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Date: Thu, 2 Oct 2014 09:10:42 -0700
Message-ID: <CA+55aFx_Q7C2a9yCAqK=yWNX1mkcVRdE2bnLOQPHEkMjRcj7KQ@mail.gmail.com>
Subject: Re: pipe/page fault oddness.
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Hugh Dickins <hughd@google.com>, Dave Jones <davej@redhat.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@redhat.com>,
        Michel Lespinasse <walken@google.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Mel Gorman <mgorman@suse.de>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org

On Thu, Oct 2, 2014 at 8:04 AM, Sasha Levin <sasha.levin@oracle.com> wrote:
>
> I have a new one for you. I know it doesn't say "numa" anywhere, but I
> haven't ever seen that trace before so I'll just go ahead and blame it
> on your patch...

Fair enough, but the oops doesn't really give even a hint of what
could be wrong.

The stack is clearly too deep:

  Thread overran stack, or stack corrupted
  task.ti: ffff880dba2ec000
    RSP: ffff880dba2ebf48

but my patch shouldn't have added any deeper call-chains anywhere.

Anyway, unless you can get some other interesting oops with more hints
about where we go wrong, you might want to try Mel's four cleanup
patches instead. I love how you're testing my quick-and-dirty hack,
and I think we'll need to do this eventually, but in the short term
Mel's patches are probably worth applying.

In particular, his 4/4 patch removes the code case that I was
particularly nervous about, so it looks worth a try, because that may
just remove the bug with much smaller effort.

               Linus
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