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 S1754007AbdF0Xho (ORCPT <rfc822;w@1wt.eu>);
        Tue, 27 Jun 2017 19:37:44 -0400
Received: from mail-lf0-f54.google.com ([209.85.215.54]:36599 "EHLO
        mail-lf0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1753939AbdF0Xhj (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 27 Jun 2017 19:37:39 -0400
MIME-Version: 1.0
In-Reply-To: <20170627181049.phlrtpkf3mqi4kt6@pd.tnic>
References: <20170502130453.5933-1-richard.weiyang@gmail.com>
 <20170502130453.5933-2-richard.weiyang@gmail.com> <20170626153149.b2x5pcipzuzaguuw@pd.tnic>
 <20170626231127.GA53180@WeideMacBook-Pro.local> <20170627181049.phlrtpkf3mqi4kt6@pd.tnic>
From: Wei Yang <richard.weiyang@gmail.com>
Date: Wed, 28 Jun 2017 07:37:16 +0800
Message-ID: <CADZGycYRFNKuJeySkt_dk+pFpvoR_0DT_xmWGcw=EH49gDpfwA@mail.gmail.com>
Subject: Re: [PATCH V2 1/3] x86/numa_emulation: fix potential memory leak
To: Borislav Petkov <bp@alien8.de>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Tejun Heo <tj@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Jun 28, 2017 at 2:10 AM, Borislav Petkov <bp@alien8.de> wrote:
> On Tue, Jun 27, 2017 at 07:11:27AM +0800, Wei Yang wrote:
>> It means numa emulation is not properly configured.
>
> Or what the error message says: it cannot determine the default physical
> node because NUMA emulation is not properly configured. What I'm trying
> to say, is, explain the *why* in the commit message, not the *what*. The
> *what* one can see in the code.
>

I didn't dig into the reason for when this could happen.

After some investigation, it looks will not happen after split_nodes_xxx()
works fine. In function split_nodes_xxx(), if it doesn't return an error code
it will set the emu_nid_to_phys[]. Which in turns be assigned to dfl_phys_nid.

So I suggest to remove the error branch.

>> Well, to this particular piece, have a for loop within a function doesn't look
>> like a big deal to me. So you prefer to take every for loop in this function
>> out?
>
> As I said, I'd prefer you take this loop out and turn it into a separate
> function in one go, along with fixing the potential memory leak.
>
>> Last but not the least, these are two issues:
>>
>> The problem this patch wants to address is the memory leak, while the concern
>> here you mentioned is the coding style.
>
> Let's not get too pedantic here: if you carve it out in a separate
> function, it is still clear what the patch is doing.
>

Ok, will do this.

> --
> Regards/Gruss,
>     Boris.
>
> Good mailing practices for 400: avoid top-posting and trim the reply.