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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 0BC1CC432C0 for ; Mon, 2 Dec 2019 08:54:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D17F320833 for ; Mon, 2 Dec 2019 08:54:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726339AbfLBIyg (ORCPT ); Mon, 2 Dec 2019 03:54:36 -0500 Received: from mga18.intel.com ([134.134.136.126]:29850 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726057AbfLBIyg (ORCPT ); Mon, 2 Dec 2019 03:54:36 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Dec 2019 00:54:35 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,268,1571727600"; d="scan'208";a="262153126" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by FMSMGA003.fm.intel.com with ESMTP; 02 Dec 2019 00:54:33 -0800 Date: Mon, 2 Dec 2019 16:54:27 +0800 From: Wei Yang To: "Kirill A. Shutemov" Cc: Wei Yang , Wei Yang , akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] mm/page_vma_mapped: use PMD_SIZE instead of calculating it Message-ID: <20191202085427.GA6656@richard> Reply-To: Wei Yang References: <20191128010321.21730-1-richardw.yang@linux.intel.com> <20191128083255.ab5rwj7gvktwunik@box.shutemov.name> <20191128212226.sfrhfs5m3q7m6tly@master> <20191202080315.oqtm3q7cyfkl5rma@box.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191202080315.oqtm3q7cyfkl5rma@box.shutemov.name> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 02, 2019 at 11:03:15AM +0300, Kirill A. Shutemov wrote: >On Thu, Nov 28, 2019 at 09:22:26PM +0000, Wei Yang wrote: >> On Thu, Nov 28, 2019 at 11:32:55AM +0300, Kirill A. Shutemov wrote: >> >On Thu, Nov 28, 2019 at 09:03:20AM +0800, Wei Yang wrote: >> >> At this point, we are sure page is PageTransHuge, which means >> >> hpage_nr_pages is HPAGE_PMD_NR. >> >> >> >> This is safe to use PMD_SIZE instead of calculating it. >> >> >> >> Signed-off-by: Wei Yang >> >> --- >> >> mm/page_vma_mapped.c | 2 +- >> >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> >> >> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c >> >> index eff4b4520c8d..76e03650a3ab 100644 >> >> --- a/mm/page_vma_mapped.c >> >> +++ b/mm/page_vma_mapped.c >> >> @@ -223,7 +223,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) >> >> if (pvmw->address >= pvmw->vma->vm_end || >> >> pvmw->address >= >> >> __vma_address(pvmw->page, pvmw->vma) + >> >> - hpage_nr_pages(pvmw->page) * PAGE_SIZE) >> >> + PMD_SIZE) >> >> return not_found(pvmw); >> >> /* Did we cross page table boundary? */ >> >> if (pvmw->address % PMD_SIZE == 0) { >> > >> >It is dubious cleanup. Maybe page_size(pvmw->page) instead? It will not >> >break if we ever get PUD THP pages. >> > >> >> Thanks for your comment. >> >> I took a look into the code again and found I may miss something. >> >> I found we support PUD THP pages, whilc hpage_nr_pages() just return >> HPAGE_PMD_NR on PageTransHuge. Why this is not possible to return PUD number? > >We only support PUD THP for DAX. Means, we don't have struct page for it. > Ok, many background story behind it. Thanks :-) >-- > Kirill A. Shutemov -- Wei Yang Help you, Help me