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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 9EDCBC4360C for ; Mon, 30 Sep 2019 06:30:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 60B8B2075D for ; Mon, 30 Sep 2019 06:30:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 60B8B2075D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=de.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EF26E6B0008; Mon, 30 Sep 2019 02:30:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EA3596B000A; Mon, 30 Sep 2019 02:30:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D44326B000C; Mon, 30 Sep 2019 02:30:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0092.hostedemail.com [216.40.44.92]) by kanga.kvack.org (Postfix) with ESMTP id ACE8D6B0008 for ; Mon, 30 Sep 2019 02:30:35 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 558EA824CA39 for ; Mon, 30 Sep 2019 06:30:35 +0000 (UTC) X-FDA: 75990613230.23.fuel62_5021e4de2343 X-HE-Tag: fuel62_5021e4de2343 X-Filterd-Recvd-Size: 8025 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Mon, 30 Sep 2019 06:30:34 +0000 (UTC) Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x8U6RNQW044302 for ; Mon, 30 Sep 2019 02:30:33 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2va35rpadu-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 30 Sep 2019 02:30:32 -0400 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 30 Sep 2019 07:30:29 +0100 Received: from b06cxnps4074.portsmouth.uk.ibm.com (9.149.109.196) by e06smtp03.uk.ibm.com (192.168.101.133) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 30 Sep 2019 07:30:26 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x8U6UPXS52297924 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 30 Sep 2019 06:30:25 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AB88A11C069; Mon, 30 Sep 2019 06:30:25 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6B8C911C05B; Mon, 30 Sep 2019 06:30:25 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.146]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 30 Sep 2019 06:30:25 +0000 (GMT) Subject: Re: [PATCH] mm/page_alloc: fix a crash in free_pages_prepare() To: Andrew Morton , Qian Cai Cc: heiko.carstens@de.ibm.com, gor@linux.ibm.com, linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1569613623-16820-1-git-send-email-cai@lca.pw> <20190927140222.6f7d0a41b9e734053ee911b9@linux-foundation.org> <1569619686.5576.242.camel@lca.pw> <20190927145945.846a3f3405d3af066827d3f5@linux-foundation.org> From: Christian Borntraeger Openpgp: preference=signencrypt Autocrypt: addr=borntraeger@de.ibm.com; prefer-encrypt=mutual; keydata= mQINBE6cPPgBEAC2VpALY0UJjGmgAmavkL/iAdqul2/F9ONz42K6NrwmT+SI9CylKHIX+fdf J34pLNJDmDVEdeb+brtpwC9JEZOLVE0nb+SR83CsAINJYKG3V1b3Kfs0hydseYKsBYqJTN2j CmUXDYq9J7uOyQQ7TNVoQejmpp5ifR4EzwIFfmYDekxRVZDJygD0wL/EzUr8Je3/j548NLyL 4Uhv6CIPf3TY3/aLVKXdxz/ntbLgMcfZsDoHgDk3lY3r1iwbWwEM2+eYRdSZaR4VD+JRD7p8 0FBadNwWnBce1fmQp3EklodGi5y7TNZ/CKdJ+jRPAAnw7SINhSd7PhJMruDAJaUlbYaIm23A +82g+IGe4z9tRGQ9TAflezVMhT5J3ccu6cpIjjvwDlbxucSmtVi5VtPAMTLmfjYp7VY2Tgr+ T92v7+V96jAfE3Zy2nq52e8RDdUo/F6faxcumdl+aLhhKLXgrozpoe2nL0Nyc2uqFjkjwXXI OBQiaqGeWtxeKJP+O8MIpjyGuHUGzvjNx5S/592TQO3phpT5IFWfMgbu4OreZ9yekDhf7Cvn /fkYsiLDz9W6Clihd/xlpm79+jlhm4E3xBPiQOPCZowmHjx57mXVAypOP2Eu+i2nyQrkapaY IdisDQfWPdNeHNOiPnPS3+GhVlPcqSJAIWnuO7Ofw1ZVOyg/jwARAQABtDRDaHJpc3RpYW4g Qm9ybnRyYWVnZXIgKElCTSkgPGJvcm50cmFlZ2VyQGRlLmlibS5jb20+iQI4BBMBAgAiBQJO nDz4AhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRARe7yAtaYcfOYVD/9sqc6ZdYKD bmDIvc2/1LL0g7OgiA8pHJlYN2WHvIhUoZUIqy8Sw2EFny/nlpPVWfG290JizNS2LZ0mCeGZ 80yt0EpQNR8tLVzLSSr0GgoY0lwsKhAnx3p3AOrA8WXsPL6prLAu3yJI5D0ym4MJ6KlYVIjU ppi4NLWz7ncA2nDwiIqk8PBGxsjdc/W767zOOv7117rwhaGHgrJ2tLxoGWj0uoH3ZVhITP1z