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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 67815C282DD for ; Thu, 9 Jan 2020 17:09:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2BBAA2067D for ; Thu, 9 Jan 2020 17:09:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="FoVI9D/X" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BBAA2067D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BF1AA8E0007; Thu, 9 Jan 2020 12:09:12 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BA28E8E0005; Thu, 9 Jan 2020 12:09:12 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A90FE8E0007; Thu, 9 Jan 2020 12:09:12 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0091.hostedemail.com [216.40.44.91]) by kanga.kvack.org (Postfix) with ESMTP id 920888E0005 for ; Thu, 9 Jan 2020 12:09:12 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 3C85582499A8 for ; Thu, 9 Jan 2020 17:09:12 +0000 (UTC) X-FDA: 76358731344.07.face90_6d6206750404e X-HE-Tag: face90_6d6206750404e X-Filterd-Recvd-Size: 5172 Received: from userp2130.oracle.com (userp2130.oracle.com [156.151.31.86]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Thu, 9 Jan 2020 17:09:11 +0000 (UTC) Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 009H3ttr071485; Thu, 9 Jan 2020 17:09:08 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-2019-08-05; bh=Jqd3A0VJ03F00hq5untFVsWZtKv8c1MpD2vegw1vZ4s=; b=FoVI9D/XblCc09k3S9ExstYoBXHbRlcUrUQnQWtTZyxcsDV0wjBmChtLe/OnO9rrtAoN lwOoGLcM/8RtQmM4nSi1StzpRiXTeyE5UdqrlcybUSVSCNftIfSGEIgg0r8ORv9fDiEP yXvZZXn7VsMVoBnvFObbY1/cp1bKPANqupKVjlmV6QC3brzTY2GVkqUEdh57mcOPNVO4 K00hB8f5yX/srw9Th3cAfSBkGx1KvvCav7CsN4z30FzZHhmno/jFRdN6uakuIr/kQVUx Pcbecjkf11AunCGdzVTfCvvBI+x66RzLbmWTNylpk9VSg1G0YI9ZwjgqC4oYFm3IMbnG jQ== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2130.oracle.com with ESMTP id 2xaj4ucaax-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 09 Jan 2020 17:09:08 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 009H4CVu183979; Thu, 9 Jan 2020 17:09:07 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3030.oracle.com with ESMTP id 2xdj4r3n09-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 09 Jan 2020 17:09:07 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 009H96Lw011978; Thu, 9 Jan 2020 17:09:06 GMT Received: from [192.168.1.206] (/71.63.128.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 09 Jan 2020 09:09:06 -0800 Subject: Re: [PATCH v2] mm/page_vma_mapped.c: Detect mismatched pfn of hugetlbfs page in pfn_in_hpage() To: Michal Hocko , Li Xinhai Cc: linux-mm@kvack.org, "Kirill A. Shutemov" References: <1578579963-6075-1-git-send-email-lixinhai.lxh@gmail.com> <20200109150052.GT4951@dhcp22.suse.cz> From: Mike Kravetz Message-ID: <568a2f44-ad16-f3b5-4691-4e6f6ff21bf1@oracle.com> Date: Thu, 9 Jan 2020 09:09:05 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <20200109150052.GT4951@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9495 signatures=668685 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=8.0.1-1911140001 definitions=main-2001090142 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9495 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001090142 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/9/20 7:00 AM, Michal Hocko wrote: > [Cc Mike who is hugetlb maintainer] > > On Thu 09-01-20 14:26:02, Li Xinhai wrote: >> check_pte is called for hugetlbfs page and comparing pfn in pfn_in_page, >> where pfn is compared in range [hpage_pfn, hpage_pfn+HPAGE_PMD_NR). For >> hugetlbfs page, pfn must equal to hpage_pfn, so catch it as bug if they >> are not equal. > > Why do we need this? Would that help to debug any past bug? I have the same question as Michal. Did you see an issue where such a check could help? There is nothing wrong with the proposed code. However, it would be good to know the reason for adding it. I started looking at all possible code paths where this could apply. However, it would be better if you pointed out the concern that caused you to create the patch. -- Mike Kravetz > >> Signed-off-by: Li Xinhai >> Cc: Kirill A. Shutemov >> --- >> mm/page_vma_mapped.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c >> index eff4b45..713aaed 100644 >> --- a/mm/page_vma_mapped.c >> +++ b/mm/page_vma_mapped.c >> @@ -55,6 +55,7 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw) >> static inline bool pfn_in_hpage(struct page *hpage, unsigned long pfn) >> { >> unsigned long hpage_pfn = page_to_pfn(hpage); >> + VM_BUG_ON_PAGE(PageHuge(hpage) && pfn != hpage_pfn, hpage); >> >> /* THP can be referenced by any subpage */ >> return pfn >= hpage_pfn && pfn - hpage_pfn < hpage_nr_pages(hpage); >> -- >> 1.8.3.1