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=-8.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 BDA01C433E1 for ; Mon, 17 Aug 2020 14:41:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B14420729 for ; Mon, 17 Aug 2020 14:41:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="Abn2toQF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729026AbgHQOlD (ORCPT ); Mon, 17 Aug 2020 10:41:03 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:26022 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726474AbgHQOlB (ORCPT ); Mon, 17 Aug 2020 10:41:01 -0400 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 07HEYxiW103579; Mon, 17 Aug 2020 10:40:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : cc : subject : message-id : reply-to : references : mime-version : content-type : in-reply-to; s=pp1; bh=eR/szBjZg8h5VQ4Cg6ZXPhbeG0pfH9sw3a+/KivWloY=; b=Abn2toQF/U6FUytnQUsCXm5c5EaOcvjsFs44hDf1rwXZ2CRkMCr/52ZXs2KmnxpxzGiD sT7ITsNzQwDvk5uC4XuzCGf6Z2a84OkT/bhu9ZxYiKhrZ9kFVEil9ZVf4AoSt/W0z6oq XD/HpXqqgETgVHSlaIGK6I9NnGP32FAs2lyeTTR6+bgkAYs1U/7P40vTEM3+LB0TKtCX T7EJ7mUXojyyYfMrltTRwBHJYcTdlaB7HSv840a3euL2r7BXfFUZCNtcR/Oxh9aF6lYN 68IBzBWfRRBRmRP0Ki489fEobFgNRy3cWKHKo1lynSorzMETEfGzNWkzsaqu/lrk+9lz vg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 32y6yw44a6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 17 Aug 2020 10:40:56 -0400 Received: from m0098414.ppops.net (m0098414.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 07HEZsYX107607; Mon, 17 Aug 2020 10:40:55 -0400 Received: from ppma04ams.nl.ibm.com (63.31.33a9.ip4.static.sl-reverse.com [169.51.49.99]) by mx0b-001b2d01.pphosted.com with ESMTP id 32y6yw449c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 17 Aug 2020 10:40:55 -0400 Received: from pps.filterd (ppma04ams.nl.ibm.com [127.0.0.1]) by ppma04ams.nl.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 07HEYZtG031934; Mon, 17 Aug 2020 14:40:53 GMT Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by ppma04ams.nl.ibm.com with ESMTP id 32x7b82c6x-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 17 Aug 2020 14:40:53 +0000 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 07HEepeY25690542 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Aug 2020 14:40:51 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7F4CC52050; Mon, 17 Aug 2020 14:40:51 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by d06av21.portsmouth.uk.ibm.com (Postfix) with SMTP id 1173452054; Mon, 17 Aug 2020 14:40:49 +0000 (GMT) Date: Mon, 17 Aug 2020 20:10:49 +0530 From: Srikar Dronamraju To: Hugh Dickins Cc: Andrew Morton , Song Liu , "Kirill A. Shutemov" , Oleg Nesterov , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] uprobes: __replace_page() avoid BUG in munlock_vma_page() Message-ID: <20200817144049.GD32655@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-17_10:2020-08-17,2020-08-17 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 lowpriorityscore=0 adultscore=0 malwarescore=0 phishscore=0 impostorscore=0 clxscore=1011 bulkscore=0 mlxlogscore=999 mlxscore=0 priorityscore=1501 suspectscore=2 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008170112 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Hugh Dickins [2020-08-16 13:44:25]: > syzbot crashed on the VM_BUG_ON_PAGE(PageTail) in munlock_vma_page(), > when called from uprobes __replace_page(). Which of many ways to fix it? > Settled on not calling when PageCompound (since Head and Tail are equals > in this context, PageCompound the usual check in uprobes.c, and the prior > use of FOLL_SPLIT_PMD will have cleared PageMlocked already). > > Reported-by: syzbot > Fixes: 5a52c9df62b4 ("uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT") > Signed-off-by: Hugh Dickins > Cc: stable@vger.kernel.org # v5.4+ > --- > This one is not a 5.9-rc regression, but still good to fix. > > kernel/events/uprobes.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- v5.9-rc/kernel/events/uprobes.c 2020-08-12 19:46:50.851196584 -0700 > +++ linux/kernel/events/uprobes.c 2020-08-16 13:18:35.292821674 -0700 > @@ -205,7 +205,7 @@ static int __replace_page(struct vm_area > try_to_free_swap(old_page); > page_vma_mapped_walk_done(&pvmw); > > - if (vma->vm_flags & VM_LOCKED) > + if ((vma->vm_flags & VM_LOCKED) && !PageCompound(old_page)) > munlock_vma_page(old_page); > put_page(old_page); > Looks good to me. Reviewed-by: Srikar Dronamraju -- Thanks and Regards Srikar Dronamraju