linux-kernel - Re: [PATCH] zram: Failing to decompress is WARN

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Message-ID: <20200918144623.GA748396@google.com>
Date:   Fri, 18 Sep 2020 07:46:23 -0700
From:   Minchan Kim <minchan@...nel.org>
To:     Douglas Anderson <dianders@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Nitin Gupta <ngupta@...are.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        sonnyrao@...omium.org, Jens Axboe <axboe@...nel.dk>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] zram: Failing to decompress is WARN_ON worthy

On Thu, Sep 17, 2020 at 05:41:20PM -0700, Douglas Anderson wrote:
> If we fail to decompress in zram it's a pretty serious problem.  We
> were entrusted to be able to decompress the old data but we failed.
> Either we've got some crazy bug in the compression code or we've got
> memory corruption.
> 
> At the moment, when this happens the log looks like this:
> 
>   ERR kernel: [ 1833.099861] zram: Decompression failed! err=-22, page=336112
>   ERR kernel: [ 1833.099881] zram: Decompression failed! err=-22, page=336112
>   ALERT kernel: [ 1833.099886] Read-error on swap-device (253:0:2688896)
> 
> It is true that we have an "ALERT" level log in there, but (at least
> to me) it feels like even this isn't enough to impart the seriousness
> of this error.  Let's convert to a WARN_ON.  Note that WARN_ON is
> automatically "unlikely" so we can simply replace the old annotation
> with the new one.
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
Acked-by: Minchan Kim <minchan@...nel.org>