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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A06FC433F5 for ; Wed, 1 Dec 2021 06:22:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232134AbhLAGZw (ORCPT ); Wed, 1 Dec 2021 01:25:52 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:16266 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231871AbhLAGZv (ORCPT ); Wed, 1 Dec 2021 01:25:51 -0500 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 1B15cIAX002218; Wed, 1 Dec 2021 06:22:18 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : in-reply-to : references : date : message-id : mime-version : content-type; s=pp1; bh=60VzF9r60QMTqaKczXpfroOZx9CoVrufBeApKEeEhdE=; b=CL4fIp146CgvqdH99mh25BGxxFOSfJ3fIF1XHFSgOqv1lCoPSjYzJ+/pR0ueh017vi4a hbzfuxpkxjmQK+uEa6Rb40XK+ebbivqHAOuWsJXgXGaNvVnA1/ET67pEu6IyKr5YCXP/ NFVjfyttjd92Vkks8ZihLNhvXQJDi6fURSoWB+HD3vcfv/x0yUWygwtziZQmUN+beNh7 y4sFW41qaTHl8iOrDhgYo7rFvnKnOMjIPFGUNCXjzFQwICqiUFoGHsIyiyluELVhTi88 IzxtFK3doxDsdCeUrxRzMD6szdfcydlzqf6q7O3W8eDUTfuzroM9npqgkfJehK1kkDoD gg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3cp2sprwv1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 01 Dec 2021 06:22:18 +0000 Received: from m0098410.ppops.net (m0098410.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 1B16IRMv007562; Wed, 1 Dec 2021 06:22:17 GMT Received: from ppma01wdc.us.ibm.com (fd.55.37a9.ip4.static.sl-reverse.com [169.55.85.253]) by mx0a-001b2d01.pphosted.com with ESMTP id 3cp2sprwuk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 01 Dec 2021 06:22:17 +0000 Received: from pps.filterd (ppma01wdc.us.ibm.com [127.0.0.1]) by ppma01wdc.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 1B16Ld2T003867; Wed, 1 Dec 2021 06:22:16 GMT Received: from b03cxnp08028.gho.boulder.ibm.com (b03cxnp08028.gho.boulder.ibm.com [9.17.130.20]) by ppma01wdc.us.ibm.com with ESMTP id 3ckcabdegp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 01 Dec 2021 06:22:16 +0000 Received: from b03ledav001.gho.boulder.ibm.com (b03ledav001.gho.boulder.ibm.com [9.17.130.232]) by b03cxnp08028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1B16MFG553936436 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 1 Dec 2021 06:22:15 GMT Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9A7DB6E054; Wed, 1 Dec 2021 06:22:15 +0000 (GMT) Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6C9A16E052; Wed, 1 Dec 2021 06:22:10 +0000 (GMT) Received: from skywalker.linux.ibm.com (unknown [9.43.38.73]) by b03ledav001.gho.boulder.ibm.com (Postfix) with ESMTP; Wed, 1 Dec 2021 06:22:09 +0000 (GMT) X-Mailer: emacs 28.0.50 (via feedmail 11-beta-1 I) From: "Aneesh Kumar K.V" To: Andrew Morton Cc: linux-mm@kvack.org, Ben Widawsky , Dave Hansen , Feng Tang , Michal Hocko , Andrea Arcangeli , Mel Gorman , Mike Kravetz , Randy Dunlap , Vlastimil Babka , Andi Kleen , Dan Williams , Huang Ying , linux-api@vger.kernel.org Subject: Re: [PATCH v5 2/3] mm/mempolicy: add set_mempolicy_home_node syscall In-Reply-To: <20211130190028.6644054bc7142af36ef5c648@linux-foundation.org> References: <20211116064238.727454-1-aneesh.kumar@linux.ibm.com> <20211116064238.727454-3-aneesh.kumar@linux.ibm.com> <20211129140215.11b7cf9f1034a7fe7017768c@linux-foundation.org> <87wnkqaujt.fsf@linux.ibm.com> <20211130190028.6644054bc7142af36ef5c648@linux-foundation.org> Date: Wed, 01 Dec 2021 11:52:08 +0530 Message-ID: <87r1awc0a7.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: UcOHq32OOeGqmNWdexe8uvVDdw-l_AHv X-Proofpoint-GUID: BHEz3vFUC4OE8XTXBNGuBLyD2SuxBoIu X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-30_10,2021-11-28_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 mlxlogscore=999 priorityscore=1501 impostorscore=0 lowpriorityscore=0 adultscore=0 spamscore=0 malwarescore=0 suspectscore=0 bulkscore=0 phishscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112010034 Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org Andrew Morton writes: > On Tue, 30 Nov 2021 14:29:02 +0530 "Aneesh Kumar K.V" wrote: > >> > What's the thinking here? The node can later be offlined and the >> > kernel takes no action to reset home nodes, so why not permit setting a >> > presently-offline node as the home node? Checking here seems rather >> > arbitrary? >> >> The node online check was needed to avoid accessing >> uninitialised pgdat structure. Such an access can result in >> below crash > > Oh. This is unobvious from reading the code. Which calls for a > comment, no? updated @@ -1497,6 +1498,10 @@ SYSCALL_DEFINE4(set_mempolicy_home_node, unsigned long, start, unsigned long, le if (flags != 0) return -EINVAL; + /* + * Check home_node is online to avoid accessing uninitialized + * NODE_DATA. + */ if (home_node >= MAX_NUMNODES || !node_online(home_node)) return -EINVAL;