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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 05954C4321D for ; Thu, 23 Aug 2018 12:49:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC99A2154E for ; Thu, 23 Aug 2018 12:49:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BC99A2154E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1731811AbeHWQSc (ORCPT ); Thu, 23 Aug 2018 12:18:32 -0400 Received: from mx2.suse.de ([195.135.220.15]:39022 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728398AbeHWQSc (ORCPT ); Thu, 23 Aug 2018 12:18:32 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 9DC5AAF76; Thu, 23 Aug 2018 12:48:56 +0000 (UTC) Date: Thu, 23 Aug 2018 14:48:55 +0200 From: Michal Hocko To: Mike Kravetz Cc: kbuild test robot , kbuild-all@01.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A . Shutemov" , =?iso-8859-1?B?Suly9G1l?= Glisse , Vlastimil Babka , Naoya Horiguchi , Davidlohr Bueso , Andrew Morton , stable@vger.kernel.org Subject: Re: [PATCH v3 1/2] mm: migration: fix migration of huge PMD shared pages Message-ID: <20180823124855.GI29735@dhcp22.suse.cz> References: <20180821205902.21223-2-mike.kravetz@oracle.com> <201808220831.eM0je51n%fengguang.wu@intel.com> <975b740d-26a6-eb3f-c8ca-1a9995d0d343@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <975b740d-26a6-eb3f-c8ca-1a9995d0d343@oracle.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 21-08-18 18:10:42, Mike Kravetz wrote: [...] OK, after burning myself when trying to be clever here it seems like your proposed solution is indeed simpler. > +bool huge_pmd_sharing_possible(struct vm_area_struct *vma, > + unsigned long *start, unsigned long *end) > +{ > + unsigned long check_addr = *start; > + bool ret = false; > + > + if (!(vma->vm_flags & VM_MAYSHARE)) > + return ret; > + > + for (check_addr = *start; check_addr < *end; check_addr += PUD_SIZE) { > + unsigned long a_start = check_addr & PUD_MASK; > + unsigned long a_end = a_start + PUD_SIZE; I guess this should be rather in HPAGE_SIZE * PTRS_PER_PTE units as huge_pmd_unshare does. -- Michal Hocko SUSE Labs