From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751697AbcDTX4g (ORCPT ); Wed, 20 Apr 2016 19:56:36 -0400 Received: from ozlabs.org ([103.22.144.67]:38285 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751450AbcDTX4f (ORCPT ); Wed, 20 Apr 2016 19:56:35 -0400 Date: Thu, 21 Apr 2016 09:56:33 +1000 From: Stephen Rothwell To: Hugh Dickins Cc: Andrew Morton , "Kirill A. Shutemov" , Andrea Arcangeli , Andres Lagar-Cavilla , Yang Shi , Ning Qu , kernel test robot , Xiong Zhou , Matthew Wilcox , Greg Thelen , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH mmotm 5/5] huge tmpfs: add shmem_pmd_fault() Message-ID: <20160421095633.3969f31d@canb.auug.org.au> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Hugh, On Sat, 16 Apr 2016 16:41:33 -0700 (PDT) Hugh Dickins wrote: > > The pmd_fault() method gives the filesystem an opportunity to place > a trans huge pmd entry at *pmd, before any pagetable is exposed (and > an opportunity to split it on COW fault): now use it for huge tmpfs. > > This patch is a little raw: with more time before LSF/MM, I would > probably want to dress it up better - the shmem_mapping() calls look > a bit ugly; it's odd to want FAULT_FLAG_MAY_HUGE and VM_FAULT_HUGE just > for a private conversation between shmem_fault() and shmem_pmd_fault(); > and there might be a better distribution of work between those two, but > prising apart that series of huge tests is not to be done in a hurry. > > Good for now, presents the new way, but might be improved later. > > This patch still leaves the huge tmpfs map_team_by_pmd() allocating a > pagetable while holding page lock, but other filesystems are no longer > doing so; and we've not yet settled whether huge tmpfs should (like anon > THP) or should not (like DAX) participate in deposit/withdraw protocol. > > Signed-off-by: Hugh Dickins > --- > I've been testing with this applied on top of mmotm plus 1-4/5, > but I suppose the right place for it is immediately after > huge-tmpfs-map-shmem-by-huge-page-pmd-or-by-page-team-ptes.patch > with a view to perhaps merging it into that in the future. > > mm/huge_memory.c | 4 ++-- > mm/memory.c | 13 +++++++++---- > mm/shmem.c | 33 +++++++++++++++++++++++++++++++++ > 3 files changed, 44 insertions(+), 6 deletions(-) I added this to the end of mmotm in linux-next today. -- Cheers, Stephen Rothwell