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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,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 4F4BCC43444 for ; Thu, 3 Jan 2019 15:05:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2713B20815 for ; Thu, 3 Jan 2019 15:05:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730560AbfACPFZ (ORCPT ); Thu, 3 Jan 2019 10:05:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54234 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726259AbfACPFZ (ORCPT ); Thu, 3 Jan 2019 10:05:25 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9730085363; Thu, 3 Jan 2019 15:05:24 +0000 (UTC) Received: from redhat.com (ovpn-123-124.rdu2.redhat.com [10.10.123.124]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7A3AA5D6A6; Thu, 3 Jan 2019 15:05:23 +0000 (UTC) Date: Thu, 3 Jan 2019 10:05:21 -0500 From: Jerome Glisse To: Matthew Wilcox Cc: Andrew Morton , linux-mm@kvack.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, Christian =?iso-8859-1?Q?K=F6nig?= , Jan Kara Subject: Re: [PATCH] Initialise mmu_notifier_range correctly Message-ID: <20190103150521.GF3395@redhat.com> References: <20190103002126.GM6310@bombadil.infradead.org> <20190103143116.GB3395@redhat.com> <20190103144313.GR6310@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190103144313.GR6310@bombadil.infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 03 Jan 2019 15:05:25 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 03, 2019 at 06:43:13AM -0800, Matthew Wilcox wrote: > On Thu, Jan 03, 2019 at 09:31:16AM -0500, Jerome Glisse wrote: > > On Wed, Jan 02, 2019 at 04:21:26PM -0800, Matthew Wilcox wrote: > > > > > > One of the paths in follow_pte_pmd() initialised the mmu_notifier_range > > > incorrectly. > > > > > > Signed-off-by: Matthew Wilcox > > > Fixes: ac46d4f3c432 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2") > > > Tested-by: Dave Chinner > > > > Actually now that i have read the code again this is not ok to > > do so. The caller of follow_pte_pmd() will call range_init and > > follow pmd will only update the range address. So existing code > > is ok. > > I think you need to re-read your own patch. > > `git show ac46d4f3c43241ffa23d5bf36153a0830c0e02cc` > > @@ -4058,10 +4059,10 @@ static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address, > if (!pmdpp) > goto out; > > - if (start && end) { > - *start = address & PMD_MASK; > - *end = *start + PMD_SIZE; > - mmu_notifier_invalidate_range_start(mm, *start, *end); > + if (range) { > + mmu_notifier_range_init(range, mm, address & PMD_MASK, > + (address & PMD_MASK) + PMD_SIZE); > + mmu_notifier_invalidate_range_start(range); > > ... so it's fine to call range_init() *here*. > > @@ -4069,17 +4070,17 @@ static int __follow_pte_pmd(struct mm_struct *mm, unsign > ed long address, > [...] > if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) > goto out; > > - if (start && end) { > - *start = address & PAGE_MASK; > - *end = *start + PAGE_SIZE; > - mmu_notifier_invalidate_range_start(mm, *start, *end); > + if (range) { > + range->start = address & PAGE_MASK; > + range->end = range->start + PAGE_SIZE; > + mmu_notifier_invalidate_range_start(range); > > ... but then *not* here later in the same function? You're not making > any sense. Ok i see that the patch that add the reason why mmu notifier is call have been drop. So yes using range_init in follow_pte_pmd is fine. With that other patch the reasons is set by the caller of follow_pte_pmd and using range_init would have overwritten it. So this patch is fine for current tree. Sorry i was thinking with the other patch included in mind. Cheers, Jérôme