mm, sl[au]b: print gfp_flags as strings in slab_out_of_memory()

We can now print gfp_flags more human-readable.  Make use of this in
slab_out_of_memory() for SLUB and SLAB.  Also convert the SLAB variant
it to pr_warn() along the way.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slab.c

@@ -1350,10 +1350,9 @@ slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
 	if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slab_oom_rs))
 		return;
 
-	printk(KERN_WARNING
-		"SLAB: Unable to allocate memory on node %d (gfp=0x%x)\n",
-		nodeid, gfpflags);
-	printk(KERN_WARNING "  cache: %s, object size: %d, order: %d\n",
+	pr_warn("SLAB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
+		nodeid, gfpflags, &gfpflags);
+	pr_warn("  cache: %s, object size: %d, order: %d\n",
 		cachep->name, cachep->size, cachep->gfporder);
 
 	for_each_kmem_cache_node(cachep, node, n) {
@@ -1377,8 +1376,7 @@ slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
 
 		num_slabs += active_slabs;
 		num_objs = num_slabs * cachep->num;
-		printk(KERN_WARNING
-			"  node %d: slabs: %ld/%ld, objs: %ld/%ld, free: %ld\n",
+		pr_warn("  node %d: slabs: %ld/%ld, objs: %ld/%ld, free: %ld\n",
 			node, active_slabs, num_slabs, active_objs, num_objs,
 			free_objects);
 	}

mm/slub.c

@@ -2236,8 +2236,8 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
 	if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs))
 		return;
 
-	pr_warn("SLUB: Unable to allocate memory on node %d (gfp=0x%x)\n",
-		nid, gfpflags);
+	pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
+		nid, gfpflags, &gfpflags);
 	pr_warn("  cache: %s, object size: %d, buffer size: %d, default order: %d, min order: %d\n",
 		s->name, s->object_size, s->size, oo_order(s->oo),
 		oo_order(s->min));