Messages in this thread | | | From | "Hillf Danton" <> | Subject | Re: [PATCH 1/2] mm, page_alloc: Keep pcp count and list contents in sync if struct page is corrupted | Date | Fri, 02 Dec 2016 17:30:07 +0800 |
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On Friday, December 02, 2016 2:19 PM Vlastimil Babka wrote: > 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@suse.de> > >> cc: stable@vger.kernel.org [4.7+] > > Acked-by: Vlastimil Babka <vbabka@suse.cz> > > >> --- > >> 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. > Yes, we can allocate free page next time.
thanks Hillf
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