Re: [PATCH v3 1/2] mm: clean up validate_slab()

2019-09-16 Thread Kirill A. Shutemov
On Fri, Sep 13, 2019 at 06:07:42PM -0600, Yu Zhao wrote:
> The function doesn't need to return any value, and the check can be
> done in one pass.
> 
> There is a behavior change: before the patch, we stop at the first
> invalid free object; after the patch, we stop at the first invalid
> object, free or in use. This shouldn't matter because the original
> behavior isn't intended anyway.
> 
> Signed-off-by: Yu Zhao 

Acked-by: Kirill A. Shutemov 

-- 
 Kirill A. Shutemov


[PATCH v3 1/2] mm: clean up validate_slab()

2019-09-13 Thread Yu Zhao
The function doesn't need to return any value, and the check can be
done in one pass.

There is a behavior change: before the patch, we stop at the first
invalid free object; after the patch, we stop at the first invalid
object, free or in use. This shouldn't matter because the original
behavior isn't intended anyway.

Signed-off-by: Yu Zhao 
---
 mm/slub.c | 21 -
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 8834563cdb4b..445ef8b2aec0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4384,31 +4384,26 @@ static int count_total(struct page *page)
 #endif
 
 #ifdef CONFIG_SLUB_DEBUG
-static int validate_slab(struct kmem_cache *s, struct page *page,
+static void validate_slab(struct kmem_cache *s, struct page *page,
unsigned long *map)
 {
void *p;
void *addr = page_address(page);
 
-   if (!check_slab(s, page) ||
-   !on_freelist(s, page, NULL))
-   return 0;
+   if (!check_slab(s, page) || !on_freelist(s, page, NULL))
+   return;
 
/* Now we know that a valid freelist exists */
bitmap_zero(map, page->objects);
 
get_map(s, page, map);
for_each_object(p, s, addr, page->objects) {
-   if (test_bit(slab_index(p, s, addr), map))
-   if (!check_object(s, page, p, SLUB_RED_INACTIVE))
-   return 0;
-   }
+   u8 val = test_bit(slab_index(p, s, addr), map) ?
+SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;
 
-   for_each_object(p, s, addr, page->objects)
-   if (!test_bit(slab_index(p, s, addr), map))
-   if (!check_object(s, page, p, SLUB_RED_ACTIVE))
-   return 0;
-   return 1;
+   if (!check_object(s, page, p, val))
+   break;
+   }
 }
 
 static void validate_slab_slab(struct kmem_cache *s, struct page *page,
-- 
2.23.0.237.gc6a4ce50a0-goog