From: Christoph Lameter <clameter@engr.sgi.com>
To: akpm@osdl.org
Cc: linux-mm@kvack.org
Subject: Fix drain_array() so that it works correctly with the shared_array
Date: Mon, 6 Mar 2006 19:20:11 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.64.0603061916110.28448@schroedinger.engr.sgi.com> (raw)
The list_lock also protects the shared array and we call drain_array()
with the shared array. Therefore we cannot go as far as I wanted to
but have to take the lock in a way so that it also protects the
array_cache in drain_pages.
(Note: maybe we should make the array_cache locking more consistent? I.e.
always take the array cache lock for shared arrays and disable interrupts
for the per cpu arrays?)
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Index: linux-2.6.16-rc5-mm2/mm/slab.c
===================================================================
--- linux-2.6.16-rc5-mm2.orig/mm/slab.c 2006-03-06 17:41:06.000000000 -0800
+++ linux-2.6.16-rc5-mm2/mm/slab.c 2006-03-06 19:15:08.000000000 -0800
@@ -3554,7 +3554,8 @@ static void enable_cpucache(struct kmem_
/*
* Drain an array if it contains any elements taking the l3 lock only if
- * necessary.
+ * necessary. Note that the l3 listlock also protects the array_cache
+ * if drain_array() is used on the shared array.
*/
void drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,
struct array_cache *ac, int force, int node)
@@ -3566,16 +3567,18 @@ void drain_array(struct kmem_cache *cach
if (ac->touched && !force) {
ac->touched = 0;
- } else if (ac->avail) {
- tofree = force ? ac->avail : (ac->limit + 4) / 5;
- if (tofree > ac->avail)
- tofree = (ac->avail + 1) / 2;
+ } else {
spin_lock_irq(&l3->list_lock);
- free_block(cachep, ac->entry, tofree, node);
+ if (ac->avail) {
+ tofree = force ? ac->avail : (ac->limit + 4) / 5;
+ if (tofree > ac->avail)
+ tofree = (ac->avail + 1) / 2;
+ free_block(cachep, ac->entry, tofree, node);
+ ac->avail -= tofree;
+ memmove(ac->entry, &(ac->entry[tofree]),
+ sizeof(void *) * ac->avail);
+ }
spin_unlock_irq(&l3->list_lock);
- ac->avail -= tofree;
- memmove(ac->entry, &(ac->entry[tofree]),
- sizeof(void *) * ac->avail);
}
}
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reply other threads:[~2006-03-07 3:20 UTC|newest]
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