linux-kernel - Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common path

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Message-ID: <20161110091207.GB9173@hori1.linux.bs1.fc.nec.co.jp>
Date:   Thu, 10 Nov 2016 09:12:07 +0000
From:   Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:     Anshuman Khandual <khandual@...ux.vnet.ibm.com>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Hugh Dickins <hughd@...gle.com>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Michal Hocko <mhocko@...nel.org>,
        "Vlastimil Babka" <vbabka@...e.cz>,
        Pavel Emelyanov <xemul@...allels.com>,
        Zi Yan <zi.yan@...rutgers.edu>,
        Balbir Singh <bsingharora@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Naoya Horiguchi" <nao.horiguchi@...il.com>
Subject: Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common
 path

On Thu, Nov 10, 2016 at 02:06:14PM +0530, Anshuman Khandual wrote:
> On 11/08/2016 05:01 AM, Naoya Horiguchi wrote:
> > If one of callers of page migration starts to handle thp, memory management code
> > start to see pmd migration entry, so we need to prepare for it before enabling.
> > This patch changes various code point which checks the status of given pmds in
> > order to prevent race between thp migration and the pmd-related works.
> 
> There are lot of changes in this one patch. Should not we split
> this up into multiple patches and explain them in a bit detail
> through their commit messages ?

Yes, and I admit that I might change more than necessary, if the context
never encounters migration entry for any reason, no change is needed.
I'll dig more detail.

- Naoya Horiguchi