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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 4E002C4320A for ; Sat, 28 Aug 2021 22:11:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 307EA60551 for ; Sat, 28 Aug 2021 22:11:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232464AbhH1WMf (ORCPT ); Sat, 28 Aug 2021 18:12:35 -0400 Received: from zeniv-ca.linux.org.uk ([142.44.231.140]:35788 "EHLO zeniv-ca.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230253AbhH1WMe (ORCPT ); Sat, 28 Aug 2021 18:12:34 -0400 Received: from viro by zeniv-ca.linux.org.uk with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mK6Y4-00GtwB-63; Sat, 28 Aug 2021 22:11:36 +0000 Date: Sat, 28 Aug 2021 22:11:36 +0000 From: Al Viro To: Thomas Gleixner Cc: "Luck, Tony" , Linus Torvalds , Andreas Gruenbacher , Christoph Hellwig , "Darrick J. Wong" , Jan Kara , Matthew Wilcox , cluster-devel , linux-fsdevel , Linux Kernel Mailing List , ocfs2-devel@oss.oracle.com, Borislav Petkov , x86@kernel.org Subject: Re: [PATCH v7 05/19] iov_iter: Introduce fault_in_iov_iter_writeable Message-ID: References: <20210827232246.GA1668365@agluck-desk2.amr.corp.intel.com> <87r1edgs2w.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 28, 2021 at 10:04:41PM +0000, Al Viro wrote: > On Sat, Aug 28, 2021 at 11:47:03PM +0200, Thomas Gleixner wrote: > > > /* Try to handle #PF, but anything else is fatal. */ > > if (ret != -EFAULT) > > return -EINVAL; > > > which all end up in user_insn(). user_insn() returns 0 or the negated > > trap number, which results in -EFAULT for #PF, but for #MC the negated > > trap number is -18 i.e. != -EFAULT. IOW, there is no endless loop. > > > > This used to be a problem before commit: > > > > aee8c67a4faa ("x86/fpu: Return proper error codes from user access functions") > > > > and as the changelog says the initial reason for this was #GP going into > > the fault path, but I'm pretty sure that I also discussed the #MC angle with > > Borislav back then. Should have added some more comments there > > obviously. > > ... or at least have that check spelled > > if (ret != -X86_TRAP_PF) > return -EINVAL; > > Unless I'm misreading your explanation, that is... BTW, is #MC triggered on stored to a poisoned cacheline? Existence of CLZERO would seem to argue against that... 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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 344E8C432BE for ; Sat, 28 Aug 2021 22:11:51 +0000 (UTC) Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B286A60551 for ; Sat, 28 Aug 2021 22:11:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B286A60551 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; 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Sat, 28 Aug 2021 15:11:46 -0700 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 17SMBe8a024399 for ; Sat, 28 Aug 2021 22:11:45 GMT Received: from mx0b-00069f01.pphosted.com (mx0b-00069f01.pphosted.com [205.220.177.26]) by userp3020.oracle.com with ESMTP id 3aqsrf7spt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Sat, 28 Aug 2021 22:11:45 +0000 Received: from pps.filterd (m0246578.ppops.net [127.0.0.1]) by mx0b-00069f01.pphosted.com (8.16.1.2/8.16.0.43) with SMTP id 17SDeppL000336 for ; Sat, 28 Aug 2021 22:11:44 GMT Received: from zeniv-ca.linux.org.uk (zeniv-ca.linux.org.uk [142.44.231.140]) by mx0b-00069f01.pphosted.com with ESMTP id 3aqp832sgq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Sat, 28 Aug 2021 22:11:44 +0000 Received: from viro by zeniv-ca.linux.org.uk with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mK6Y4-00GtwB-63; Sat, 28 Aug 2021 22:11:36 +0000 Date: Sat, 28 Aug 2021 22:11:36 +0000 From: Al Viro To: Thomas Gleixner Message-ID: References: <20210827232246.GA1668365@agluck-desk2.amr.corp.intel.com> <87r1edgs2w.ffs@tglx> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Source-IP: 142.44.231.140 X-ServerName: