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Fri, 27 Aug 2021 12:37:37 -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 17RJZeJT119333 for ; Fri, 27 Aug 2021 19:37:37 GMT Received: from mx0b-00069f01.pphosted.com (mx0b-00069f01.pphosted.com [205.220.177.26]) by userp3020.oracle.com with ESMTP id 3akb92p4xx-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Fri, 27 Aug 2021 19:37:36 +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 17RGjQtl018012 for ; Fri, 27 Aug 2021 19:37:35 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 3aq3up1pf2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Fri, 27 Aug 2021 19:37:35 +0000 Received: from viro by zeniv-ca.linux.org.uk with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJhfJ-00GZrY-Mi; Fri, 27 Aug 2021 19:37:25 +0000 Date: Fri, 27 Aug 2021 19:37:25 +0000 From: Al Viro To: Linus Torvalds Message-ID: References: <20210827164926.1726765-1-agruenba@redhat.com> <20210827164926.1726765-6-agruenba@redhat.com> 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=10089 signatures=668682 X-Proofpoint-Spam-Details: rule=tap_notspam policy=tap score=0 mlxscore=0 lowpriorityscore=0 phishscore=0 impostorscore=0 spamscore=0 adultscore=0 bulkscore=0 clxscore=311 suspectscore=0 priorityscore=336 malwarescore=0 mlxlogscore=914 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108270113 domainage_hfrom=9157 X-Spam: Clean X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10089 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 phishscore=0 spamscore=0 bulkscore=0 mlxlogscore=999 malwarescore=0 adultscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108270114 Cc: cluster-devel , Jan Kara , Andreas Gruenbacher , Linux Kernel Mailing List , Christoph Hellwig , linux-fsdevel , 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=10089 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 malwarescore=0 mlxscore=0 bulkscore=0 mlxlogscore=999 suspectscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108270114 X-Proofpoint-ORIG-GUID: oM0uEaeDJ0cvap_Ib9U83CvWvUWihJ-x X-Proofpoint-GUID: oM0uEaeDJ0cvap_Ib9U83CvWvUWihJ-x On Fri, Aug 27, 2021 at 12:33:00PM -0700, Linus Torvalds wrote: > On Fri, Aug 27, 2021 at 12:23 PM Al Viro wrote: > > > > Could you show the cases where "partial copy, so it's OK" behaviour would > > break anything? > > Absolutely. > > For example, i t would cause an infinite loop in > restore_fpregs_from_user() if the "buf" argument is a situation where > the first page is fine, but the next page is not. > > Why? Because __restore_fpregs_from_user() would take a fault, but then > fault_in_pages_readable() (renamed) would succeed, so you'd just do > that "retry" forever and ever. > > Probably there are a number of other places too. That was literally > the *first* place I looked at. OK... Let me dig out the notes from the last time I looked through that area and grep around a bit. Should be about an hour or two. _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel