mm, slub: allocate private object map for validate_slab_cache()

validate_slab_cache() is called either to handle a sysfs write, or from a
self-test context. In both situations it's straightforward to preallocate a
private object bitmap instead of grabbing the shared static one meant for
critical sections, so let's do that.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>

mm/slub.c

@@ -4679,11 +4679,11 @@ static int count_total(struct page *page)
 #endif
 
 #ifdef CONFIG_SLUB_DEBUG
-static void validate_slab(struct kmem_cache *s, struct page *page)
+static void validate_slab(struct kmem_cache *s, struct page *page,
+			  unsigned long *obj_map)
 {
 	void *p;
 	void *addr = page_address(page);
-	unsigned long *map;
 
 	slab_lock(page);
 
@@ -4691,21 +4691,20 @@ static void validate_slab(struct kmem_cache *s, struct page *page)
 		goto unlock;
 
 	/* Now we know that a valid freelist exists */
-	map = get_map(s, page);
+	__fill_map(obj_map, s, page);
 	for_each_object(p, s, addr, page->objects) {
-		u8 val = test_bit(__obj_to_index(s, addr, p), map) ?
+		u8 val = test_bit(__obj_to_index(s, addr, p), obj_map) ?
 			 SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;
 
 		if (!check_object(s, page, p, val))
 			break;
 	}
-	put_map(map);
 unlock:
 	slab_unlock(page);
 }
 
 static int validate_slab_node(struct kmem_cache *s,
-		struct kmem_cache_node *n)
+		struct kmem_cache_node *n, unsigned long *obj_map)
 {
 	unsigned long count = 0;
 	struct page *page;
@@ -4714,7 +4713,7 @@ static int validate_slab_node(struct kmem_cache *s,
 	spin_lock_irqsave(&n->list_lock, flags);
 
 	list_for_each_entry(page, &n->partial, slab_list) {
-		validate_slab(s, page);
+		validate_slab(s, page, obj_map);
 		count++;
 	}
 	if (count != n->nr_partial) {
@@ -4727,7 +4726,7 @@ static int validate_slab_node(struct kmem_cache *s,
 		goto out;
 
 	list_for_each_entry(page, &n->full, slab_list) {
-		validate_slab(s, page);
+		validate_slab(s, page, obj_map);
 		count++;
 	}
 	if (count != atomic_long_read(&n->nr_slabs)) {
@@ -4746,10 +4745,17 @@ long validate_slab_cache(struct kmem_cache *s)
 	int node;
 	unsigned long count = 0;
 	struct kmem_cache_node *n;
+	unsigned long *obj_map;
+
+	obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
+	if (!obj_map)
+		return -ENOMEM;
 
 	flush_all(s);
 	for_each_kmem_cache_node(s, node, n)
-		count += validate_slab_node(s, n);
+		count += validate_slab_node(s, n, obj_map);
+
+	bitmap_free(obj_map);
 
 	return count;
 }