From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 18D096B0069 for ; Tue, 29 Nov 2016 03:53:37 -0500 (EST) Received: by mail-wm0-f71.google.com with SMTP id w13so42673720wmw.0 for ; Tue, 29 Nov 2016 00:53:37 -0800 (PST) Received: from mail-wj0-f196.google.com (mail-wj0-f196.google.com. [209.85.210.196]) by mx.google.com with ESMTPS id l6si1517070wmd.112.2016.11.29.00.45.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 29 Nov 2016 00:45:18 -0800 (PST) Received: by mail-wj0-f196.google.com with SMTP id kp2so17151343wjc.0 for ; Tue, 29 Nov 2016 00:45:18 -0800 (PST) Date: Tue, 29 Nov 2016 09:45:16 +0100 From: Michal Hocko Subject: Re: [PATCH v2 04/12] mm: thp: introduce CONFIG_ARCH_ENABLE_THP_MIGRATION Message-ID: <20161129084516.GB31671@dhcp22.suse.cz> References: <1478561517-4317-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1478561517-4317-5-git-send-email-n-horiguchi@ah.jp.nec.com> <20161128142154.GM14788@dhcp22.suse.cz> <20161129075006.GA15582@hori1.linux.bs1.fc.nec.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161129075006.GA15582@hori1.linux.bs1.fc.nec.co.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: "linux-mm@kvack.org" , "Kirill A. Shutemov" , Hugh Dickins , Andrew Morton , Dave Hansen , Andrea Arcangeli , Mel Gorman , Vlastimil Babka , Pavel Emelyanov , Zi Yan , Balbir Singh , "linux-kernel@vger.kernel.org" , Naoya Horiguchi On Tue 29-11-16 07:50:06, Naoya Horiguchi wrote: > On Mon, Nov 28, 2016 at 03:21:54PM +0100, Michal Hocko wrote: > > On Tue 08-11-16 08:31:49, Naoya Horiguchi wrote: > > > Introduces CONFIG_ARCH_ENABLE_THP_MIGRATION to limit thp migration > > > functionality to x86_64, which should be safer at the first step. > > > > Please make sure to describe why this has to be arch specific and what > > are arches supposed to provide in order to enable this option. > > OK, the below will be added in the future version: > > Thp migration is an arch-specific feature because it depends on the > arch-dependent behavior of non-present format of page table entry. > What you need to enable this option in other archs are: > - to define arch-specific transformation functions like __pmd_to_swp_entry() > and __swp_entry_to_pmd(), > - to make sure that arch-specific page table walking code can properly handle > !pmd_present case (gup_pmd_range() is a good example), > - (if your archs enables CONFIG_HAVE_ARCH_SOFT_DIRTY,) to define soft dirty > routines like pmd_swp_mksoft_dirty. Thanks this is _much_ better! -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org