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Wed, 3 Apr 2019 16:06:39 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 2rm8f668wq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 03 Apr 2019 16:06:38 +0000 Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x33G6bXr007088; Wed, 3 Apr 2019 16:06:37 GMT Received: from ca-dmjordan1.us.oracle.com (/10.211.9.48) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 03 Apr 2019 09:06:37 -0700 Date: Wed, 3 Apr 2019 12:07:02 -0400 From: Daniel Jordan To: Andrew Morton , Daniel Jordan , Alan Tull , Alexey Kardashevskiy , Alex Williamson , Benjamin Herrenschmidt , Christoph Lameter , Michael Ellerman , Moritz Fischer , Paul Mackerras , Wu Hao , linux-mm@kvack.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/6] mm: change locked_vm's type from unsigned long to atomic64_t Message-ID: <20190403160702.uevv74wajpqtggo7@ca-dmjordan1.us.oracle.com> References: <20190402204158.27582-1-daniel.m.jordan@oracle.com> <20190402204158.27582-2-daniel.m.jordan@oracle.com> <20190402150424.5cf64e19deeafa58fc6c1a9f@linux-foundation.org> <20190402234357.tn3tik4r7k6nbrau@linux-r8p5> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190402234357.tn3tik4r7k6nbrau@linux-r8p5> User-Agent: NeoMutt/20180323-268-5a959c X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9216 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904030109 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9216 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904030109 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 02, 2019 at 04:43:57PM -0700, Davidlohr Bueso wrote: > On Tue, 02 Apr 2019, Andrew Morton wrote: > > > Also, we didn't remove any down_write(mmap_sem)s from core code so I'm > > thinking that the benefit of removing a few mmap_sem-takings from a few > > obscure drivers (sorry ;)) is pretty small. > > afaik porting the remaining incorrect users of locked_vm to pinned_vm was > the next step before this one, which made converting locked_vm to atomic > hardly worth it. Daniel? Right, as you know I tried those incorrect users first, but there were concerns about user-visible changes regarding RLIMIT_MEMLOCK and pinned_vm/locked_vm without the accounting problem between all three being solved. To my knowledge no one has a solution for that, so in the meantime I'm taking the incremental step of getting rid of mmap_sem for locked_vm users. The locked_vm -> pinned_vm conversion can happen later.