SLUB: simplify IRQ off handling

Move irq handling out of new slab into __slab_alloc.  That is useful for
Mathieu's cmpxchg_local patchset and also allows us to remove the crude
local_irq_off in early_kmem_cache_alloc().

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slub.c

@@ -1085,9 +1085,6 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 	BUG_ON(flags & GFP_SLAB_BUG_MASK);
 
-	if (flags & __GFP_WAIT)
-		local_irq_enable();
-
 	page = allocate_slab(s,
 		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
 	if (!page)
@@ -1120,8 +1117,6 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 	page->freelist = start;
 	page->inuse = 0;
 out:
-	if (flags & __GFP_WAIT)
-		local_irq_disable();
 	return page;
 }
 
@@ -1505,7 +1500,14 @@ new_slab:
 		goto load_freelist;
 	}
 
+	if (gfpflags & __GFP_WAIT)
+		local_irq_enable();
+
 	new = new_slab(s, gfpflags, node);
+
+	if (gfpflags & __GFP_WAIT)
+		local_irq_disable();
+
 	if (new) {
 		c = get_cpu_slab(s, smp_processor_id());
 		if (c->page) {
@@ -2039,12 +2041,6 @@ static struct kmem_cache_node *early_kmem_cache_node_alloc(gfp_t gfpflags,
 	init_kmem_cache_node(n);
 	atomic_long_inc(&n->nr_slabs);
 	add_partial(n, page);
-
-	/*
-	 * new_slab() disables interupts. If we do not reenable interrupts here
-	 * then bootup would continue with interrupts disabled.
-	 */
-	local_irq_enable();
 	return n;
 }