linux-kernel - Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm

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Date:   Thu, 29 Jun 2017 20:55:28 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Hugh Dickins <hughd@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Larry Woodman <lwoodman@...hat.com>,
        Michal Hocko <mhocko@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev

On 06/29, Linus Torvalds wrote:
>
> On Thu, Jun 29, 2017 at 8:19 AM, Oleg Nesterov <oleg@...hat.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.