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[141.146.126.79]) by mx.google.com with ESMTPS id x67si2133191itd.31.2019.02.12.16.27.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Feb 2019 16:27:03 -0800 (PST) Received-SPF: pass (google.com: domain of daniel.m.jordan@oracle.com designates 141.146.126.79 as permitted sender) client-ip=141.146.126.79; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=4uhNkb1F; spf=pass (google.com: domain of daniel.m.jordan@oracle.com designates 141.146.126.79 as permitted sender) smtp.mailfrom=daniel.m.jordan@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x1D04ItA127795; Wed, 13 Feb 2019 00:26:36 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=w0tqhPo+t2SUjHi0LS/CYN1wUpJy7dXBRCRCEWoqsoM=; b=4uhNkb1FBNWMTFMQtPUk8damVBnjRIUT7GL5gQsYHz64WDzTPPtvcus+e60ProDyirXA BIBzWsGcRc0nHdUKObIy7isnuU5mxDmG2Eqhgwswz9l/zeQmVrqvv1bmjZ8tNlW73vQ3 tIV/bA4IIkByvi7kHkDTFv1HTComQfdsds3sPIbvf/J7/+e7CJkeuo+0gzdHgxyxhTqs gOh37VPD3tZ18pYTYvOcFEO/9Q8Z+mwAyAeGdutNQ7Rt8uWL2gmrFHP2efApacziCexv WvNERa0JSl/O7luXzRpjaQdoxFvecYasxSh7RwfvLmZctY10vmFVu2Tyzquis+f2PhaC gQ== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2qhre5f4r3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 13 Feb 2019 00:26:36 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x1D0QYY2005778 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 13 Feb 2019 00:26:34 GMT Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x1D0QUic020233; Wed, 13 Feb 2019 00:26:31 GMT Received: from ca-dmjordan1.us.oracle.com (/10.211.9.48) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 12 Feb 2019 16:26:30 -0800 Date: Tue, 12 Feb 2019 19:26:50 -0500 From: Daniel Jordan To: Alex Williamson Cc: Daniel Jordan , Jason Gunthorpe , akpm@linux-foundation.org, dave@stgolabs.net, jack@suse.cz, cl@linux.com, 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, paulus@ozlabs.org, benh@kernel.crashing.org, mpe@ellerman.id.au, hao.wu@intel.com, atull@kernel.org, mdf@kernel.org, aik@ozlabs.ru, peterz@infradead.org Subject: Re: [PATCH 1/5] vfio/type1: use pinned_vm instead of locked_vm to account pinned pages Message-ID: <20190213002650.kav7xc4r2xs5f3ef@ca-dmjordan1.us.oracle.com> References: <20190211224437.25267-1-daniel.m.jordan@oracle.com> <20190211224437.25267-2-daniel.m.jordan@oracle.com> <20190211225620.GO24692@ziepe.ca> <20190211231152.qflff6g2asmkb6hr@ca-dmjordan1.us.oracle.com> <20190212114110.17bc8a14@w520.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190212114110.17bc8a14@w520.home> User-Agent: NeoMutt/20180323-268-5a959c X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9165 signatures=668683 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-1902120162 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Feb 12, 2019 at 11:41:10AM -0700, Alex Williamson wrote: > Daniel Jordan wrote: > > On Mon, Feb 11, 2019 at 03:56:20PM -0700, Jason Gunthorpe wrote: > > > I haven't looked at this super closely, but how does this stuff work? > > > > > > do_mlock doesn't touch pinned_vm, and this doesn't touch locked_vm... > > > > > > Shouldn't all this be 'if (locked_vm + pinned_vm < RLIMIT_MEMLOCK)' ? > > > > > > Otherwise MEMLOCK is really doubled.. > > > > So this has been a problem for some time, but it's not as easy as adding them > > together, see [1][2] for a start. > > > > The locked_vm/pinned_vm issue definitely needs fixing, but all this series is > > trying to do is account to the right counter. Thanks for taking a look, Alex. > This still makes me nervous because we have userspace dependencies on > setting process locked memory. Could you please expand on this? Trying to get more context. > There's a user visible difference if we > account for them in the same bucket vs separate. Perhaps we're > counting in the wrong bucket now, but if we "fix" that and userspace > adapts, how do we ever go back to accounting both mlocked and pinned > memory combined against rlimit? Thanks, PeterZ posted an RFC that addresses this point[1]. It kept pinned_vm and locked_vm accounting separate, but allowed the two to be added safely to be compared against RLIMIT_MEMLOCK. Anyway, until some solution is agreed on, are there objections to converting locked_vm to an atomic, to avoid user-visible changes, instead of switching locked_vm users to pinned_vm? Daniel [1] http://lkml.kernel.org/r/20130524140114.GK23650@twins.programming.kicks-ass.net