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[PATCH] mm: VM_BUG_ON
Introduce a VM_BUG_ON, which is turned on with CONFIG_DEBUG_VM. Use this in the lightweight, inline refcounting functions; PageLRU and PageActive checks in vmscan, because they're pretty well confined to vmscan. And in page allocate/free fastpaths which can be the hottest parts of the kernel for kbuilds. Unlike BUG_ON, VM_BUG_ON must not be used to execute statements with side-effects, and should not be used outside core mm code. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin
Linus Torvalds
parent
a6ca1b99ed
commit
725d704eca
5 changed files with 36 additions and 29 deletions
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@ -278,6 +278,12 @@ struct page {
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*/
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#include <linux/page-flags.h>
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#ifdef CONFIG_DEBUG_VM
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#define VM_BUG_ON(cond) BUG_ON(cond)
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#else
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#define VM_BUG_ON(condition) do { } while(0)
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#endif
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/*
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* Methods to modify the page usage count.
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*
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@ -297,7 +303,7 @@ struct page {
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*/
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static inline int put_page_testzero(struct page *page)
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{
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BUG_ON(atomic_read(&page->_count) == 0);
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VM_BUG_ON(atomic_read(&page->_count) == 0);
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return atomic_dec_and_test(&page->_count);
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}
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@ -307,6 +313,7 @@ static inline int put_page_testzero(struct page *page)
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*/
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static inline int get_page_unless_zero(struct page *page)
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{
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VM_BUG_ON(PageCompound(page));
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return atomic_inc_not_zero(&page->_count);
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}
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@ -323,6 +330,7 @@ static inline void get_page(struct page *page)
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{
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if (unlikely(PageCompound(page)))
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page = (struct page *)page_private(page);
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VM_BUG_ON(atomic_read(&page->_count) == 0);
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atomic_inc(&page->_count);
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}
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@ -24,8 +24,8 @@ static inline void set_page_count(struct page *page, int v)
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*/
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static inline void set_page_refcounted(struct page *page)
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{
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BUG_ON(PageCompound(page) && page_private(page) != (unsigned long)page);
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BUG_ON(atomic_read(&page->_count));
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VM_BUG_ON(PageCompound(page) && page_private(page) != (unsigned long)page);
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VM_BUG_ON(atomic_read(&page->_count));
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set_page_count(page, 1);
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}
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@ -127,7 +127,6 @@ static int bad_range(struct zone *zone, struct page *page)
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return 0;
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}
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#else
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static inline int bad_range(struct zone *zone, struct page *page)
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{
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@ -218,12 +217,12 @@ static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
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{
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int i;
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BUG_ON((gfp_flags & (__GFP_WAIT | __GFP_HIGHMEM)) == __GFP_HIGHMEM);
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VM_BUG_ON((gfp_flags & (__GFP_WAIT | __GFP_HIGHMEM)) == __GFP_HIGHMEM);
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/*
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* clear_highpage() will use KM_USER0, so it's a bug to use __GFP_ZERO
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* and __GFP_HIGHMEM from hard or soft interrupt context.
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*/
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BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
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VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
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for (i = 0; i < (1 << order); i++)
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clear_highpage(page + i);
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}
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@ -347,8 +346,8 @@ static inline void __free_one_page(struct page *page,
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page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
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BUG_ON(page_idx & (order_size - 1));
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BUG_ON(bad_range(zone, page));
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VM_BUG_ON(page_idx & (order_size - 1));
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VM_BUG_ON(bad_range(zone, page));
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zone->free_pages += order_size;
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while (order < MAX_ORDER-1) {
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@ -421,7 +420,7 @@ static void free_pages_bulk(struct zone *zone, int count,
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while (count--) {
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struct page *page;
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BUG_ON(list_empty(list));
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VM_BUG_ON(list_empty(list));
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page = list_entry(list->prev, struct page, lru);
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/* have to delete it as __free_one_page list manipulates */
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list_del(&page->lru);
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@ -512,7 +511,7 @@ static inline void expand(struct zone *zone, struct page *page,
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area--;
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high--;
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size >>= 1;
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BUG_ON(bad_range(zone, &page[size]));
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VM_BUG_ON(bad_range(zone, &page[size]));
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list_add(&page[size].lru, &area->free_list);
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area->nr_free++;
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set_page_order(&page[size], high);
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@ -761,8 +760,8 @@ void split_page(struct page *page, unsigned int order)
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{
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int i;
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BUG_ON(PageCompound(page));
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BUG_ON(!page_count(page));
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VM_BUG_ON(PageCompound(page));
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VM_BUG_ON(!page_count(page));
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for (i = 1; i < (1 << order); i++)
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set_page_refcounted(page + i);
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}
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@ -809,7 +808,7 @@ again:
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local_irq_restore(flags);
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put_cpu();
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BUG_ON(bad_range(zone, page));
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VM_BUG_ON(bad_range(zone, page));
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if (prep_new_page(page, order, gfp_flags))
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goto again;
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return page;
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@ -1083,7 +1082,7 @@ fastcall unsigned long get_zeroed_page(gfp_t gfp_mask)
