From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754820AbcBPKO4 (ORCPT ); Tue, 16 Feb 2016 05:14:56 -0500 Received: from mga04.intel.com ([192.55.52.120]:3680 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754453AbcBPKOy (ORCPT ); Tue, 16 Feb 2016 05:14:54 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,454,1449561600"; d="scan'208";a="903496760" Date: Tue, 16 Feb 2016 13:14:50 +0300 From: "Kirill A. Shutemov" To: Dave Hansen Cc: Hugh Dickins , Andrea Arcangeli , Andrew Morton , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Jerome Marchand , Yang Shi , Sasha Levin , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv2 17/28] thp: skip file huge pmd on copy_huge_pmd() Message-ID: <20160216101450.GE46557@black.fi.intel.com> References: <1455200516-132137-1-git-send-email-kirill.shutemov@linux.intel.com> <1455200516-132137-18-git-send-email-kirill.shutemov@linux.intel.com> <56BE2781.7060808@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56BE2781.7060808@intel.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 12, 2016 at 10:42:09AM -0800, Dave Hansen wrote: > On 02/11/2016 06:21 AM, Kirill A. Shutemov wrote: > > File pmds can be safely skip on copy_huge_pmd(), we can re-fault them > > later. COW for file mappings handled on pte level. > > Is this different from 4k pages? I figured we might skip copying > file-backed ptes on fork, but I couldn't find the code. Currently, we only filter out on per-VMA basis. See first comment in copy_page_range(). Here we handle PMD mapped file pages in COW mapping. File THP can be mapped into COW mapping as result of read page fault. -- Kirill A. Shutemov