Hocko
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