Commit 6fb332fa authored Sep 21, 2009 by Shaohua Li Committed by Linus Torvalds Sep 22, 2009

memory hotplug: exclude isolated page from pco page alloc



Pages marked as isolated should not be allocated again.  If such pages
reside in pcp list, they can be allocated too, so there is a ping-pong
memory offline frees some pages to pcp list and the pages get allocated
and then memory offline frees them again, this loop will happen again and
again.

This should have no impact in normal code path, because in normal code
path, pages in pcp list aren't isolated, and below loop will break in the
first entry.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Yakui Zhao <yakui.zhao@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 112067f0

mm/page_alloc.c

+11 −1

Original line number	Diff line number	Diff line
		@@ -1143,10 +1143,20 @@ again:

		/* Allocate more to the pcp list if necessary */
		if (unlikely(&page->lru == &pcp->list)) {
		int get_one_page = 0;

		pcp->count += rmqueue_bulk(zone, 0,
		pcp->batch, &pcp->list,
		migratetype, cold);
		page = list_entry(pcp->list.next, struct page, lru);
		list_for_each_entry(page, &pcp->list, lru) {
		if (get_pageblock_migratetype(page) !=
		MIGRATE_ISOLATE) {
		get_one_page = 1;
		break;
		}
		}
		if (!get_one_page)
		goto failed;
		}

		list_del(&page->lru);

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