gqHXYaehPEELDV36WrSKidTarfThCWW0T3y4bH/mjvqi4ji9emp1/pOWs5/fmd4HpKW+44tD Yt4rSJRSa8lsXnZaEPaeY3nkbWPcy3vX6qafIey5d8dc8Uyaan39WslnJFNEx8cCqJrC77kI vcnl65HaW3y48DezrMDH34t3FsNrSVv5fRQ0mbEed8hbn4jguFAjPt4az1xawSp0YvhzwATJ YmZWRMa3LPx/fAxoolq9cNa0UB3D3jmikWktm+Jnp6aPeQ2Db3C0cDyxcOQY/GASYHY3KNra z8iwS7vULyq1lVhOXg1EeSm+lXQ1Ciz3ub3AhzE4c0ASqRrIHloVHBmh4favY4DEFN19Xw1p 76vBu6QjlsJGjvROW3GRKpLGogQTLslbjCdIYyp3AJq2KkoKxqdeQYm0LZXjtAwtRDbDo71C FxS7i/qfvWJv8ie7bE9A6Wsjn7kCDQROnDz4ARAAmPI1e8xB0k23TsEg8O1sBCTXkV8HSEq7 JlWz7SWyM8oFkJqYAB7E1GTXV5UZcr9iurCMKGSTrSu3ermLja4+k0w71pLxws859V+3z1jr nhB3dGzVZEUhCr3EuN0t8eHSLSMyrlPL5qJ11JelnuhToT6535cLOzeTlECc51bp5Xf6/XSx SMQaIU1nDM31R13o98oRPQnvSqOeljc25aflKnVkSfqWSrZmb4b0bcWUFFUKVPfQ5Z6JEcJg Hp7qPXHW7+tJTgmI1iM/BIkDwQ8qe3Wz8R6rfupde+T70NiId1M9w5rdo0JJsjKAPePKOSDo RX1kseJsTZH88wyJ30WuqEqH9zBxif0WtPQUTjz/YgFbmZ8OkB1i+lrBCVHPdcmvathknAxS bXL7j37VmYNyVoXez11zPYm+7LA2rvzP9WxR8bPhJvHLhKGk2kZESiNFzP/E4r4Wo24GT4eh YrDo7GBHN82V4O9JxWZtjpxBBl8bH9PvGWBmOXky7/bP6h96jFu9ZYzVgIkBP3UYW+Pb1a+b w4A83/5ImPwtBrN324bNUxPPqUWNW0ftiR5b81ms/rOcDC/k/VoN1B+IHkXrcBf742VOLID4 YP+CB9GXrwuF5KyQ5zEPCAjlOqZoq1fX/xGSsumfM7d6/OR8lvUPmqHfAzW3s9n4lZOW5Jfx bbkAEQEAAYkCHwQYAQIACQUCTpw8+AIbDAAKCRARe7yAtaYcfPzbD/9WNGVf60oXezNzSVCL hfS36l/zy4iy9H9rUZFmmmlBufWOATjiGAXnn0rr/Jh6Zy9NHuvpe3tyNYZLjB9pHT6mRZX7 Z1vDxeLgMjTv983TQ2hUSlhRSc6e6kGDJyG1WnGQaqymUllCmeC/p9q5m3IRxQrd0skfdN1V AMttRwvipmnMduy5SdNayY2YbhWLQ2wS3XHJ39a7D7SQz+gUQfXgE3pf3FlwbwZhRtVR3z5u aKjxqjybS3Ojimx4NkWjidwOaUVZTqEecBV+QCzi2oDr9+XtEs0m5YGI4v+Y/kHocNBP0myd pF3OoXvcWdTb5atk+OKcc8t4TviKy1WCNujC+yBSq3OM8gbmk6NwCwqhHQzXCibMlVF9hq5a FiJb8p4QKSVyLhM8EM3HtiFqFJSV7F+h+2W0kDyzBGyE0D8z3T+L3MOj3JJJkfCwbEbTpk4f n8zMboekuNruDw1OADRMPlhoWb+g6exBWx/YN4AY9LbE2KuaScONqph5/HvJDsUldcRN3a5V RGIN40QWFVlZvkKIEkzlzqpAyGaRLhXJPv/6tpoQaCQQoSAc5Z9kM/wEd9e2zMeojcWjUXgg oWj8A/wY4UXExGBu+UCzzP/6sQRpBiPFgmqPTytrDo/gsUGqjOudLiHQcMU+uunULYQxVghC syiRa+UVlsKmx1hsEg== Date: Mon, 30 Sep 2019 08:30:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190927145945.846a3f3405d3af066827d3f5@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 19093006-0012-0000-0000-00000351F1B7 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19093006-0013-0000-0000-0000218C9272 Message-Id: <38b32d77-8ab7-1971-63e4-0bd8c4c1d3da@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-09-30_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=60 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=869 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1909300068 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 27.09.19 23:59, Andrew Morton wrote: > On Fri, 27 Sep 2019 17:28:06 -0400 Qian Cai wrote: >=20 >>> >>> So I think you've moved the arch_free_page() to be after the final >>> thing which can access page contents, yes? If so, we should have a >>> comment in free_pages_prepare() to attmept to prevent this problem fr= om >>> reoccurring as the code evolves? >> >> Right, something like this above arch_free_page() there? >> >> /* >> * It needs to be just above=C2=A0kernel_map_pages(), as s390 could ma= rk those >> * pages unused and then trigger a fault when accessing. >> */ >=20 > I did this. >=20 > --- a/mm/page_alloc.c~mm-page_alloc-fix-a-crash-in-free_pages_prepare-f= ix > +++ a/mm/page_alloc.c > @@ -1179,7 +1179,13 @@ static __always_inline bool free_pages_p > kernel_init_free_pages(page, 1 << order); > =20 > kernel_poison_pages(page, 1 << order, 0); > + /* > + * arch_free_page() can make the page's contents inaccessible. s390 > + * does this. So nothing which can access the page's contents should > + * happen after this. > + */ > arch_free_page(page, order); > + > if (debug_pagealloc_enabled()) > kernel_map_pages(page, 1 << order, 0); With that Acked-by: Christian Borntraeger