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Tue, 17 Aug 2021 00:58:33 +0000 Subject: Re: [PATCH RESEND 0/8] hugetlb: add demote/split page functionality To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Hildenbrand , Michal Hocko , Oscar Salvador , Zi Yan , Muchun Song , Naoya Horiguchi , David Rientjes References: <20210816224953.157796-1-mike.kravetz@oracle.com> <20210816162305.b19bfa3f3ba7431a62ff205f@linux-foundation.org> <5dd4e07b-d2cf-63f2-fc0a-9b371b469a44@oracle.com> <20210816173959.950443c7516a2b178e2ec376@linux-foundation.org> From: Mike Kravetz Message-ID: <54fdf347-e12e-0d3e-6c33-8b1b7898876c@oracle.com> Date: Mon, 16 Aug 2021 17:58:31 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 In-Reply-To: <20210816173959.950443c7516a2b178e2ec376@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MWHPR21CA0049.namprd21.prod.outlook.com (2603:10b6:300:db::11) To BY5PR10MB4196.namprd10.prod.outlook.com (2603:10b6:a03:20d::23) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.2.123] (50.38.35.18) by MWHPR21CA0049.namprd21.prod.outlook.com (2603:10b6:300:db::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4457.1 via Frontend Transport; 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Was this tested? I must admit that I did not specifically test this. However, the patch series to make freeing of hugetlb pages IRQ safe added a (per-hstate)mutex that is taken when sysfs files modify the number of huge pages. demote writes take this mutex (patch 1). That synchronizes not only concurrent writes to demote but also concurrent modifications of nr_hugepages. > > Lots of things are to be added to changelogs & documentation, methinks. > OK. Thank you for taking a look at this! -- Mike Kravetz