slab: use slab_pre_alloc_hook in SLAB allocator shared with SLUB

Deduplicate code in SLAB allocator functions slab_alloc() and
slab_alloc_node() by using the slab_pre_alloc_hook() call, which is now
shared between SLUB and SLAB.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.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: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slab.c

@@ -3144,14 +3144,10 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
 	int slab_node = numa_mem_id();
 
 	flags &= gfp_allowed_mask;
-
-	lockdep_trace_alloc(flags);
-
-	if (should_failslab(cachep, flags))
+	cachep = slab_pre_alloc_hook(cachep, flags);
+	if (unlikely(!cachep))
 		return NULL;
 
-	cachep = memcg_kmem_get_cache(cachep, flags);
-
 	cache_alloc_debugcheck_before(cachep, flags);
 	local_irq_save(save_flags);
 
@@ -3232,14 +3228,10 @@ slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
 	void *objp;
 
 	flags &= gfp_allowed_mask;
-
-	lockdep_trace_alloc(flags);
-
-	if (should_failslab(cachep, flags))
+	cachep = slab_pre_alloc_hook(cachep, flags);
+	if (unlikely(!cachep))
 		return NULL;
 
-	cachep = memcg_kmem_get_cache(cachep, flags);
-
 	cache_alloc_debugcheck_before(cachep, flags);
 	local_irq_save(save_flags);
 	objp = __do_cache_alloc(cachep, flags);