From: Glauber Costa <glommer@parallels.com>
To: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>, Joonsoo Kim <js1304@gmail.com>,
linux-mm@kvack.org, David Rientjes <rientjes@google.com>
Subject: Re: C13 [08/14] Get rid of __kmem_cache_destroy
Date: Mon, 3 Sep 2012 18:58:15 +0400 [thread overview]
Message-ID: <5044C587.60801@parallels.com> (raw)
In-Reply-To: <000001395967d71c-8ea585e1-ebf1-43ac-a9e4-b3b89f7d64d9-000000@email.amazonses.com>
On 08/24/2012 08:12 PM, Christoph Lameter wrote:
> What is done there can be done in __kmem_cache_shutdown.
>
> This affects RCU handling somewhat. On rcu free all slab allocators
> do not refer to other management structures than the kmem_cache structure.
> Therefore these other structures can be freed before the rcu deferred
> free to the page allocator occurs.
>
> Reviewed-by: Joonsoo Kim <js1304@gmail.com>
> Signed-off-by: Christoph Lameter <cl@linux.com>
Here is the code for that in slab_common.c:
if (!__kmem_cache_shutdown(s)) {
if (s->flags & SLAB_DESTROY_BY_RCU)
rcu_barrier();
__kmem_cache_destroy(s);
} ...
All that code that used to belong in __kmem_cache_destroy(), will not be
executed in kmem_cache_shutdown() without an rcu_barrier.
You need at least Paul's ack here to guarantee it is safe, but I believe
it is not. Take a look for instance at 7ed9f7e5db5, which describes a
subtle bug arising from such a situation.
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next prev parent reply other threads:[~2012-09-03 15:01 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120824160903.168122683@linux.com>
2012-08-24 16:10 ` C13 [05/14] Extract a common function for kmem_cache_destroy Christoph Lameter
2012-09-03 14:41 ` Glauber Costa
2012-09-03 15:26 ` Glauber Costa
2012-09-04 22:58 ` Christoph Lameter
2012-08-24 16:12 ` C13 [07/14] Move freeing of kmem_cache structure to common code Christoph Lameter
2012-09-03 14:51 ` Glauber Costa
2012-08-24 16:12 ` C13 [08/14] Get rid of __kmem_cache_destroy Christoph Lameter
2012-09-03 14:58 ` Glauber Costa [this message]
2012-09-04 22:39 ` Christoph Lameter
2012-09-05 8:25 ` Glauber Costa
2012-08-24 16:17 ` C13 [03/14] Improve error handling in kmem_cache_create Christoph Lameter
2012-09-03 14:30 ` Glauber Costa
2012-08-24 16:17 ` C13 [12/14] Move kmem_cache allocations into common code Christoph Lameter
2012-09-03 15:24 ` Glauber Costa
2012-08-24 16:17 ` C13 [11/14] Move sysfs_slab_add to common Christoph Lameter
2012-09-03 15:09 ` Glauber Costa
2012-08-24 16:17 ` C13 [06/14] Always use the name "kmem_cache" for the slab cache with the kmem_cache structure Christoph Lameter
2012-08-24 16:17 ` C13 [04/14] Move list_add() to slab_common.c Christoph Lameter
2012-08-24 16:17 ` C13 [10/14] Do slab aliasing call from common code Christoph Lameter
2012-08-24 16:17 ` C13 [01/14] slub: Add debugging to verify correct cache use on kmem_cache_free() Christoph Lameter
2012-09-03 14:26 ` Glauber Costa
2012-08-24 16:17 ` C13 [09/14] Move duping of slab name to slab_common.c Christoph Lameter
2012-09-03 15:02 ` Glauber Costa
2012-08-24 16:17 ` C13 [14/14] Move kmem_cache refcounting to common code Christoph Lameter
2012-09-03 15:12 ` Glauber Costa
2012-09-04 19:10 ` Christoph Lameter
2012-08-24 16:17 ` C13 [13/14] Shrink __kmem_cache_create() parameter lists Christoph Lameter
2012-09-03 15:33 ` Glauber Costa
2012-09-03 15:35 ` Glauber Costa
2012-09-04 22:48 ` Christoph Lameter
2012-08-24 16:17 ` C13 [02/14] slub: Use kmem_cache for the kmem_cache structure Christoph Lameter
2012-09-03 14:27 ` Glauber Costa
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