Commit 8cc3b392 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

badpage: keep any bad page out of circulation 



Until now the bad_page() checkers have special-cased PageReserved, keeping
those pages out of circulation thereafter.  Now extend the special case to
all: we want to keep ANY page with bad state out of circulation - the
"free" page may well be in use by something.

Leave the bad state of those pages untouched, for examination by
debuggers; except for PageBuddy - leaving that set would risk bringing the
page back.

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 79f4b7bf

mm/page_alloc.c

+24 −28
Original line number Diff line number Diff line
@@ -231,9 +231,9 @@ static void bad_page(struct page *page) 
	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"

		KERN_EMERG "Backtrace:\n");

	dump_stack();

	set_page_count(page, 0);

	reset_page_mapcount(page);

	page->mapping = NULL;



	/* Leave bad fields for debug, except PageBuddy could make trouble */

	__ClearPageBuddy(page);

	add_taint(TAINT_BAD_PAGE);

}
@@ -290,25 +290,31 @@ void prep_compound_gigantic_page(struct page *page, unsigned long order) 
}

#endif



static void destroy_compound_page(struct page *page, unsigned long order)

static int destroy_compound_page(struct page *page, unsigned long order)

{

	int i;

	int nr_pages = 1 << order;

	int bad = 0;



	if (unlikely(compound_order(page) != order))

	if (unlikely(compound_order(page) != order) ||

	    unlikely(!PageHead(page))) {

		bad_page(page);

		bad++;

	}



	if (unlikely(!PageHead(page)))

			bad_page(page);

	__ClearPageHead(page);



	for (i = 1; i < nr_pages; i++) {

		struct page *p = page + i;



		if (unlikely(!PageTail(p) |

				(p->first_page != page)))

		if (unlikely(!PageTail(p) | (p->first_page != page))) {

			bad_page(page);

			bad++;

		}

		__ClearPageTail(p);

	}



	return bad;

}



static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
@@ -428,7 +434,8 @@ static inline void __free_one_page(struct page *page, 
	int migratetype = get_pageblock_migratetype(page);



	if (unlikely(PageCompound(page)))

		destroy_compound_page(page, order);

		if (unlikely(destroy_compound_page(page, order)))

			return;



	page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
@@ -465,15 +472,10 @@ static inline int free_pages_check(struct page *page) 
	if (unlikely(page_mapcount(page) |

		(page->mapping != NULL)  |

		(page_count(page) != 0)  |

		(page->flags & PAGE_FLAGS_CHECK_AT_FREE)))

		(page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {

		bad_page(page);

	/*

	 * For now, we report if PG_reserved was found set, but do not

	 * clear it, and do not free the page.  But we shall soon need

	 * to do more, for when the ZERO_PAGE count wraps negative.

	 */

	if (PageReserved(page))

		return 1;

	}

	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)

		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;

	return 0;
@@ -521,11 +523,11 @@ static void __free_pages_ok(struct page *page, unsigned int order) 
{

	unsigned long flags;

	int i;

	int reserved = 0;

	int bad = 0;



	for (i = 0 ; i < (1 << order) ; ++i)

		reserved += free_pages_check(page + i);

	if (reserved)

		bad += free_pages_check(page + i);

	if (bad)

		return;



	if (!PageHighMem(page)) {
@@ -610,17 +612,11 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags) 
	if (unlikely(page_mapcount(page) |

		(page->mapping != NULL)  |

		(page_count(page) != 0)  |

		(page->flags & PAGE_FLAGS_CHECK_AT_PREP)))

		(page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {

		bad_page(page);



	/*

	 * For now, we report if PG_reserved was found set, but do not

	 * clear it, and do not allocate the page: as a safety net.

	 */

	if (PageReserved(page))

		return 1;

	}



	page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;

	set_page_private(page, 0);

	set_page_refcounted(page);

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