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Commit 8d22ba1b authored by Wu Fengguang's avatar Wu Fengguang Committed by Andi Kleen
Browse files

HWPOISON: detect free buddy pages explicitly 



Most free pages in the buddy system have no PG_buddy set.
Introduce is_free_buddy_page() for detecting them reliably.

CC: Nick Piggin <npiggin@suse.de>
CC: Mel Gorman <mel@linux.vnet.ibm.com>
Signed-off-by: default avatarWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
parent 95d01fc6

mm/internal.h

+3 −0
Original line number Diff line number Diff line
@@ -50,6 +50,9 @@ extern void putback_lru_page(struct page *page); 
 */

extern void __free_pages_bootmem(struct page *page, unsigned int order);

extern void prep_compound_page(struct page *page, unsigned long order);

#ifdef CONFIG_MEMORY_FAILURE

extern bool is_free_buddy_page(struct page *page);

#endif





/*

mm/memory-failure.c

+7 −2
Original line number Diff line number Diff line
@@ -807,8 +807,13 @@ int __memory_failure(unsigned long pfn, int trapno, int flags) 
	 */

	if (!(flags & MF_COUNT_INCREASED) &&

		!get_page_unless_zero(compound_head(p))) {

		action_result(pfn, "free or high order kernel", IGNORED);

		return PageBuddy(compound_head(p)) ? 0 : -EBUSY;

		if (is_free_buddy_page(p)) {

			action_result(pfn, "free buddy", DELAYED);

			return 0;

		} else {

			action_result(pfn, "high order kernel", IGNORED);

			return -EBUSY;

		}

	}



	/*

mm/page_alloc.c

+21 −0
Original line number Diff line number Diff line
@@ -5081,3 +5081,24 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) 
	spin_unlock_irqrestore(&zone->lock, flags);

}

#endif



#ifdef CONFIG_MEMORY_FAILURE

bool is_free_buddy_page(struct page *page)

{

	struct zone *zone = page_zone(page);

	unsigned long pfn = page_to_pfn(page);

	unsigned long flags;

	int order;



	spin_lock_irqsave(&zone->lock, flags);

	for (order = 0; order < MAX_ORDER; order++) {

		struct page *page_head = page - (pfn & ((1 << order) - 1));



		if (PageBuddy(page_head) && page_order(page_head) >= order)

			break;

	}

	spin_unlock_irqrestore(&zone->lock, flags);



	return order < MAX_ORDER;

}

#endif