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[PATCH] mm: VM_BUG_ON

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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
2006-09-25 23:30:55 -07:00
committed by Linus Torvalds
parent a6ca1b99ed
commit 725d704eca
5 changed files with 36 additions and 29 deletions
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10
include/linux/mm.h
View File

@@ -278,6 +278,12 @@ struct page {
*/
#include <linux/page-flags.h>
#ifdef CONFIG_DEBUG_VM
#define VM_BUG_ON(cond) BUG_ON(cond)
#else
#define VM_BUG_ON(condition) do { } while(0)
#endif
/*
* Methods to modify the page usage count.
*
@@ -297,7 +303,7 @@ struct page {
*/
static inline int put_page_testzero(struct page *page)
{
BUG_ON(atomic_read(&page->_count) == 0);
VM_BUG_ON(atomic_read(&page->_count) == 0);
return atomic_dec_and_test(&page->_count);
}
@@ -307,6 +313,7 @@ static inline int put_page_testzero(struct page *page)
*/
static inline int get_page_unless_zero(struct page *page)
{
VM_BUG_ON(PageCompound(page));
return atomic_inc_not_zero(&page->_count);
}
@@ -323,6 +330,7 @@ static inline void get_page(struct page *page)
{
if (unlikely(PageCompound(page)))
page = (struct page *)page_private(page);
VM_BUG_ON(atomic_read(&page->_count) == 0);
atomic_inc(&page->_count);
}