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Thu, 27 Jun 2019 18:09:21 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x5RI876F020980; Thu, 27 Jun 2019 18:09:21 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserp3030.oracle.com with ESMTP id 2t9acddck4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 27 Jun 2019 18:09:21 +0000 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 x5RI9HMH015017; Thu, 27 Jun 2019 18:09:19 GMT Received: from [192.168.1.222] (/71.63.128.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 27 Jun 2019 11:09:17 -0700 Subject: Re: LTP hugemmap05 test case failure on arm64 with linux-next (next-20190613) From: Mike Kravetz To: Qian Cai , Will Deacon References: <1560461641.5154.19.camel@lca.pw> <20190614102017.GC10659@fuggles.cambridge.arm.com> <1560514539.5154.20.camel@lca.pw> <054b6532-a867-ec7c-0a72-6a58d4b2723e@arm.com> <20190624093507.6m2quduiacuot3ne@willie-the-truck> <1561381129.5154.55.camel@lca.pw> <1561411839.5154.60.camel@lca.pw> Message-ID: <15651f16-8d30-412f-8064-41ff03f3f47d@oracle.com> Date: Thu, 27 Jun 2019 11:09:16 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9301 signatures=668688 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=8.0.1-1810050000 definitions=main-1906270208 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9301 signatures=668688 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=8.0.1-1810050000 definitions=main-1906270208 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190627_111135_102939_5F782752 X-CRM114-Status: GOOD ( 19.83 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-mm@kvack.org, Catalin Marinas , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Anshuman Khandual Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 6/24/19 2:53 PM, Mike Kravetz wrote: > On 6/24/19 2:30 PM, Qian Cai wrote: >> So the problem is that ipcget_public() has held the semaphore "ids->rwsem" for >> too long seems unnecessarily and then goes to sleep sometimes due to direct >> reclaim (other times LTP hugemmap05 [1] has hugetlb_file_setup() returns >> -ENOMEM), > > Thanks for looking into this! I noticed that recent kernels could take a > VERY long time trying to do high order allocations. In my case it was trying > to do dynamic hugetlb page allocations as well [1]. But, IMO this is more > of a general direct reclaim/compation issue than something hugetlb specific. > >> Ideally, it seems only ipc_findkey() and newseg() in this path needs to hold the >> semaphore to protect concurrency access, so it could just be converted to a >> spinlock instead. > > I do not have enough experience with this ipc code to comment on your proposed > change. But, I will look into it. > > [1] https://lkml.org/lkml/2019/4/23/2 I only took a quick look at the ipc code, but there does not appear to be a quick/easy change to make. The issue is that shared memory creation could take a long time. With issue [1] above unresolved, creation of hugetlb backed shared memory segments could take a VERY long time. I do not believe the test failure is arm specific. Most likely, it is just because testing was done on a system with memory size to trigger this issue? My plan is to focus on [1]. When that is resolved, this issue should go away. -- Mike Kravetz _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel