linux-kernel - Re: [PATCH] Fix SLAB freelist randomization duplicate entries

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Message-ID: <CAJcbSZFczQ+DDAOLnMf9OpGfKZeuszMr6ObWTw=yL=khPPkxaw@mail.gmail.com>
Date:   Fri, 6 Jan 2017 13:41:29 -0800
From:   Thomas Garnier <thgarnie@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        John Sperbeck <jsperbeck@...gle.com>
Subject: Re: [PATCH] Fix SLAB freelist randomization duplicate entries

On Fri, Jan 6, 2017 at 12:42 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Fri, 6 Jan 2017 09:58:48 -0800 Thomas Garnier <thgarnie@...gle.com> wrote:
>
>> On Thu, Jan 5, 2017 at 4:35 PM, Andrew Morton <akpm@...ux-foundation.org> wrote:
>> > On Tue,  3 Jan 2017 10:19:08 -0800 Thomas Garnier <thgarnie@...gle.com> wrote:
>> >
>> >> This patch fixes a bug in the freelist randomization code. When a high
>> >> random number is used, the freelist will contain duplicate entries. It
>> >> will result in different allocations sharing the same chunk.
>> >
>> > Important: what are the user-visible runtime effects of the bug?
>>
>> It will result in odd behaviours and crashes. It should be uncommon
>> but it depends on the machines. We saw it happening more often on some
>> machines (every few hours of running tests).
>
> So should the fix be backported into -stable kernels?
>

I think it should, yes.

>> >
>> >> Fixes: c7ce4f60ac19 ("mm: SLAB freelist randomization")
>> >> Signed-off-by: John Sperbeck <jsperbeck@...gle.com>
>> >> Reviewed-by: Thomas Garnier <thgarnie@...gle.com>
>> >
>> > This should have been signed off by yourself.
>> >
>> > I'm guessing that the author was in fact John?  If so, you should
>> > indicate this by putting his From: line at the start of the changelog.
>> > Otherwise, authorship will default to the sender (ie, yourself).
>> >
>>
>> Sorry, I though the sign-off was enough. Do you want me to send a v2?
>
> I have the patch as
>
> From: John Sperbeck <jsperbeck@...gle.com>
> Signed-off-by: John Sperbeck <jsperbeck@...gle.com>
> Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
>
> Is that correct?  Is John the primary author?

That's correct.

-- 
Thomas