Messages in this thread Patch in this message | | | From | wency@cn ... | Subject | [PATCH v3 8/9] memory-hotplug: fix NR_FREE_PAGES mismatch | Date | Fri, 19 Oct 2012 14:46:41 +0800 |
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From: Wen Congyang <wency@cn.fujitsu.com>
NR_FREE_PAGES will be wrong after offlining pages. We add/dec NR_FREE_PAGES like this now: 1. mova all pages in buddy system to MIGRATE_ISOLATE, and dec NR_FREE_PAGES 2. don't add NR_FREE_PAGES when it is freed and the migratetype is MIGRATE_ISOLATE 3. dec NR_FREE_PAGES when offlining isolated pages. 4. add NR_FREE_PAGES when undoing isolate pages.
When we come to step 3, all pages are in MIGRATE_ISOLATE list, and NR_FREE_PAGES are right. When we come to step4, all pages are not in buddy system, so we don't change NR_FREE_PAGES in this step, but we change NR_FREE_PAGES in step3. So NR_FREE_PAGES is wrong after offlining pages. So there is no need to change NR_FREE_PAGES in step3.
This patch also fixs a problem in step2: if the migratetype is MIGRATE_ISOLATE, we should not add NR_FRR_PAGES when we remove pages from pcppages.
CC: David Rientjes <rientjes@google.com> CC: Jiang Liu <liuj97@gmail.com> CC: Len Brown <len.brown@intel.com> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: Paul Mackerras <paulus@samba.org> CC: Christoph Lameter <cl@linux.com> Cc: Minchan Kim <minchan.kim@gmail.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> --- mm/page_alloc.c | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index e33d0fb..9aa9490 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -667,11 +667,13 @@ static void free_pcppages_bulk(struct zone *zone, int count, /* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */ __free_one_page(page, zone, 0, mt); trace_mm_page_pcpu_drain(page, 0, mt); - if (is_migrate_cma(mt)) - __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1); + if (likely(mt != MIGRATE_ISOLATE)) { + __mod_zone_page_state(zone, NR_FREE_PAGES, 1); + if (is_migrate_cma(mt)) + __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1); + } } while (--to_free && --batch_free && !list_empty(list)); } - __mod_zone_page_state(zone, NR_FREE_PAGES, count); spin_unlock(&zone->lock); } @@ -6006,8 +6008,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) list_del(&page->lru); rmv_page_order(page); zone->free_area[order].nr_free--; - __mod_zone_page_state(zone, NR_FREE_PAGES, - - (1UL << order)); for (i = 0; i < (1 << order); i++) SetPageReserved((page+i)); pfn += (1 << order); -- 1.7.1
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