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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2010-09-09 23:38:01 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2010-09-10 01:57:24 (GMT)
commit0dcc48c15f63ee86c2fcd33968b08d651f0360a5 (patch)
treed182a43200204be2fea04bcb80b824c6f4941267 /mm/memory_hotplug.c
parentbc6930457460788e14b2c0808ed4632a1592bd61 (diff)
memory hotplug: fix next block calculation in is_removable
next_active_pageblock() is for finding next _used_ freeblock. It skips several blocks when it finds there are a chunk of free pages lager than pageblock. But it has 2 bugs. 1. We have no lock. page_order(page) - pageblock_order can be minus. 2. pageblocks_stride += is wrong. it should skip page_order(p) of pages. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory_hotplug.c')
-rw-r--r--mm/memory_hotplug.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a4cfcdc..dd186c1 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -584,19 +584,19 @@ static inline int pageblock_free(struct page *page)
/* Return the start of the next active pageblock after a given page */
static struct page *next_active_pageblock(struct page *page)
{
- int pageblocks_stride;
-
/* Ensure the starting page is pageblock-aligned */
BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
- /* Move forward by at least 1 * pageblock_nr_pages */
- pageblocks_stride = 1;
-
/* If the entire pageblock is free, move to the end of free page */
- if (pageblock_free(page))
- pageblocks_stride += page_order(page) - pageblock_order;
+ if (pageblock_free(page)) {
+ int order;
+ /* be careful. we don't have locks, page_order can be changed.*/
+ order = page_order(page);
+ if ((order < MAX_ORDER) && (order >= pageblock_order))
+ return page + (1 << order);
+ }
- return page + (pageblocks_stride * pageblock_nr_pages);
+ return page + pageblock_nr_pages;
}
/* Checks if this range of memory is likely to be hot-removable. */

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