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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 D50FCC433E0 for ; Mon, 6 Jul 2020 10:07:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B165020739 for ; Mon, 6 Jul 2020 10:07:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="chbzR/Sx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728670AbgGFKHb (ORCPT ); Mon, 6 Jul 2020 06:07:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728264AbgGFKHb (ORCPT ); Mon, 6 Jul 2020 06:07:31 -0400 Received: from mail-lj1-x243.google.com (mail-lj1-x243.google.com [IPv6:2a00:1450:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F4AFC061794 for ; Mon, 6 Jul 2020 03:07:31 -0700 (PDT) Received: by mail-lj1-x243.google.com with SMTP id b25so40968010ljp.6 for ; Mon, 06 Jul 2020 03:07:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=fRxJulFmu9AlNtElSO/F+8/ObuCR2DVnY3HV66MXZyY=; b=chbzR/SxWlB99qHfrUpK6zYZczJOJ30TTX03MKQMa7LI84LqiNpJ9ffCASF5R7JkiV lj/5c1LZ2KTWjVz+l+kskv6+DPaG4kGPrUUygrDYQAAAGZ2qaM/ubnhS0EEMWAhDg5Zr 26A5iTAqQG8/o6F4zuKDfxCwgJkLxRB6j/WHMyFUEyGjRoOis1qBllA0l/+OEYCmicDy zfJB9H1Fn6ehUyn/OP/sUkxNlM7oNgirW4/rVDDidSeP+lv7i+lNqEiEZTrELiYiiU/0 1XljSbRM2GcaECzu6TNqmYMPKaVYysl0aDjw7bNyVuZPW+4mnaqLun5uSrKwLpHkh/SX MWZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=fRxJulFmu9AlNtElSO/F+8/ObuCR2DVnY3HV66MXZyY=; b=UiCSf0loLmbGiyP+oQj2XCuDMNtoIGKXmfSrVycfpiIQV++N8u+czvZAoevQJhEnoP BjPpReAR1sSCDdniFIUGUvacmcMS+uEcSzHupUQmCPRHtlyLbyFYPQ3tE/F7fSIzhEUT vvPSLBjsfhl10Ppj8d/1W998myRyHT8fkFNAoeKfXCfwIpXsaW628nx5wibBw5tGIccr qPzFHCWLSaP1O/n9vhlInnsr96K5vU6kjBFbvlH9L2YhIt6HIXxXM47fBTH+fc17CeNS v7q1SeO+sAvCyW9OXSCd1irlutg3WsvDcd85zH14KFwTaUta4ECpQKT+I9EPKisuL22c hRFA== X-Gm-Message-State: AOAM5333kKxu7XAjDU3KXbpKHxQSZAOYhEdC6cMl+3FJ25kC8Z6Wj/0O 0y5srdLWv51BGjmvb0hirM84EQ== X-Google-Smtp-Source: ABdhPJxkXlC7clzgoUJpZjQqzJu5/VxmsYKbYbd3zTtyOhk2pgEWLXuP0pz1Yday8XOx2GUCHmburg== X-Received: by 2002:a2e:87c2:: with SMTP id v2mr16511842ljj.78.1594030049586; Mon, 06 Jul 2020 03:07:29 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id r23sm7736363ljh.76.2020.07.06.03.07.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Jul 2020 03:07:28 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 2B40610220C; Mon, 6 Jul 2020 13:07:29 +0300 (+03) Date: Mon, 6 Jul 2020 13:07:29 +0300 From: "Kirill A. Shutemov" To: Wei Yang Cc: akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, yang.shi@linux.alibaba.com, vbabka@suse.cz, willy@infradead.org, thomas_os@shipmail.org, thellstrom@vmware.com, anshuman.khandual@arm.com, sean.j.christopherson@intel.com, aneesh.kumar@linux.ibm.com, peterx@redhat.com, walken@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, digetx@gmail.com Subject: Re: [RESEND Patch v2 3/4] mm/mremap: calculate extent in one place Message-ID: <20200706100729.y2wbkpc4tyvjojzg@box> References: <20200626135216.24314-1-richard.weiyang@linux.alibaba.com> <20200626135216.24314-4-richard.weiyang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200626135216.24314-4-richard.weiyang@linux.alibaba.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 26, 2020 at 09:52:15PM +0800, Wei Yang wrote: > Page tables is moved on the base of PMD. This requires both source > and destination range should meet the requirement. > > Current code works well since move_huge_pmd() and move_normal_pmd() > would check old_addr and new_addr again. And then return to move_ptes() > if the either of them is not aligned. > > In stead of calculating the extent separately, it is better to calculate > in one place, so we know it is not necessary to try move pmd. By doing > so, the logic seems a little clear. > > Signed-off-by: Wei Yang > Tested-by: Dmitry Osipenko > --- > mm/mremap.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/mremap.c b/mm/mremap.c > index de27b12c8a5a..a30b3e86cc99 100644 > --- a/mm/mremap.c > +++ b/mm/mremap.c > @@ -258,6 +258,9 @@ unsigned long move_page_tables(struct vm_area_struct *vma, > extent = next - old_addr; > if (extent > old_end - old_addr) > extent = old_end - old_addr; > + next = (new_addr + PMD_SIZE) & PMD_MASK; Please use round_up() for both 'next' calculations. > + if (extent > next - new_addr) > + extent = next - new_addr; > old_pmd = get_old_pmd(vma->vm_mm, old_addr); > if (!old_pmd) > continue; > @@ -301,9 +304,6 @@ unsigned long move_page_tables(struct vm_area_struct *vma, > > if (pte_alloc(new_vma->vm_mm, new_pmd)) > break; > - next = (new_addr + PMD_SIZE) & PMD_MASK; > - if (extent > next - new_addr) > - extent = next - new_addr; > move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma, > new_pmd, new_addr, need_rmap_locks); > } > -- > 2.20.1 (Apple Git-117) > -- Kirill A. Shutemov