On 12/02/2016 04:47 AM, Hillf Danton wrote:
On Friday, December 02, 2016 8:23 AM Mel Gorman wrote: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. This patch keeps the accounting in sync. Fixes: 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") Signed-off-by: Mel Gorman <mgorman@xxxxxxx> cc: stable@xxxxxxxxxxxxxxx [4.7+]
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
--- mm/page_alloc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6de9440e3ae2..777ed59570df 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 +2217,14 @@ 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)); } __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));Now i is a pure index, yes?
No, even if a page fails the check_pcp_refill() check and is not "allocated", it is also no longer a free page, so it's correct to subtract it from NR_FREE_PAGES.
spin_unlock(&zone->lock); - return i; + return alloced; } #ifdef CONFIG_NUMA -- 2.10.2
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