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authorMinchan Kim <minchan@kernel.org>2012-10-08 16:32:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:22:46 +0900
commit435b405c06119d93333738172b8060b0ed12af41 (patch)
treea87f9a493f5c677ab23eeab1eab2e45caeb79bc3 /mm/page_isolation.c
parent41d575ad4a511b71a4a41c8313004212f5c229b1 (diff)
downloadlinux-435b405c06119d93333738172b8060b0ed12af41.tar.gz
memory-hotplug: fix pages missed by race rather than failing
If race between allocation and isolation in memory-hotplug offline happens, some pages could be in MIGRATE_MOVABLE of free_list although the pageblock's migratetype of the page is MIGRATE_ISOLATE. The race could be detected by get_freepage_migratetype in __test_page_isolated_in_pageblock. If it is detected, now EBUSY gets bubbled all the way up and the hotplug operations fails. But better idea is instead of returning and failing memory-hotremove, move the free page to the correct list at the time it is detected. It could enhance memory-hotremove operation success ratio although the race is really rare. Suggested by Mel Gorman. [akpm@linux-foundation.org: small cleanup] Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: 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>
Diffstat (limited to 'mm/page_isolation.c')
-rw-r--r--mm/page_isolation.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 6744235d2d0..5f34a9053ce 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -201,8 +201,20 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
}
page = pfn_to_page(pfn);
if (PageBuddy(page)) {
- if (get_freepage_migratetype(page) != MIGRATE_ISOLATE)
- break;
+ /*
+ * If race between isolatation and allocation happens,
+ * some free pages could be in MIGRATE_MOVABLE list
+ * although pageblock's migratation type of the page
+ * is MIGRATE_ISOLATE. Catch it and move the page into
+ * MIGRATE_ISOLATE list.
+ */
+ if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) {
+ struct page *end_page;
+
+ end_page = page + (1 << page_order(page)) - 1;
+ move_freepages(page_zone(page), page, end_page,
+ MIGRATE_ISOLATE);
+ }
pfn += 1 << page_order(page);
}
else if (page_count(page) == 0 &&