From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1753158AbdF2Szk (ORCPT <rfc822;w@1wt.eu>);
        Thu, 29 Jun 2017 14:55:40 -0400
Received: from mx1.redhat.com ([209.132.183.28]:21816 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1752584AbdF2Szc (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 29 Jun 2017 14:55:32 -0400
DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com E452F7A188
Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com
Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=oleg@redhat.com
DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com E452F7A188
Date: Thu, 29 Jun 2017 20:55:28 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Larry Woodman <lwoodman@redhat.com>, Michal Hocko <mhocko@suse.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev
Message-ID: <20170629185528.GA1394@redhat.com>
References: <20170628175237.GA24868@redhat.com>
 <CA+55aFz0bvToQBMn+5_1+_OFDd-yNm3Tkt1tFBojwDHXsrHSHQ@mail.gmail.com>
 <20170629151901.GA32134@redhat.com>
 <CA+55aFyqR0gzfvGx027U4-ZyAYeFbf=cSu6n9bwc0kCTpY+HkA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CA+55aFyqR0gzfvGx027U4-ZyAYeFbf=cSu6n9bwc0kCTpY+HkA@mail.gmail.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 29 Jun 2017 18:55:32 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 06/29, Linus Torvalds wrote:
>
> On Thu, Jun 29, 2017 at 8:19 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > Hmm. May be you misread this patch?
>
> Ahh, yes. I'm ok with your patch.
>
> That said, you did remove something extra: the comment about
>
>     /* Check that both stack segments have the same anon_vma? */

I didn't ;) I moved it up, right above VM_GROWSDOWN check.


> is actually still relevant wrt that VM_GROWSDOWN test. The issue is
> that we could actually limit the VM_GROWSDOWN thing to only be ok with
> merging with a previous vma only if it *really* was the same segment.

Yes, yes, this is clear. This comment motivated me to ask that question,
I thought that we probably do not need to reconcile the stacks even in
this case.

Oleg.