From: Minchan Kim <minchan@kernel.org>
To: Weijie Yang <weijie.yang@samsung.com>
Cc: akpm@linux-foundation.org, sjennings@variantweb.net,
bob.liu@oracle.com, weijie.yang.kh@gmail.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH RESEND 1/2] mm/zswap: bugfix: memory leak when invalidate and reclaim occur concurrently
Date: Fri, 25 Oct 2013 19:15:32 +0900 [thread overview]
Message-ID: <20131025101532.GD6612@gmail.com> (raw)
In-Reply-To: <000001ced09e$e3718180$aa548480$%yang@samsung.com>
On Thu, Oct 24, 2013 at 05:51:11PM +0800, Weijie Yang wrote:
> Consider the following scenario:
> thread 0: reclaim entry x (get refcount, but not call zswap_get_swap_cache_page)
> thread 1: call zswap_frontswap_invalidate_page to invalidate entry x.
> finished, entry x and its zbud is not freed as its refcount != 0
> now, the swap_map[x] = 0
> thread 0: now call zswap_get_swap_cache_page
> swapcache_prepare return -ENOENT because entry x is not used any more
> zswap_get_swap_cache_page return ZSWAP_SWAPCACHE_NOMEM
> zswap_writeback_entry do nothing except put refcount
> Now, the memory of zswap_entry x and its zpage leak.
>
> Modify:
> - check the refcount in fail path, free memory if it is not referenced.
>
> - use ZSWAP_SWAPCACHE_FAIL instead of ZSWAP_SWAPCACHE_NOMEM as the fail path
> can be not only caused by nomem but also by invalidate.
>
> Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
> Reviewed-by: Bob Liu <bob.liu@oracle.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: <stable@vger.kernel.org>
> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Thanks, Weijie!
--
Kind regards,
Minchan Kim
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prev parent reply other threads:[~2013-10-25 10:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-24 9:51 [PATCH RESEND 1/2] mm/zswap: bugfix: memory leak when invalidate and reclaim occur concurrently Weijie Yang
2013-10-25 10:15 ` Minchan Kim [this message]
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