lkml.org 
[lkml]   [2015]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] mm: hwpoison: drop lru_add_drain_all() in __soft_offline_page()
Date
A race condition starts to be visible in recent mmotm, where a PG_hwpoison
flag is set on a migration source page *before* it's back in buddy page pool.
This is problematic because no page flag is supposed to be set when freeing
(see __free_one_page().) So the user-visible effect of this race is that it
could trigger the BUG_ON() when soft-offlining is called.

The root cause is that we call lru_add_drain_all() to make sure that the
page is in buddy, but that doesn't work because this function just schedules
a work item and doesn't wait its completion. drain_all_pages() does draining
directly, so simply dropping lru_add_drain_all() solves this problem.

Fixes: commit f15bdfa802bf ("mm/memory-failure.c: fix memory leak in successful soft offlining")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org> [3.11+]
---
mm/memory-failure.c | 2 --
1 file changed, 2 deletions(-)

diff --git mmotm-2015-02-03-16-38.orig/mm/memory-failure.c mmotm-2015-02-03-16-38/mm/memory-failure.c
index b2a68bde8058..fa44054c205f 100644
--- mmotm-2015-02-03-16-38.orig/mm/memory-failure.c
+++ mmotm-2015-02-03-16-38/mm/memory-failure.c
@@ -1647,8 +1647,6 @@ static int __soft_offline_page(struct page *page, int flags)
* setting PG_hwpoison.
*/
if (!is_free_buddy_page(page))
- lru_add_drain_all();
- if (!is_free_buddy_page(page))
drain_all_pages(page_zone(page));
SetPageHWPoison(page);
if (!is_free_buddy_page(page))
--
1.9.3

\
 
 \ /
  Last update: 2015-02-10 06:01    [W:0.033 / U:27.684 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site