linux-kernel - Re: [Question] A novel case happened when using mempool allocate memory.

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Message-ID: <20180801153713.GA4039@bombadil.infradead.org>
Date:   Wed, 1 Aug 2018 08:37:13 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     zhong jiang <zhongjiang@...wei.com>
Cc:     Michal Hocko <mhocko@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        "mgorman@...hsingularity.net" <mgorman@...hsingularity.net>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Laura Abbott <labbott@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Question] A novel case happened when using mempool allocate
 memory.

On Wed, Aug 01, 2018 at 11:31:15PM +0800, zhong jiang wrote:
> Hi,  Everyone
> 
>  I ran across the following novel case similar to memory leak in linux-4.1 stable when allocating
>  memory object by kmem_cache_alloc.   it rarely can be reproduced.
> 
> I create a specific  mempool with 24k size based on the slab.  it can not be merged with
> other kmem cache.  I  record the allocation and free usage by atomic_add/sub.    After a while,
> I watch the specific slab consume most of total memory.   After halting the code execution.
> The counter of allocation and free is equal.  Therefore,  I am sure that module have released
> all meory resource.  but the statistic of specific slab is very high but stable by checking /proc/slabinfo.

Please post the code.