From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754782AbcBPKAb (ORCPT ); Tue, 16 Feb 2016 05:00:31 -0500 Received: from mga11.intel.com ([192.55.52.93]:45667 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754745AbcBPKA2 (ORCPT ); Tue, 16 Feb 2016 05:00:28 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,454,1449561600"; d="scan'208";a="652829810" Date: Tue, 16 Feb 2016 13:00:23 +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 13/28] thp: support file pages in zap_huge_pmd() Message-ID: <20160216100023.GC46557@black.fi.intel.com> References: <1455200516-132137-1-git-send-email-kirill.shutemov@linux.intel.com> <1455200516-132137-14-git-send-email-kirill.shutemov@linux.intel.com> <56BE2581.6070901@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56BE2581.6070901@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 10:33:37AM -0800, Dave Hansen wrote: > On 02/11/2016 06:21 AM, Kirill A. Shutemov wrote: > > For file pages we don't deposit page table on mapping: no need to > > withdraw it. > > I thought the deposit thing was to guarantee we could always do a PMD > split. It still seems like if you wanted to split a huge-tmpfs page, > you'd need to first split the PMD which might need the deposited one. > > Why not? For file thp, split_huge_pmd() is implemented by clearing out the pmd: we can setup and fill pte table later. Therefore no need to deposit page table -- we would not use it. DAX does the same. -- Kirill A. Shutemov