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Fri, 17 Jan 2020 22:58:03 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00HMi0P9072595; Fri, 17 Jan 2020 22:58:03 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3030.oracle.com with ESMTP id 2xjxm9r6tm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 17 Jan 2020 22:58:02 +0000 Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 00HMw1rL030830; Fri, 17 Jan 2020 22:58:01 GMT Received: from [192.168.1.206] (/71.63.128.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 17 Jan 2020 14:58:01 -0800 Subject: Re: [PATCH v10 3/8] hugetlb_cgroup: add reservation accounting for private mappings To: Mina Almasry , rientjes@google.com, shakeelb@google.com Cc: shuah@kernel.org, gthelen@google.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, cgroups@vger.kernel.org, aneesh.kumar@linux.vnet.ibm.com References: <20200115012651.228058-1-almasrymina@google.com> <20200115012651.228058-3-almasrymina@google.com> From: Mike Kravetz Message-ID: <49e5872e-eecb-4279-bc79-bbc1e132ab5d@oracle.com> Date: Fri, 17 Jan 2020 14:57:59 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <20200115012651.228058-3-almasrymina@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9503 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001170175 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9503 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=2 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=8.0.1-1911140001 definitions=main-2001170175 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000013, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/14/20 5:26 PM, Mina Almasry wrote: > Normally the pointer to the cgroup to uncharge hangs off the struct > page, and gets queried when it's time to free the page. With > hugetlb_cgroup reservations, this is not possible. Because it's possible > for a page to be reserved by one task and actually faulted in by another > task. > > The best place to put the hugetlb_cgroup pointer to uncharge for > reservations is in the resv_map. But, because the resv_map has different > semantics for private and shared mappings, the code patch to > charge/uncharge shared and private mappings is different. This patch > implements charging and uncharging for private mappings. > > For private mappings, the counter to uncharge is in > resv_map->reservation_counter. On initializing the resv_map this is set > to NULL. On reservation of a region in private mapping, the tasks > hugetlb_cgroup is charged and the hugetlb_cgroup is placed is > resv_map->reservation_counter. > > On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter. > > Signed-off-by: Mina Almasry Reviewed-by: Mike Kravetz -- Mike Kravetz