[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: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -140,8 +140,7 @@ static void bad_page(const char *function, struct page *page)
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1 << PG_reclaim |
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1 << PG_slab |
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1 << PG_swapcache |
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1 << PG_writeback |
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1 << PG_reserved );
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1 << PG_writeback );
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set_page_count(page, 0);
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reset_page_mapcount(page);
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page->mapping = NULL;
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@ -335,7 +334,7 @@ static inline void __free_pages_bulk (struct page *page,
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zone->free_area[order].nr_free++;
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}
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static inline void free_pages_check(const char *function, struct page *page)
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static inline int free_pages_check(const char *function, struct page *page)
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{
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if ( page_mapcount(page) ||
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page->mapping != NULL ||
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@ -353,6 +352,12 @@ static inline void free_pages_check(const char *function, struct page *page)
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bad_page(function, page);
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if (PageDirty(page))
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__ClearPageDirty(page);
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/*
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* For now, we report if PG_reserved was found set, but do not
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* clear it, and do not free the page. But we shall soon need
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* to do more, for when the ZERO_PAGE count wraps negative.
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*/
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return PageReserved(page);
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}
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/*
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@ -392,11 +397,10 @@ void __free_pages_ok(struct page *page, unsigned int order)
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{
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LIST_HEAD(list);
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int i;
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int reserved = 0;
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arch_free_page(page, order);
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mod_page_state(pgfree, 1 << order);
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#ifndef CONFIG_MMU
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if (order > 0)
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for (i = 1 ; i < (1 << order) ; ++i)
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@ -404,8 +408,12 @@ void __free_pages_ok(struct page *page, unsigned int order)
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#endif
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for (i = 0 ; i < (1 << order) ; ++i)
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free_pages_check(__FUNCTION__, page + i);
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reserved += free_pages_check(__FUNCTION__, page + i);
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if (reserved)
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return;
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list_add(&page->lru, &list);
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mod_page_state(pgfree, 1 << order);
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kernel_map_pages(page, 1<<order, 0);
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free_pages_bulk(page_zone(page), 1, &list, order);
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}
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@ -463,7 +471,7 @@ void set_page_refs(struct page *page, int order)
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/*
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* This page is about to be returned from the page allocator
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*/
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static void prep_new_page(struct page *page, int order)
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static int prep_new_page(struct page *page, int order)
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{
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if ( page_mapcount(page) ||
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page->mapping != NULL ||
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@ -481,12 +489,20 @@ static void prep_new_page(struct page *page, int order)
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1 << PG_reserved )))
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bad_page(__FUNCTION__, page);
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/*
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* For now, we report if PG_reserved was found set, but do not
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* clear it, and do not allocate the page: as a safety net.
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*/
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if (PageReserved(page))
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return 1;
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page->flags &= ~(1 << PG_uptodate | 1 << PG_error |
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1 << PG_referenced | 1 << PG_arch_1 |
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1 << PG_checked | 1 << PG_mappedtodisk);
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set_page_private(page, 0);
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set_page_refs(page, order);
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kernel_map_pages(page, 1 << order, 1);
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return 0;
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}
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/*
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@ -669,11 +685,14 @@ static void fastcall free_hot_cold_page(struct page *page, int cold)
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arch_free_page(page, 0);
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kernel_map_pages(page, 1, 0);
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inc_page_state(pgfree);
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if (PageAnon(page))
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page->mapping = NULL;
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free_pages_check(__FUNCTION__, page);
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if (free_pages_check(__FUNCTION__, page))
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return;
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inc_page_state(pgfree);
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kernel_map_pages(page, 1, 0);
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pcp = &zone_pcp(zone, get_cpu())->pcp[cold];
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local_irq_save(flags);
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list_add(&page->lru, &pcp->list);
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@ -712,12 +731,14 @@ static struct page *
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buffered_rmqueue(struct zone *zone, int order, gfp_t gfp_flags)
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{
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unsigned long flags;
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struct page *page = NULL;
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struct page *page;
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int cold = !!(gfp_flags & __GFP_COLD);
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again:
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if (order == 0) {
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struct per_cpu_pages *pcp;
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page = NULL;
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pcp = &zone_pcp(zone, get_cpu())->pcp[cold];
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local_irq_save(flags);
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if (pcp->count <= pcp->low)
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@ -739,7 +760,8 @@ buffered_rmqueue(struct zone *zone, int order, gfp_t gfp_flags)
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if (page != NULL) {
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BUG_ON(bad_range(zone, page));
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mod_page_state_zone(zone, pgalloc, 1 << order);
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prep_new_page(page, order);
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if (prep_new_page(page, order))
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goto again;
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if (gfp_flags & __GFP_ZERO)
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prep_zero_page(page, order, gfp_flags);
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