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b=sgFpq8ipNPUDwHg0S0f0GYn797xyHGz9s/2LHOijK/SVj4rkz7LxfyO2I7Z9Ni5hw K1oI08fM+b/5ULka8PZeM0qluz/A5VtfxN04GQfNT95mHES4zZdZa1lpNlbtWMF6S+ ktaitMxWFlz0p3iCAM0ujKfQ9lJdT01SMTlhHhAYgJa29ExGeXHtV97PE9eSosYQiP /MFRQYTwWJIS6fHu2Kefv93+oXlswoLq61TW6kWINDF8BUTTUfxLNH0B5vkGhUUv8p NJ0G95k1La5LxitHuxQnYwT7235OtlfQgy3V7R7bMsSOC6Afz/G6IFEIIeZjK2bLNm yS+27IDNGG4Ew== Message-ID: <82c7ab7a-dc44-47a1-b13d-5119453bc82c@kernel.org> Date: Thu, 16 Apr 2026 10:44:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: shmem: don't set large-order range for internal shmem mount To: Baolin Wang , Zi Yan Cc: willy@infradead.org, akpm@linux-foundation.org, hughd@google.com, ljs@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <2d138a3f-0006-4a01-852a-4570d7ba781d@linux.alibaba.com> <1a3cb6b2-94e0-4268-8cd9-1f9a9deb6c6b@linux.alibaba.com> <875dc63b-0cd2-49e5-8b0d-3fb062789813@kernel.org> <846B17B0-1BAF-4959-8FC2-42744C44B1D6@nvidia.com> <16745f2b-b008-4df1-ac76-f18b4a826dbd@linux.alibaba.com> <4AD72E13-C4AE-4ADA-8AB2-DDB3CEE6A527@nvidia.com> <907b3a20-52b3-4969-8456-bd3a8d2571f2@linux.alibaba.com> <50a01c86-fbf1-4f93-9557-6e5cc1dd1dd7@linux.alibaba.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 6634540008 X-Stat-Signature: aw67ompehhzq7p4nmwhqu5u75rwouqxe X-Rspam-User: X-HE-Tag: 1776329076-151734 X-HE-Meta: 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 tk6R0Z/4 /zvK2enb+hNi96YSBgDYbEjWRZfPxwkg1X1D3R+UzGHLfuPqP9WaNzMFAD8M7+yHMRfS3+dJqf54+4QQNmeeNRbGb7aPJTKdtPJxsPUWWR7jQFhqLlrbK++Gusukl3wssM5FVbYH1sLXlTEuGgxDHHD3SrSojtAUw4CIUydh70IvkiyhaDFsaucN78mVYMz7hUB4iUyv1pYeWZT6YRRlApk5HLrnpfmE1lJthFj9Os48wKTlljqnVSE3RSC78584OO5xtE1qLp/l3XHMoNDgoQt7pyg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/16/26 04:08, Baolin Wang wrote: > > > On 4/16/26 9:52 AM, Zi Yan wrote: >> On 15 Apr 2026, at 21:45, Baolin Wang wrote: >> >>> >>> Personally, I still prefer the current fix (commit 5a90c155defa). We >>> should honor the tmpfs mount option. If it explicitly says no large >>> folios, we shouldn’t call mapping_set_large_folios(). Isn’t that more >>> consistent with its semantics? >> >> Filesystems wishing to turn on large folios in the pagecache should call >> ``mapping_set_large_folios`` when initializing the incore inode. >> >> You mean tmpfs with huge option set is a FS wishing to turn on large >> folios in the pagecache, otherwise it is a FS wishing not to have >> large folio >> in the pagecache. tmpfs with different options is seen as different FSes. > > What I mean is that tmpfs is somewhat different from other filesystems. > We have tried to make tmpfs behave like other FSes, but differences > remain. For example, the previous fix to tmpfs’s large folio allocation > policy, see commit 69e0a3b49003 ("mm: shmem: fix the strategy for the > tmpfs 'huge=' options"). > > So the tmpfs specific 'huge=' mount option is another way it differs > from other filesystems. Personally I'm fine just not calling mapping_set_large_folios() on mappings where there must not ever be large folios. But for every other mapping where there might be large folios at some point, we should just set it. -- Cheers, David