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[2003:cb:c740:5d00:5143:1cd2:a300:ceff]) by smtp.gmail.com with ESMTPSA id z22-20020a1c4c16000000b003fbb25da65bsm11004831wmf.30.2023.08.07.08.15.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Aug 2023 08:15:55 -0700 (PDT) Message-ID: <5c9ebf69-cd59-0fb3-bb85-1ab219426530@redhat.com> Date: Mon, 7 Aug 2023 17:15:54 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v2 1/4] mm/hugetlb: fix the inconsistency of /proc/sys/vm/nr_huge_pages To: Xueshi Hu , mike.kravetz@oracle.com, muchun.song@linux.dev, corbet@lwn.net, akpm@linux-foundation.org, n-horiguchi@ah.jp.nec.com, osalvador@suse.de Cc: linux-mm@kvack.org References: <20230806074853.317203-1-xueshi.hu@smartx.com> <20230806074853.317203-2-xueshi.hu@smartx.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230806074853.317203-2-xueshi.hu@smartx.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 23F01C0011 X-Stat-Signature: wo1skim7dpjq1wgucdfmatqsuoxdn747 X-HE-Tag: 1691421360-330242 X-HE-Meta: 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 Ydq0wPiF wU4E9pRpTPB1lAShdICHaf4nMI4BPW9WEuBECWMRSO3xDAK/bDzL+nSazUHEF12oL/f1xFTINVf+xbN6GDHdgzj/8tnlJfu56zo5O610+0jTiEyb09mG8/7wep372HIo21nHIXvWOXH1kRFAEF/A+T5Cqnx0N8cXTS9h0JjCRq40Iw02duK/QsT4Zz8ZTUUY2Jr0tNpE/SRmtCK9QLMOSOyJZZu3tTmi1/h8BklWfxvu+eVKl14FALlYECgX9EDUXsji4s0j/08K0TDQZ11hQEnV0tmbhtKoy6BdQDhxKvDDOCVJWdZtaEzRzn+Z+i1qDr799FGhwkAslc481GczHkrYk8Ck+FYPQUyc3wUGmJpTG7ITahRrykyIKS76gBifkxBR735RBU2EAXmUifIQQElMsuTjcCufE7cnnTR3jfZC/b7U= 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 06.08.23 09:48, Xueshi Hu wrote: > There are currently three 'nr_hugepages' used to export the number of huge > pages: > 1. /proc/sys/vm/nr_hugepages > 2. /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages > 3. /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages > > For consistency, all three 'nr_hugepages' should return the total number > of huge pages. When written, the number of persistent huge pages will be > adjusted to the specified value. > > But, /proc/sys/vm/nr_hugepages returns the number of persistent huge > pages. > But that's documented behavior, no? Documentation/admin-guide/mm/hugetlbpage.rst ``/proc/sys/vm/nr_hugepages`` indicates the current number of "persistent" huge pages in the kernel's huge page pool. "Persistent" huge pages will be returned to the huge page pool when freed by a task. A user with root privileges can dynamically allocate more or free some persistent huge pages by increasing or decreasing the value of ``nr_hugepages``. -- Cheers, David / dhildenb