Commit 97d0da22 authored by Wen Congyang's avatar Wen Congyang Committed by Linus Torvalds
Browse files

memory-hotplug: fix NR_FREE_PAGES mismatch

NR_FREE_PAGES will be wrong after offlining pages.  We add/dec
NR_FREE_PAGES like this now:

1. move 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

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
Signed-off-by: default avatarWen Congyang <>
Cc: David Rientjes <>
Cc: Jiang Liu <>
Cc: Len Brown <>
Cc: Benjamin Herrenschmidt <>
Cc: Paul Mackerras <>
Cc: Christoph Lameter <>
Cc: Minchan Kim <>
Cc: KOSAKI Motohiro <>
Cc: Yasuaki Ishimatsu <>
Cc: Dave Hansen <>
Cc: Mel Gorman <>
Cc: Jianguo Wu <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 7c72eb32
......@@ -667,11 +667,13 @@ static void free_pcppages_bulk(struct zone *zone, int count,
__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(get_pageblock_migratetype(page) != 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);
......@@ -6047,8 +6049,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
__mod_zone_page_state(zone, NR_FREE_PAGES,
- (1UL << order));
for (i = 0; i < (1 << order); i++)
pfn += (1 << order);
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