From: Andrew Morton <akpm@linux-foundation.org>
To: Dan Streetman <ddstreet@ieee.org>
Cc: Linux-MM <linux-mm@kvack.org>,
Seth Jennings <sjenning@redhat.com>,
Michal Hocko <mhocko@kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Minchan Kim <minchan@kernel.org>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Dan Streetman <dan.streetman@canonical.com>
Subject: Re: [PATCH 1/3] zswap: disable changing params if init fails
Date: Tue, 24 Jan 2017 13:24:41 -0800 [thread overview]
Message-ID: <20170124132441.5027560693ed6d8c283c1953@linux-foundation.org> (raw)
In-Reply-To: <20170124200259.16191-2-ddstreet@ieee.org>
On Tue, 24 Jan 2017 15:02:57 -0500 Dan Streetman <ddstreet@ieee.org> wrote:
> Add zswap_init_failed bool that prevents changing any of the module
> params, if init_zswap() fails, and set zswap_enabled to false. Change
> 'enabled' param to a callback, and check zswap_init_failed before
> allowing any change to 'enabled', 'zpool', or 'compressor' params.
>
> Any driver that is built-in to the kernel will not be unloaded if its
> init function returns error, and its module params remain accessible for
> users to change via sysfs. Since zswap uses param callbacks, which
> assume that zswap has been initialized, changing the zswap params after
> a failed initialization will result in WARNING due to the param callbacks
> expecting a pool to already exist. This prevents that by immediately
> exiting any of the param callbacks if initialization failed.
>
> This was reported here:
> https://marc.info/?l=linux-mm&m=147004228125528&w=4
I added Marcin's reportde-by to the changelog.
> And fixes this WARNING:
> [ 429.723476] WARNING: CPU: 0 PID: 5140 at mm/zswap.c:503
> __zswap_pool_current+0x56/0x60
>
> Fixes: 90b0fc26d5db ("zswap: change zpool/compressor at runtime")
> Cc: stable@vger.kernel.org
Is this really serious enough to justify a -stable backport? It's just
a bit of extra noise associated with an initialization problem which
the user will be fixing anyway.
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next prev parent reply other threads:[~2017-01-24 21:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 20:02 [PATCH 0/3] Fix zswap init failure behavior Dan Streetman
2017-01-24 20:02 ` [PATCH 1/3] zswap: disable changing params if init fails Dan Streetman
2017-01-24 21:24 ` Andrew Morton [this message]
2017-01-24 22:12 ` Dan Streetman
2017-01-24 20:02 ` [PATCH 2/3] zswap: allow initialization at boot without pool Dan Streetman
2017-01-25 0:24 ` Sergey Senozhatsky
2017-01-25 16:36 ` Dan Streetman
2017-01-24 20:02 ` [PATCH 3/3] zswap: clear compressor or zpool param if invalid at init Dan Streetman
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