Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1408910

[PATCH] mm, page_alloc: prevent infinite loop in buffered_rmqueue()

Show all headers | View raw

From: Vlastimil Babka <vbabka@suse.cz>

In DEBUG_VM kernel, we can hit infinite loop for order == 0 in
buffered_rmqueue() when check_new_pcp() returns 1, because the bad page is
never removed from the pcp list. Fix this by removing the page before retrying.
Also we don't need to check if page is non-NULL, because we simply grab it from
the list which was just tested for being non-empty.

Fixes: http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-defer-debugging-checks-of-freed-pages-until-a-pcp-drain.patch
Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/page_alloc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f8f3bfc435ee..bb320cde4d6d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2609,11 +2609,12 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 				page = list_last_entry(list, struct page, lru);
 			else
 				page = list_first_entry(list, struct page, lru);
-		} while (page && check_new_pcp(page));
 
-		__dec_zone_state(zone, NR_ALLOC_BATCH);
-		list_del(&page->lru);
-		pcp->count--;
+			__dec_zone_state(zone, NR_ALLOC_BATCH);
+			list_del(&page->lru);
+			pcp->count--;
+
+		} while (check_new_pcp(page));
 	} else {
 		/*
 		 * We most definitely don't want callers attempting to

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH] mm, page_alloc: prevent infinite loop in buffered_rmqueue() Mel Gorman <mgorman@techsingularity.net> - 2016-05-30 11:10 +0200
  Re: [PATCH] mm, page_alloc: prevent infinite loop in  buffered_rmqueue() Vlastimil Babka <vbabka@suse.cz> - 2016-05-30 11:50 +0200
    Re: [PATCH] mm, page_alloc: prevent infinite loop in  buffered_rmqueue() Mel Gorman <mgorman@techsingularity.net> - 2016-05-30 13:00 +0200

csiph-web