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[156.151.31.85]) by mx.google.com with ESMTPS id j133si8656576itj.95.2019.04.03.09.08.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Apr 2019 09:08:46 -0700 (PDT) Received-SPF: pass (google.com: domain of daniel.m.jordan@oracle.com designates 156.151.31.85 as permitted sender) client-ip=156.151.31.85; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=SK873dho; spf=pass (google.com: domain of daniel.m.jordan@oracle.com designates 156.151.31.85 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 (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x33G8eDa108963; Wed, 3 Apr 2019 16:08:40 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 : content-transfer-encoding : in-reply-to; s=corp-2018-07-02; bh=6UKrouLSO9YGf202OeHJTSISbS0nfGS6XGw/sMkz2ko=; b=SK873dhoOJ098oW9qX/LBUJG1yK+EHo0A6lM9ZNxq9LCVL4PhZTJiPZquZgVmVfDhIU6 gfc/VHWuIEJMhw1Q0bpaYcik0fQcG2RHWvuyXg4mvjIVhyQ0MFVRGjRVj2Wvr/fQ1/lW CpJo6iLUkBVC5nhl1AzOmC0zRf7j3pyofsE7DnWNSgcuQOQxL/IyoZFCUMPv4WSAmkgC FpHXzHSyHQfjeB0dA9gV+G9VB4eTpfcmZC3WEu0BVEs3RlYLcfWUee8RbaKrZwckuf07 tC2VlPnvohyw1xBi+C4k/3YJabuJRoHCOtbfXHwbg74phwl2Txu9+DnPkQOhq/hSlQG/ ZA== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2120.oracle.com with ESMTP id 2rj13q9y2k-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 03 Apr 2019 16:08:40 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x33G7ZGm024334; Wed, 3 Apr 2019 16:08:40 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3020.oracle.com with ESMTP id 2rm8f66a6g-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 03 Apr 2019 16:08:40 +0000 Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x33G8cBU017591; Wed, 3 Apr 2019 16:08:38 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 09:08:38 -0700 Date: Wed, 3 Apr 2019 12:09:03 -0400 From: Daniel Jordan To: Christophe Leroy Cc: Daniel Jordan , akpm@linux-foundation.org, Davidlohr Bueso , kvm@vger.kernel.org, Alan Tull , Alexey Kardashevskiy , linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-mm@kvack.org, Alex Williamson , Moritz Fischer , Christoph Lameter , linuxppc-dev@lists.ozlabs.org, Wu Hao Subject: Re: [PATCH 1/6] mm: change locked_vm's type from unsigned long to atomic64_t Message-ID: <20190403160903.5so4okn3ha2tvob3@ca-dmjordan1.us.oracle.com> References: <20190402204158.27582-1-daniel.m.jordan@oracle.com> <20190402204158.27582-2-daniel.m.jordan@oracle.com> <4140911c-8193-010b-e8fc-c8b24ffdf423@c-s.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4140911c-8193-010b-e8fc-c8b24ffdf423@c-s.fr> 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=911 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=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=949 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904030110 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 Wed, Apr 03, 2019 at 06:46:07AM +0200, Christophe Leroy wrote: > > > Le 02/04/2019 à 22:41, Daniel Jordan a écrit : > > Taking and dropping mmap_sem to modify a single counter, locked_vm, is > > overkill when the counter could be synchronized separately. > > > > Make mmap_sem a little less coarse by changing locked_vm to an atomic, > > the 64-bit variety to avoid issues with overflow on 32-bit systems. > > Can you elaborate on the above ? Previously it was 'unsigned long', what > were the issues ? Sure, I responded to this in another thread from this series. > If there was such issues, shouldn't there be a first patch > moving it from unsigned long to u64 before this atomic64_t change ? Or at > least it should be clearly explain here what the issues are and how > switching to a 64 bit counter fixes them. Yes, I can explain the motivation in the next version.