slub: Extend init_on_alloc to slab caches with constructors

Signed-off-by: Thibaut Sautereau <[email protected]>
Signed-off-by: Levente Polyak <[email protected]>

Author: tsautereau-anssi

mm/slab.h

@@ -614,8 +614,10 @@ static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
 static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c)
 {
 	if (static_branch_unlikely(&init_on_alloc)) {
+#ifndef CONFIG_SLUB
 		if (c->ctor)
 			return false;
+#endif
 		if (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))
 			return flags & __GFP_ZERO;
 		return true;

mm/slub.c

@@ -1635,9 +1635,10 @@ static inline bool slab_free_freelist_hook(struct kmem_cache *s,
 			 * need to show a valid freepointer to check_object().
 			 *
 			 * Note that doing this for all caches (not just ctor
-			 * ones, which have s->offset != NULL)) causes a GPF,
-			 * due to KASAN poisoning and the way set_freepointer()
-			 * eventually dereferences the freepointer.
+			 * ones, which have s->offset >= object_size)) causes a
+			 * GPF, due to KASAN poisoning and the way
+			 * set_freepointer() eventually dereferences the
+			 * freepointer.
 			 */
 			set_freepointer(s, object, NULL);
 		}
@@ -2952,8 +2953,14 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s,
 		if (s->ctor)
 			s->ctor(object);
 		kasan_poison_object_data(s, object);
-	} else if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object)
+	} else if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object) {
 		memset(object, 0, s->object_size);
+		if (s->ctor) {
+			kasan_unpoison_object_data(s, object);
+			s->ctor(object);
+			kasan_poison_object_data(s, object);
+		}
+	}
 
 	if (object) {
 		check_canary(s, object, s->random_inactive);
@@ -3411,8 +3418,14 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 	} else if (unlikely(slab_want_init_on_alloc(flags, s))) {
 		int j;
 
-		for (j = 0; j < i; j++)
+		for (j = 0; j < i; j++) {
 			memset(p[j], 0, s->object_size);
+			if (s->ctor) {
+				kasan_unpoison_object_data(s, p[j]);
+				s->ctor(p[j]);
+				kasan_poison_object_data(s, p[j]);
+			}
+		}
 	}
 
 	for (k = 0; k < i; k++) {