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* get_zeroed_page() returns a 32-bit address, which cannot represent
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* a highmem page
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*/
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BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);
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VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);
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page = alloc_pages(gfp_mask | __GFP_ZERO, 0);
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if (page)
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@ -1116,7 +1115,7 @@ EXPORT_SYMBOL(__free_pages);
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fastcall void free_pages(unsigned long addr, unsigned int order)
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{
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if (addr != 0) {
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BUG_ON(!virt_addr_valid((void *)addr));
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VM_BUG_ON(!virt_addr_valid((void *)addr));
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__free_pages(virt_to_page((void *)addr), order);
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}
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}
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12
mm/swap.c
12
mm/swap.c
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@ -233,7 +233,7 @@ void fastcall __page_cache_release(struct page *page)
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struct zone *zone = page_zone(page);
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spin_lock_irqsave(&zone->lru_lock, flags);
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BUG_ON(!PageLRU(page));
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VM_BUG_ON(!PageLRU(page));
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__ClearPageLRU(page);
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del_page_from_lru(zone, page);
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spin_unlock_irqrestore(&zone->lru_lock, flags);
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@ -284,7 +284,7 @@ void release_pages(struct page **pages, int nr, int cold)
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zone = pagezone;
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spin_lock_irq(&zone->lru_lock);
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}
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BUG_ON(!PageLRU(page));
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VM_BUG_ON(!PageLRU(page));
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__ClearPageLRU(page);
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del_page_from_lru(zone, page);
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}
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@ -337,7 +337,7 @@ void __pagevec_release_nonlru(struct pagevec *pvec)
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for (i = 0; i < pagevec_count(pvec); i++) {
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struct page *page = pvec->pages[i];
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BUG_ON(PageLRU(page));
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VM_BUG_ON(PageLRU(page));
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if (put_page_testzero(page))
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pagevec_add(&pages_to_free, page);
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}
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@ -364,7 +364,7 @@ void __pagevec_lru_add(struct pagevec *pvec)
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zone = pagezone;
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spin_lock_irq(&zone->lru_lock);
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}
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BUG_ON(PageLRU(page));
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VM_BUG_ON(PageLRU(page));
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SetPageLRU(page);
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add_page_to_inactive_list(zone, page);
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}
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@ -391,9 +391,9 @@ void __pagevec_lru_add_active(struct pagevec *pvec)
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zone = pagezone;
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spin_lock_irq(&zone->lru_lock);
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}
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BUG_ON(PageLRU(page));
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VM_BUG_ON(PageLRU(page));
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SetPageLRU(page);
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BUG_ON(PageActive(page));
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VM_BUG_ON(PageActive(page));
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SetPageActive(page);
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add_page_to_active_list(zone, page);
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}
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16
mm/vmscan.c
16
mm/vmscan.c
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@ -440,7 +440,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
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if (TestSetPageLocked(page))
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goto keep;
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BUG_ON(PageActive(page));
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VM_BUG_ON(PageActive(page));
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sc->nr_scanned++;
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@ -564,7 +564,7 @@ keep_locked:
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unlock_page(page);
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keep:
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list_add(&page->lru, &ret_pages);
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BUG_ON(PageLRU(page));
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VM_BUG_ON(PageLRU(page));
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}
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list_splice(&ret_pages, page_list);
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if (pagevec_count(&freed_pvec))
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@ -603,7 +603,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
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page = lru_to_page(src);
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prefetchw_prev_lru_page(page, src, flags);
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BUG_ON(!PageLRU(page));
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VM_BUG_ON(!PageLRU(page));
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list_del(&page->lru);
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target = src;
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@ -674,7 +674,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
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*/
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while (!list_empty(&page_list)) {
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page = lru_to_page(&page_list);
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BUG_ON(PageLRU(page));
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VM_BUG_ON(PageLRU(page));
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SetPageLRU(page);
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list_del(&page->lru);
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if (PageActive(page))
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@ -797,9 +797,9 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
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while (!list_empty(&l_inactive)) {
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page = lru_to_page(&l_inactive);
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prefetchw_prev_lru_page(page, &l_inactive, flags);
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BUG_ON(PageLRU(page));
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VM_BUG_ON(PageLRU(page));
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SetPageLRU(page);
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BUG_ON(!PageActive(page));
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VM_BUG_ON(!PageActive(page));
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ClearPageActive(page);
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list_move(&page->lru, &zone->inactive_list);
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@ -827,9 +827,9 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
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while (!list_empty(&l_active)) {
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page = lru_to_page(&l_active);
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prefetchw_prev_lru_page(page, &l_active, flags);
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BUG_ON(PageLRU(page));
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VM_BUG_ON(PageLRU(page));
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SetPageLRU(page);
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BUG_ON(!PageActive(page));
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VM_BUG_ON(!PageActive(page));
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list_move(&page->lru, &zone->active_list);
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pgmoved++;
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if (!pagevec_add(&pvec, page)) {
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