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Commit 0dcc48c1 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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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: default avatarKAMEZAWA 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bc693045

mm/memory_hotplug.c

+8 −8
Original line number Diff line number Diff line
@@ -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. */