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Fri, 20 Nov 2020 04:15:41 -0500 X-MC-Unique: XqBTzF7ZPumVNm0YPi5lsg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 69A038797DA; Fri, 20 Nov 2020 09:15:37 +0000 (UTC) Received: from [10.36.114.78] (ovpn-114-78.ams2.redhat.com [10.36.114.78]) by smtp.corp.redhat.com (Postfix) with ESMTP id 589225D6AD; Fri, 20 Nov 2020 09:15:31 +0000 (UTC) Subject: Re: [PATCH v5 21/21] mm/hugetlb: Disable freeing vmemmap if struct page size is not power of two To: Michal Hocko , Muchun Song Cc: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, osalvador@suse.de, song.bao.hua@hisilicon.com, duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org References: <20201120064325.34492-1-songmuchun@bytedance.com> <20201120064325.34492-22-songmuchun@bytedance.com> <20201120082552.GI3200@dhcp22.suse.cz> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <9b26c749-3bb6-4b16-d1fc-da7ec5d1e8a5@redhat.com> Date: Fri, 20 Nov 2020 10:15:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20201120082552.GI3200@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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 20.11.20 09:25, Michal Hocko wrote: > On Fri 20-11-20 14:43:25, Muchun Song wrote: >> We only can free the unused vmemmap to the buddy system when the >> size of struct page is a power of two. > > Can we actually have !power_of_2 struct pages? AFAIK multiples of 8 bytes (56, 64, 72) are possible. -- Thanks, David / dhildenb