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[45.249.212.191]) by mx.google.com with ESMTPS id a23si708594otr.230.2019.02.22.05.57.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 22 Feb 2019 05:57:33 -0800 (PST) Received-SPF: pass (google.com: domain of jingxiangfeng@huawei.com designates 45.249.212.191 as permitted sender) client-ip=45.249.212.191; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jingxiangfeng@huawei.com designates 45.249.212.191 as permitted sender) smtp.mailfrom=jingxiangfeng@huawei.com Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 90B873D0B5CE584C8DB7; Fri, 22 Feb 2019 21:57:27 +0800 (CST) Received: from RH5885H-V3.huawei.com (10.90.53.225) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.408.0; Fri, 22 Feb 2019 21:57:17 +0800 From: Jing Xiangfeng To: , , CC: , , , , , , Jing Xiangfeng Subject: [PATCH v3] mm/hugetlb: Fix unsigned overflow in __nr_hugepages_store_common() Date: Fri, 22 Feb 2019 22:01:28 +0800 Message-ID: <1550844088-67888-1-git-send-email-jingxiangfeng@huawei.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.90.53.225] X-CFilter-Loop: Reflected 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: User can change a node specific hugetlb count. i.e. /sys/devices/system/node/node1/hugepages/hugepages-2048kB the calculated value of count is a total number of huge pages. It could be overflow when a user entering a crazy high value. If so, the total number of huge pages could be a small value which is not user expect. We can simply fix it by setting count to ULONG_MAX, then it goes on. This may be more in line with user's intention of allocating as many huge pages as possible. Signed-off-by: Jing Xiangfeng --- mm/hugetlb.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index afef616..18fa7d7 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2423,7 +2423,10 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy, * per node hstate attribute: adjust count to global, * but restrict alloc/free to the specified node. */ + unsigned long old_count = count; count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; + if (count < old_count) + count = ULONG_MAX; init_nodemask_of_node(nodes_allowed, nid); } else nodes_allowed = &node_states[N_MEMORY]; -- 2.7.4