Commit 689bcebf authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

[PATCH] unpaged: PG_reserved bad_page 



It used to be the case that PG_reserved pages were silently never freed, but
in 2.6.15-rc1 they may be freed with a "Bad page state" message.  We should
work through such cases as they appear, fixing the code; but for now it's
safer to issue the message without freeing the page, leaving PG_reserved set.

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f57e88a8

mm/page_alloc.c

+34 −12
Original line number Diff line number Diff line
@@ -140,8 +140,7 @@ static void bad_page(const char *function, struct page *page) 
			1 << PG_reclaim |

			1 << PG_slab    |

			1 << PG_swapcache |

			1 << PG_writeback |

			1 << PG_reserved );

			1 << PG_writeback );

	set_page_count(page, 0);

	reset_page_mapcount(page);

	page->mapping = NULL;
@@ -335,7 +334,7 @@ static inline void __free_pages_bulk (struct page *page, 
	zone->free_area[order].nr_free++;

}



static inline void free_pages_check(const char *function, struct page *page)

static inline int free_pages_check(const char *function, struct page *page)

{

	if (	page_mapcount(page) ||

		page->mapping != NULL ||
@@ -353,6 +352,12 @@ static inline void free_pages_check(const char *function, struct page *page) 
		bad_page(function, page);

	if (PageDirty(page))

		__ClearPageDirty(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.

	 */

	return PageReserved(page);

}



/*
@@ -392,11 +397,10 @@ void __free_pages_ok(struct page *page, unsigned int order) 
{

	LIST_HEAD(list);

	int i;

	int reserved = 0;



	arch_free_page(page, order);



	mod_page_state(pgfree, 1 << order);



#ifndef CONFIG_MMU

	if (order > 0)

		for (i = 1 ; i < (1 << order) ; ++i)
@@ -404,8 +408,12 @@ void __free_pages_ok(struct page *page, unsigned int order) 
#endif



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

		free_pages_check(__FUNCTION__, page + i);

		reserved += free_pages_check(__FUNCTION__, page + i);

	if (reserved)

		return;



	list_add(&page->lru, &list);

	mod_page_state(pgfree, 1 << order);

	kernel_map_pages(page, 1<<order, 0);

	free_pages_bulk(page_zone(page), 1, &list, order);

}
@@ -463,7 +471,7 @@ void set_page_refs(struct page *page, int order) 
/*

 * This page is about to be returned from the page allocator

 */

static void prep_new_page(struct page *page, int order)

static int prep_new_page(struct page *page, int order)

{

	if (	page_mapcount(page) ||

		page->mapping != NULL ||
@@ -481,12 +489,20 @@ static void prep_new_page(struct page *page, int order) 
			1 << PG_reserved )))

		bad_page(__FUNCTION__, 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 &= ~(1 << PG_uptodate | 1 << PG_error |

			1 << PG_referenced | 1 << PG_arch_1 |

			1 << PG_checked | 1 << PG_mappedtodisk);

	set_page_private(page, 0);

	set_page_refs(page, order);

	kernel_map_pages(page, 1 << order, 1);

	return 0;

}



/*
@@ -669,11 +685,14 @@ static void fastcall free_hot_cold_page(struct page *page, int cold) 


	arch_free_page(page, 0);



	kernel_map_pages(page, 1, 0);

	inc_page_state(pgfree);

	if (PageAnon(page))

		page->mapping = NULL;

	free_pages_check(__FUNCTION__, page);

	if (free_pages_check(__FUNCTION__, page))

		return;



	inc_page_state(pgfree);

	kernel_map_pages(page, 1, 0);



	pcp = &zone_pcp(zone, get_cpu())->pcp[cold];

	local_irq_save(flags);

	list_add(&page->lru, &pcp->list);
@@ -712,12 +731,14 @@ static struct page * 
buffered_rmqueue(struct zone *zone, int order, gfp_t gfp_flags)

{

	unsigned long flags;

	struct page *page = NULL;

	struct page *page;

	int cold = !!(gfp_flags & __GFP_COLD);



again:

	if (order == 0) {

		struct per_cpu_pages *pcp;



		page = NULL;

		pcp = &zone_pcp(zone, get_cpu())->pcp[cold];

		local_irq_save(flags);

		if (pcp->count <= pcp->low)
@@ -739,7 +760,8 @@ buffered_rmqueue(struct zone *zone, int order, gfp_t gfp_flags) 
	if (page != NULL) {

		BUG_ON(bad_range(zone, page));

		mod_page_state_zone(zone, pgalloc, 1 << order);

		prep_new_page(page, order);

		if (prep_new_page(page, order))

			goto again;



		if (gfp_flags & __GFP_ZERO)

			prep_zero_page(page, order, gfp_flags);

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