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authorMel Gorman <mgorman@techsingularity.net>2016-12-12 16:44:41 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-01-06 10:40:15 +0100
commit44919a2ac4c6eca9f6e076e4485e06f251101a9a (patch)
treeba823a12ba78eefe3d824220be0d7e15a4f2129d /mm/page_alloc.c
parent04597beae7c23ccefd4502c0b9296d68292b807f (diff)
mm, page_alloc: keep pcp count and list contents in sync if struct page is corrupted
commit a6de734bc002fe2027ccc074fbbd87d72957b7a4 upstream. Vlastimil Babka pointed out that commit 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") will allow the per-cpu list counter to be out of sync with the per-cpu list contents if a struct page is corrupted. The consequence is an infinite loop if the per-cpu lists get fully drained by free_pcppages_bulk because all the lists are empty but the count is positive. The infinite loop occurs here do { batch_free++; if (++migratetype == MIGRATE_PCPTYPES) migratetype = 0; list = &pcp->lists[migratetype]; } while (list_empty(list)); What the user sees is a bad page warning followed by a soft lockup with interrupts disabled in free_pcppages_bulk(). This patch keeps the accounting in sync. Fixes: 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") Link: http://lkml.kernel.org/r/20161202112951.23346-2-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6de9440e3ae2..34ada718ef47 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2192,7 +2192,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
unsigned long count, struct list_head *list,
int migratetype, bool cold)
{
- int i;
+ int i, alloced = 0;
spin_lock(&zone->lock);
for (i = 0; i < count; ++i) {
@@ -2217,13 +2217,21 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
else
list_add_tail(&page->lru, list);
list = &page->lru;
+ alloced++;
if (is_migrate_cma(get_pcppage_migratetype(page)))
__mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
-(1 << order));
}
+
+ /*
+ * i pages were removed from the buddy list even if some leak due
+ * to check_pcp_refill failing so adjust NR_FREE_PAGES based
+ * on i. Do not confuse with 'alloced' which is the number of
+ * pages added to the pcp list.
+ */
__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
spin_unlock(&zone->lock);
- return i;
+ return alloced;
}
#ifdef CONFIG_NUMA