From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E5C7C6778A for ; Mon, 9 Jul 2018 05:40:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61910208A3 for ; Mon, 9 Jul 2018 05:40:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 61910208A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754320AbeGIFku (ORCPT ); Mon, 9 Jul 2018 01:40:50 -0400 Received: from mga01.intel.com ([192.55.52.88]:52396 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750846AbeGIFkt (ORCPT ); Mon, 9 Jul 2018 01:40:49 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Jul 2018 22:40:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,329,1526367600"; d="scan'208";a="63225381" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.13.118]) by FMSMGA003.fm.intel.com with ESMTP; 08 Jul 2018 22:40:46 -0700 From: "Huang\, Ying" To: Dan Williams Cc: Andrew Morton , linux-mm , Linux Kernel Mailing List , "Kirill A. Shutemov" , Andrea Arcangeli , Michal Hocko , Johannes Weiner , Shaohua Li , , Minchan Kim , Rik van Riel , Dave Hansen , , , Subject: Re: [PATCH -mm -v4 01/21] mm, THP, swap: Enable PMD swap operations for CONFIG_THP_SWAP References: <20180622035151.6676-1-ying.huang@intel.com> <20180622035151.6676-2-ying.huang@intel.com> Date: Mon, 09 Jul 2018 13:40:45 +0800 In-Reply-To: (Dan Williams's message of "Sat, 7 Jul 2018 14:11:18 -0700") Message-ID: <87muv1kluq.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dan Williams writes: > On Thu, Jun 21, 2018 at 8:55 PM Huang, Ying wrote: >> >> From: Huang Ying >> >> Previously, the PMD swap operations are only enabled for >> CONFIG_ARCH_ENABLE_THP_MIGRATION. Because they are only used by the >> THP migration support. We will support PMD swap mapping to the huge >> swap cluster and swapin the THP as a whole. That will be enabled via >> CONFIG_THP_SWAP and needs these PMD swap operations. So enable the >> PMD swap operations for CONFIG_THP_SWAP too. >> >> Signed-off-by: "Huang, Ying" >> Cc: "Kirill A. Shutemov" >> Cc: Andrea Arcangeli >> Cc: Michal Hocko >> Cc: Johannes Weiner >> Cc: Shaohua Li >> Cc: Hugh Dickins >> Cc: Minchan Kim >> Cc: Rik van Riel >> Cc: Dave Hansen >> Cc: Naoya Horiguchi >> Cc: Zi Yan >> Cc: Daniel Jordan >> --- >> arch/x86/include/asm/pgtable.h | 2 +- >> include/asm-generic/pgtable.h | 2 +- >> include/linux/swapops.h | 44 ++++++++++++++++++++++-------------------- >> 3 files changed, 25 insertions(+), 23 deletions(-) >> >> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h >> index 99ecde23c3ec..13bf58838daf 100644 >> --- a/arch/x86/include/asm/pgtable.h >> +++ b/arch/x86/include/asm/pgtable.h >> @@ -1224,7 +1224,7 @@ static inline pte_t pte_swp_clear_soft_dirty(pte_t pte) >> return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY); >> } >> >> -#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION >> +#if defined(CONFIG_ARCH_ENABLE_THP_MIGRATION) || defined(CONFIG_THP_SWAP) > > How about introducing a new config symbol representing the common > infrastructure between the two and have them select that symbol. The common infrastructure shared by two mechanisms is PMD swap entry. But I didn't find there are many places where the common infrastructure is used. So I think it may be over-engineering to introduce a new config symbol but use it for so few times. > Would that also allow us to clean up the usage of > CONFIG_ARCH_ENABLE_THP_MIGRATION in fs/proc/task_mmu.c? In other > words, what's the point of having nice ifdef'd alternatives in header > files when ifdefs are still showing up in C files, all of it should be > optionally determined by header files. Unfortunately, I think it is not a easy task to wrap all C code via #ifdef in header files. And it may be over-engineering to wrap them all. I guess this is why there are still some #ifdef in C files. Best Regards, Huang, Ying