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* [patch 010/158] mm/slub.c: clean up validate_slab()
@ 2019-12-01  1:49 akpm
  0 siblings, 0 replies; only message in thread
From: akpm @ 2019-12-01  1:49 UTC (permalink / raw)
  To: akpm, cl, iamjoonsoo.kim, kirill.shutemov, linux-mm, mm-commits,
	penberg, penguin-kernel, rientjes, torvalds, yuzhao

From: Yu Zhao <yuzhao@google.com>
Subject: mm/slub.c: clean up validate_slab()

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.

Link: http://lkml.kernel.org/r/20191108193958.205102-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/slub.c |   21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

--- a/mm/slub.c~mm-clean-up-validate_slab
+++ a/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,
_


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2019-12-01  1:49 [patch 010/158] mm/slub.c: clean up validate_slab() akpm

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