commit 80f08c191f6c9563641291bea80657a3b9faabf0
author Christoph Lameter <cl@linux.com> Wed Jun 01 12:25:55 2011 -0500
committer Pekka Enberg <penberg@kernel.org> Sat Jul 02 13:26:56 2011 +0300
tree 9ad3d121f6a6cd30e317b5819a0d8cb729e2b296
parent 5c2e4bbbd60623f1024a753c291b666068f8a6e7

slub: Avoid disabling interrupts in free slowpath

Disabling interrupts can be avoided now. However, list operation still require
disabling interrupts since allocations can occur from interrupt
contexts and there is no way to perform atomic list operations.

The acquition of the list_lock therefore has to disable interrupts as well.

Dropping interrupt handling significantly simplifies the slowpath.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

mm/slub.c

diff --git a/mm/slub.c b/mm/slub.c
index 08c57a0..cb6b085 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2197,11 +2197,10 @@
 	struct kmem_cache_node *n = NULL;
 	unsigned long uninitialized_var(flags);
 
-	local_irq_save(flags);
 	stat(s, FREE_SLOWPATH);
 
 	if (kmem_cache_debug(s) && !free_debug_processing(s, page, x, addr))
-		goto out_unlock;
+		return;
 
 	do {
 		prior = page->freelist;
@@ -2220,7 +2219,7 @@
 			 * Otherwise the list_lock will synchronize with
 			 * other processors updating the list of slabs.
 			 */
-                        spin_lock(&n->list_lock);
+                        spin_lock_irqsave(&n->list_lock, flags);
 		}
 		inuse = new.inuse;
 
@@ -2236,7 +2235,7 @@
 		 */
                 if (was_frozen)
                         stat(s, FREE_FROZEN);
-                goto out_unlock;
+                return;
         }
 
 	/*
@@ -2259,11 +2258,7 @@
 			stat(s, FREE_ADD_PARTIAL);
 		}
 	}
-
-	spin_unlock(&n->list_lock);
-
-out_unlock:
-	local_irq_restore(flags);
+	spin_unlock_irqrestore(&n->list_lock, flags);
 	return;
 
 slab_empty:
@@ -2275,8 +2270,7 @@
 		stat(s, FREE_REMOVE_PARTIAL);
 	}
 
-	spin_unlock(&n->list_lock);
-	local_irq_restore(flags);
+	spin_unlock_irqrestore(&n->list_lock, flags);
 	stat(s, FREE_SLAB);
 	discard_slab(s, page);
 }