slub: delay ctor until the object is requested

It seems that allocation of plenty objects causes latency on ARM since that
code can not be preempted

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/mm/slub.c b/mm/slub.c
index b1c50f7..a164648 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1363,8 +1363,10 @@ static void setup_object(struct kmem_cache *s, struct page *page,
 				void *object)
 {
 	setup_object_debug(s, page, object);
+#ifndef CONFIG_PREEMPT_RT_FULL
 	if (unlikely(s->ctor))
 		s->ctor(object);
+#endif
 }
 
 static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
@@ -2470,6 +2472,10 @@ redo:
 
 	if (unlikely(gfpflags & __GFP_ZERO) && object)
 		memset(object, 0, s->object_size);
+#ifdef CONFIG_PREEMPT_RT_FULL
+	if (unlikely(s->ctor) && object)
+		s->ctor(object);
+#endif
 
 	slab_post_alloc_hook(s, gfpflags, object);