zeniv-ca.linux.org.uk X-Proofpoint-SPF-Result: None X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10090 signatures=668682 X-Proofpoint-Spam-Details: rule=tap_notspam policy=tap score=0 mlxscore=0 malwarescore=0 impostorscore=0 clxscore=333 bulkscore=0 suspectscore=0 adultscore=0 mlxlogscore=945 phishscore=0 spamscore=0 lowpriorityscore=0 priorityscore=248 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108280155 domainage_hfrom=9158 X-Spam: Clean X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10090 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 malwarescore=0 phishscore=0 mlxscore=0 adultscore=0 bulkscore=0 suspectscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108280155 Cc: cluster-devel , "Luck, Tony" , Jan Kara , Andreas Gruenbacher , x86@kernel.org, Linux Kernel Mailing List , Christoph Hellwig , Borislav Petkov , linux-fsdevel , Linus Torvalds , ocfs2-devel@oss.oracle.com Subject: Re: [Ocfs2-devel] [PATCH v7 05/19] iov_iter: Introduce fault_in_iov_iter_writeable X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10090 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 bulkscore=0 spamscore=0 adultscore=0 malwarescore=0 mlxlogscore=999 phishscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108280155 X-Proofpoint-ORIG-GUID: C_DQdk_zCPx2r_bJmPIP0BU-OuBsi6SI X-Proofpoint-GUID: C_DQdk_zCPx2r_bJmPIP0BU-OuBsi6SI On Sat, Aug 28, 2021 at 10:04:41PM +0000, Al Viro wrote: > On Sat, Aug 28, 2021 at 11:47:03PM +0200, Thomas Gleixner wrote: > > > /* Try to handle #PF, but anything else is fatal. */ > > if (ret != -EFAULT) > > return -EINVAL; > > > which all end up in user_insn(). user_insn() returns 0 or the negated > > trap number, which results in -EFAULT for #PF, but for #MC the negated > > trap number is -18 i.e. != -EFAULT. IOW, there is no endless loop. > > > > This used to be a problem before commit: > > > > aee8c67a4faa ("x86/fpu: Return proper error codes from user access functions") > > > > and as the changelog says the initial reason for this was #GP going into > > the fault path, but I'm pretty sure that I also discussed the #MC angle with > > Borislav back then. Should have added some more comments there > > obviously. > > ... or at least have that check spelled > > if (ret != -X86_TRAP_PF) > return -EINVAL; > > Unless I'm misreading your explanation, that is... BTW, is #MC triggered on stored to a poisoned cacheline? Existence of CLZERO would seem to argue against that... _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Date: Sat, 28 Aug 2021 22:11:36 +0000 Subject: [Cluster-devel] [PATCH v7 05/19] iov_iter: Introduce fault_in_iov_iter_writeable In-Reply-To: References: <20210827232246.GA1668365@agluck-desk2.amr.corp.intel.com> <87r1edgs2w.ffs@tglx> Message-ID: List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Sat, Aug 28, 2021 at 10:04:41PM +0000, Al Viro wrote: > On Sat, Aug 28, 2021 at 11:47:03PM +0200, Thomas Gleixner wrote: > > > /* Try to handle #PF, but anything else is fatal. */ > > if (ret != -EFAULT) > > return -EINVAL; > > > which all end up in user_insn(). user_insn() returns 0 or the negated > > trap number, which results in -EFAULT for #PF, but for #MC the negated > > trap number is -18 i.e. != -EFAULT. IOW, there is no endless loop. > > > > This used to be a problem before commit: > > > > aee8c67a4faa ("x86/fpu: Return proper error codes from user access functions") > > > > and as the changelog says the initial reason for this was #GP going into > > the fault path, but I'm pretty sure that I also discussed the #MC angle with > > Borislav back then. Should have added some more comments there > > obviously. > > ... or at least have that check spelled > > if (ret != -X86_TRAP_PF) > return -EINVAL; > > Unless I'm misreading your explanation, that is... BTW, is #MC triggered on stored to a poisoned cacheline? Existence of CLZERO would seem to argue against that...