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authorMinchan Kim <minchan@kernel.org>2012-10-08 16:32:14 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:22:46 +0900
commit41d575ad4a511b71a4a41c8313004212f5c229b1 (patch)
tree04d9fe90086a7c4be7b680c3adc592086baccfe5
parent95e3441248053fc06bbb1dbbd34409a84211619e (diff)
downloadlinux-41d575ad4a511b71a4a41c8313004212f5c229b1.tar.gz
memory-hotplug: bug fix race between isolation and allocation
Like below, memory-hotplug makes race between page-isolation and page-allocation so it can hit BUG_ON in __offline_isolated_pages. CPU A CPU B start_isolate_page_range set_migratetype_isolate spin_lock_irqsave(zone->lock) free_hot_cold_page(Page A) /* without zone->lock */ migratetype = get_pageblock_migratetype(Page A); /* * Page could be moved into MIGRATE_MOVABLE * of per_cpu_pages */ list_add_tail(&page->lru, &pcp->lists[migratetype]); set_pageblock_isolate move_freepages_block drain_all_pages /* Page A could be in MIGRATE_MOVABLE of free_list. */ check_pages_isolated __test_page_isolated_in_pageblock /* * We can't catch freed page which * is free_list[MIGRATE_MOVABLE] */ if (PageBuddy(page A)) pfn += 1 << page_order(page A); /* So, Page A could be allocated */ __offline_isolated_pages /* * BUG_ON hit or offline page * which is used by someone */ BUG_ON(!PageBuddy(page A)); This patch checks page's migratetype in freelist in __test_page_isolated_in_pageblock. So now __test_page_isolated_in_pageblock can check the page caused by above race and can fail of memory offlining. Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_isolation.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 9c03dca8c2a..6744235d2d0 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -200,8 +200,11 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
continue;
}
page = pfn_to_page(pfn);
- if (PageBuddy(page))
+ if (PageBuddy(page)) {
+ if (get_freepage_migratetype(page) != MIGRATE_ISOLATE)
+ break;
pfn += 1 << page_order(page);
+ }
else if (page_count(page) == 0 &&
get_freepage_migratetype(page) == MIGRATE_ISOLATE)
pfn += 1;