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b=V04umGEWs1079s0RySfXElGgYq7u0L01Piv/Ll9FUuBkNTe7ru14oQDeU5DCCIUPo f+x4HOb2YQMqzKHd8oFMA/sW/C88DbVa50alSOhF7TvRWcHFG7k5TGGhHfGe2uRe2p R1ifo+skhV+wl3EMmFfKkp1i01b+NQM0gxZxHdUYIlfEUTZhUuqzLi+rcnjt+IIIwl 2/Ka5ruUdGsy/oiCbSQsTnMA8Pryp1Ek6Qi/WtzXg4ZqK8tt5uDemihfKlccNt4Vmy HNj+Jy1tF1VQFWxd5H9bxyrLfrkUGgJQh3edbHXAUe38uJ4A91K4V4ekbcHSofJGms 5EggwqIO6gS7w== Message-ID: <30a75bb5-7edd-42b1-9a94-8ffe017bdb0b@kernel.org> Date: Sun, 21 Dec 2025 10:49:18 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] selftests/mm/charge_reserved_hugetlb: fix hugetlbfs mount size for large hugepages To: Li Wang Cc: akpm@linux-foundation.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mark Brown , Shuah Khan , Waiman Long References: <20251221085810.3163919-1-liwang@redhat.com> <20251221085810.3163919-4-liwang@redhat.com> <970fa015-9ec8-4903-8e2f-f3e847d550d1@kernel.org> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Stat-Signature: majornfgh396qw5rw4itzrpx3wqgr9ka X-Rspam-User: X-Rspamd-Queue-Id: 8D7CFA000E X-HE-Tag: 1766310563-58105 X-HE-Meta: U2FsdGVkX1+W5hAz6G+OeYxj10DpW9/eKOvJIsRxPd+WIKzZb/OYDSDXCaCNg/CaHknu3I20mvme6Aib24QmjZmuxH6FI1gyoqa3nKghXLcKSp1Yp2tO66cjbbkUzOiSzZyjmQ7V9F8a2J++tG325qb/Vw2k4cFKFMGomF5cSgtmRUclDTESQYyihQk+wREsuaXcrzMMeEMYPsQ/oe6b1XVf3NauN0hLLSROFjMGB3Rb1+5/+cYIAbiQ3u5P67/j8fS+XZByeS5qDyt4R0k4Rn0fDV+7bBl+cwELiMaRhgU9aT8lJFxe+87eyp9+l1zh/WLVBrZztp5fZISBGzZzFdcxO2mkscIMLKPoJnSUJVORPwi4BDfcWlgGIZ5oKLovi6J5MAHyEXcy04PXOTLdqFSyOhgv73nnGDz/beFCnJR8n7YhsKTHBaR31Z/PkvLvfP2+kpUPtoC6b6eT8wnmESkXxhrzJ/jTR51u6rYEB0spptn9U/i7sMmFgdNhbRnjLhUu3iQVeDBREXJfap5JEi5dqmDnPkdQ5xog3vvU1j2g1n2J6dMS4mx3uEjGOFzc4fzTtCirHGnrAFZDuv4ojFdHuv3O2BXpFm4qrSLRn5R5gff0weIIJKitq182uEf3zL1vYCwCc23Bp1IR3KnbGx8DOA8Oe0nKoshlSe3D8ZW8NsP04ptfKZc6CL9QUnM052gmrAtb6hRFWhR6yOKjf2pg9xNK6+EpVZMXG8NPAiw1FwPxVxJISHTonnxvRDq86jiaRqWDPO+NEU8a8RaSRmDSVma1rVED5JhbH9jO3CF+A1ObSz+IyY/1ufkcaVpZMeuu2EnelE1cNWO6cfhox69p8uxmH8TWXwjco21gJjZooZJX20en+8t9hLxrgaVLQoJ/9belyUu4DjQyMCPheWkXVtxR4W2CCPcc28UPUhyBpFhUqNHiFHaudnwztGX3XfrNBoVkMjqpoy0gYAh 6pOf93MH WTkTM1oUU833+HRrbaONFwnU3S8tiVDwiY6DParvhrVsMfH/uaIVef9mla6lqW3TNCBhRTovqz3c32sCylw2fD+bGWC15p4QBYemFU5etRVbg1PFtEwKi+OY9QcM8Rh3S1avXWqWaMt/vedmV+YRTEaouamwmGdf0KInHyy5Qn4iVo1i6p49gPrV2kjyD29TvSPCi8ezCpHnjpKiQfj6j0fgtJpXx/+nGja2SllgrXSfri6PmMAfkvgI0gtBUZ0XjKOa9o34EyyjLa3gCkhvglfEbz/yiANvUgtRgSp56uEjiQsM1vfHeSJDZ5FPb8d+XYTOndO+tddOztcdtjl+RBPRvAZ+oSBQgZwJt 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: List-Subscribe: List-Unsubscribe: On 12/21/25 10:44, Li Wang wrote: > David Hildenbrand (Red Hat) wrote: >> On 12/21/25 09:58, Li Wang wrote: >>> charge_reserved_hugetlb.sh mounts a hugetlbfs instance at /mnt/huge with >>> a fixed size of 256M. On systems with large base hugepages (e.g. 512MB), >>> this is smaller than a single hugepage, so the hugetlbfs mount ends up >>> with effectively zero capacity (often visible as size=0 in mount output). >>> >>> As a result, write_to_hugetlbfs fails with ENOMEM and the test can hang >>> waiting for progress. >> >> I'm curious, what's the history of using "256MB" in the first place (or >> specifying any size?). > > Seems the script initializes it with "256MB" from: > > commit 29750f71a9b4cfae57cdddfbd8ca287eddca5503 > Author: Mina Almasry > Date: Wed Apr 1 21:11:38 2020 -0700 > > hugetlb_cgroup: add hugetlb_cgroup reservation tests What would happen if we don't specify a size at all? -- Cheers David