linux-kernel - [PATCH -mm] slab: delete cache from list after __kmem_cache

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Date:	Thu, 15 May 2014 17:08:11 +0400
From:	Vladimir Davydov <vdavydov@...allels.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Pekka Enberg <penberg@...nel.org>
Subject: [PATCH -mm] slab: delete cache from list after __kmem_cache_shutdown succeeds

Currently, on kmem_cache_destroy we delete the cache from the slab_list
before __kmem_cache_shutdown, inserting it back to the list on failure.
Initially, this was done, because we could release the slab_mutex in
__kmem_cache_shutdown to delete sysfs slub entry, but since commit
41a212859a4d ("slub: use sysfs'es release mechanism for kmem_cache") we
remove sysfs entry later in kmem_cache_destroy after dropping the
slab_mutex, so that no implementation of __kmem_cache_shutdown can ever
release the lock. Therefore we can simplify the code a bit by moving
list_del after __kmem_cache_shutdown.

Signed-off-by: Vladimir Davydov <vdavydov@...allels.com>
Cc: Christoph Lameter <cl@...ux-foundation.org>
Cc: Pekka Enberg <penberg@...nel.org>
---
 mm/slab_common.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 48fafb61f35e..735e01a0db6f 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -346,15 +346,15 @@ void kmem_cache_destroy(struct kmem_cache *s)
 	if (memcg_cleanup_cache_params(s) != 0)
 		goto out_unlock;
 
-	list_del(&s->list);
 	if (__kmem_cache_shutdown(s) != 0) {
-		list_add(&s->list, &slab_caches);
 		printk(KERN_ERR "kmem_cache_destroy %s: "
 		       "Slab cache still has objects\n", s->name);
 		dump_stack();
 		goto out_unlock;
 	}
 
+	list_del(&s->list);
+
 	mutex_unlock(&slab_mutex);
 	if (s->flags & SLAB_DESTROY_BY_RCU)
 		rcu_barrier();
-- 
1.7.10.4

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