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Date: Thu, 28 Apr 2016 15:16:47 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Dan Streetman <ddstreet@ieee.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Seth Jennings <sjenning@redhat.com>, Yu Zhao <yuzhao@google.com>,
        Minchan Kim <minchan@kernel.org>, Nitin Gupta <ngupta@vflare.org>,
        Linux-MM <linux-mm@kvack.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Dan Streetman <dan.streetman@canonical.com>
Subject: Re: [PATCH] mm/zswap: provide unique zpool name
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On Thu, 28 Apr 2016 05:13:23 -0400 Dan Streetman <ddstreet@ieee.org> wrote:

> Instead of using "zswap" as the name for all zpools created, add
> an atomic counter and use "zswap%x" with the counter number for each
> zpool created, to provide a unique name for each new zpool.
> 
> As zsmalloc, one of the zpool implementations, requires/expects a
> unique name for each pool created, zswap should provide a unique name.
> The zsmalloc pool creation does not fail if a new pool with a
> conflicting name is created, unless CONFIG_ZSMALLOC_STAT is enabled;
> in that case, zsmalloc pool creation fails with -ENOMEM.  Then zswap
> will be unable to change its compressor parameter if its zpool is
> zsmalloc; it also will be unable to change its zpool parameter back
> to zsmalloc, if it has any existing old zpool using zsmalloc with
> page(s) in it.  Attempts to change the parameters will result in
> failure to create the zpool.  This changes zswap to provide a
> unique name for each zpool creation.
> 
> Fixes: f1c54846ee45 ("zswap: dynamic pool creation")

September 2015.  I added a cc:stable to this one.

> Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> Cc: Dan Streetman <dan.streetman@canonical.com>
> Signed-off-by: Dan Streetman <ddstreet@ieee.org>