Re: [PATCH 2/3] slab_common: clear pointers to per memcg caches on destroy

From: Andrew Morton
Date: Thu Oct 08 2015 - 17:17:47 EST


On Thu, 8 Oct 2015 19:02:40 +0300 Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> 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?

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