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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_HIGH,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 A1F63C43144 for ; Tue, 26 Jun 2018 17:00:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50A4126DC3 for ; Tue, 26 Jun 2018 17:00:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="Sua81iqm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 50A4126DC3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.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 S1752437AbeFZRAh (ORCPT ); Tue, 26 Jun 2018 13:00:37 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:35694 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751682AbeFZRAg (ORCPT ); Tue, 26 Jun 2018 13:00:36 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w5QGx3mE189182; Tue, 26 Jun 2018 17:00:19 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2017-10-26; bh=uu13tzXEek56fElJWDdqZooN/giP9fJJ4IS6zVfz/Lo=; b=Sua81iqmQAdR1ZpyN61WR5JqvFHrYX0yxrHYLX6YG1nY6qC5DJw/exHyWtuPEwKHOUL8 yuc7ZdJLAbrRbWB4cbU2Ogh6rlD0PvaMsFmKjTilmDz4MCjEx2X8yLVq53EU7UtLZE1C 9o/O1t5mlGNbqgd1fLChP95j0+QWNalkJi1JA0UCkJY2n8yZEdrPD4lHsUTg9N1q2ruW LAOkvins0fDrfmbbsSCfjOxqyPUsIbJutGj7Rp5VwHeFoNVDankjybCv5doWjmltQn+j cyBh+JQQLfI9VwGLJZFHMI+3TWwJzARgrS/lbDuVDC82bBZiIwBAMx0RaNXcV8V4Xnt3 Ww== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2130.oracle.com with ESMTP id 2jum57sf6v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 26 Jun 2018 17:00:18 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w5QH0HSk008638 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 26 Jun 2018 17:00:18 GMT Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w5QH0G1G028692; Tue, 26 Jun 2018 17:00:17 GMT Received: from [192.168.1.164] (/50.38.38.67) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 26 Jun 2018 10:00:16 -0700 Subject: Re: [PATCH] userfaultfd: hugetlbfs: Fix userfaultfd_huge_must_wait pte access To: Janosch Frank , aarcange@redhat.com Cc: linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, "linux-mm@kvack.org" , Andrew Morton References: <20180626132421.78084-1-frankja@linux.ibm.com> From: Mike Kravetz Message-ID: Date: Tue, 26 Jun 2018 10:00:15 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180626132421.78084-1-frankja@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8936 signatures=668703 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1806260191 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/26/2018 06:24 AM, Janosch Frank wrote: > Use huge_ptep_get to translate huge ptes to normal ptes so we can > check them with the huge_pte_* functions. Otherwise some architectures > will check the wrong values and will not wait for userspace to bring > in the memory. > > Signed-off-by: Janosch Frank > Fixes: 369cd2121be4 ("userfaultfd: hugetlbfs: userfaultfd_huge_must_wait for hugepmd ranges") Adding linux-mm and Andrew on Cc: Thanks for catching and fixing this. I think this needs to be fixed in stable as well. Correct? Assuming userfaultfd is/can be enabled for impacted architectures. Reviewed-by: Mike Kravetz -- Mike Kravetz > --- > fs/userfaultfd.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index 123bf7d516fc..594d192b2331 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -222,24 +222,26 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, > unsigned long reason) > { > struct mm_struct *mm = ctx->mm; > - pte_t *pte; > + pte_t *ptep, pte; > bool ret = true; > > VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); > > - pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma)); > - if (!pte) > + ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma)); > + > + if (!ptep) > goto out; > > ret = false; > + pte = huge_ptep_get(ptep); > > /* > * Lockless access: we're in a wait_event so it's ok if it > * changes under us. > */ > - if (huge_pte_none(*pte)) > + if (huge_pte_none(pte)) > ret = true; > - if (!huge_pte_write(*pte) && (reason & VM_UFFD_WP)) > + if (!huge_pte_write(pte) && (reason & VM_UFFD_WP)) > ret = true; > out: > return ret; >