memory hotplug: fix next block calculation in is_removable (0dcc48c1) · Commits · 戴 / test

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>

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. */

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