From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] slab_common: clear pointers to per memcg caches on destroy
Date: Fri, 9 Oct 2015 11:08:36 +0300 [thread overview]
Message-ID: <20151009080835.GC2302@esperanza> (raw)
In-Reply-To: <20151008141735.d545d3fa1ab0244f69c41cdf@linux-foundation.org>
On Thu, Oct 08, 2015 at 02:17:35PM -0700, Andrew Morton wrote:
> On Thu, 8 Oct 2015 19:02:40 +0300 Vladimir Davydov <vdavydov@virtuozzo.com> wrote:
>
> > Currently, we do not clear pointers to per memcg caches in the
> > memcg_params.memcg_caches array when a global cache is destroyed with
> > kmem_cache_destroy. It is fine if the global cache does get destroyed.
> > However, a cache can be left on the list if it still has active objects
> > when kmem_cache_destroy is called (due to a memory leak). If this
> > happens, the entries in the array will point to already freed areas,
> > which is likely to result in data corruption when the cache is reused
> > (via slab merging).
>
> It's important that we report these leaks so the kernel bug can get
> fixed. The patch doesn't add such detection and reporting, but it
> could do so?
Reporting individual leaks is up to the slab implementation, we simply
can't do it from the generic code, so we just warn that there is a leak
there. SLUB already dumps addresses of all leaked objects to the log
(see kmem_cache_close -> free_partial -> list_slab_objects).
Thanks,
Vladimir
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next prev parent reply other threads:[~2015-10-09 8:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-08 16:02 [PATCH 1/3] slab_common: rename cache create/destroy helpers Vladimir Davydov
2015-10-08 16:02 ` [PATCH 2/3] slab_common: clear pointers to per memcg caches on destroy Vladimir Davydov
2015-10-08 21:17 ` Andrew Morton
2015-10-09 8:08 ` Vladimir Davydov [this message]
2015-10-08 16:02 ` [PATCH 3/3] slab_common: do not warn that cache is busy on destroy more than once Vladimir Davydov
2015-10-08 16:54 ` [PATCH 1/3] slab_common: rename cache create/destroy helpers Christoph Lameter
2015-10-14 2:35 ` David Rientjes
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