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Tue, 21 Jan 2020 17:41:00 +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 00LHdBwT156402; Tue, 21 Jan 2020 17:40:59 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3030.oracle.com with ESMTP id 2xnsa92x11-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 21 Jan 2020 17:40:59 +0000 Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 00LHewMa006709; Tue, 21 Jan 2020 17:40:58 GMT Received: from [192.168.1.206] (/71.63.128.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 21 Jan 2020 09:40:58 -0800 Subject: Re: [PATCH v9 4/8] hugetlb: disable region_add file_region coalescing From: Mike Kravetz To: Mina Almasry Cc: shuah@kernel.org, rientjes@google.com, shakeelb@google.com, 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, mkoutny@suse.com References: <20191217231615.164161-1-almasrymina@google.com> <20191217231615.164161-4-almasrymina@google.com> <2afb05c1-8d85-a0cf-aad1-041054aad529@oracle.com> Message-ID: <7fb223ea-3e99-550b-d19c-1352de0d296d@oracle.com> Date: Tue, 21 Jan 2020 09:40:56 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <2afb05c1-8d85-a0cf-aad1-041054aad529@oracle.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=9507 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=929 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001210136 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9507 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=974 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001210136 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 1/21/20 9:38 AM, Mike Kravetz wrote: > On 12/17/19 3:16 PM, Mina Almasry wrote: >> A follow up patch in this series adds hugetlb cgroup uncharge info the > > *nit* > A follow up patch in this series adds hugetlb cgroup uncharge info to the > >> file_region entries in resv->regions. The cgroup uncharge info may >> differ for different regions, so they can no longer be coalesced at >> region_add time. So, disable region coalescing in region_add in this >> patch. >> >> Behavior change: >> >> Say a resv_map exists like this [0->1], [2->3], and [5->6]. >> >> Then a region_chg/add call comes in region_chg/add(f=0, t=5). >> >> Old code would generate resv->regions: [0->5], [5->6]. >> New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], >> [5->6]. >> >> Special care needs to be taken to handle the resv->adds_in_progress >> variable correctly. In the past, only 1 region would be added for every >> region_chg and region_add call. But now, each call may add multiple >> regions, so we can no longer increment adds_in_progress by 1 in region_chg, >> or decrement adds_in_progress by 1 after region_add or region_abort. Instead, >> region_chg calls add_reservation_in_range() to count the number of regions >> needed and allocates those, and that info is passed to region_add and >> region_abort to decrement adds_in_progress correctly. >> >> We've also modified the assumption that region_add after region_chg >> never fails. region_chg now pre-allocates at least 1 region for >> region_add. If region_add needs more regions than region_chg has >> allocated for it, then it may fail. >> >> Signed-off-by: Mina Almasry >> Reviewed-by: Mike Kravetz > > Thanks for the updated comments. Still, > Reviewed-by: Mike Kravetz Sorry, that comment was directed at V10 of the patch. -- Mike Kravetz