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[209.85.208.174]) by smtp.gmail.com with ESMTPSA id s9sm773700ljp.34.2021.08.27.12.33.17 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Aug 2021 12:33:17 -0700 (PDT) Received: by mail-lj1-f174.google.com with SMTP id p15so13286384ljn.3 for ; Fri, 27 Aug 2021 12:33:17 -0700 (PDT) X-Received: by 2002:a05:651c:908:: with SMTP id e8mr8956231ljq.507.1630092796791; Fri, 27 Aug 2021 12:33:16 -0700 (PDT) MIME-Version: 1.0 References: <20210827164926.1726765-1-agruenba@redhat.com> <20210827164926.1726765-6-agruenba@redhat.com> In-Reply-To: From: Linus Torvalds Date: Fri, 27 Aug 2021 12:33:00 -0700 X-Gmail-Original-Message-ID: Message-ID: To: Al Viro X-Source-IP: 209.85.208.173 X-ServerName: mail-lj1-f173.google.com X-Proofpoint-SPF-Result: pass X-Proofpoint-SPF-Record: v=spf1 ip4:198.145.29.98/31 ip4:72.55.140.81 include:_spf.google.com include:amazonses.com include:_spf.salesforce.com ~all X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10089 signatures=668682 X-Proofpoint-Spam-Details: rule=tap_notspam policy=tap score=0 phishscore=0 adultscore=0 clxscore=383 malwarescore=0 bulkscore=0 impostorscore=0 mlxlogscore=893 priorityscore=323 mlxscore=0 suspectscore=0 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108270113 domainage_hfrom=5365 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-2108270113 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 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-2108270113 X-Proofpoint-GUID: xeKlLyhDIzNXBAvBtMX9lSBx3kqUAjDp X-Proofpoint-ORIG-GUID: xeKlLyhDIzNXBAvBtMX9lSBx3kqUAjDp 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. Seriously. The current semantics are "check the whole area". THOSE MUST NOT CHANGE. Linus _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel