From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 28B1A3845A3 for ; Thu, 16 Apr 2026 08:44:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776329076; cv=none; b=m7AtztmeWYWiuEVVkziU8saWOuZ48qFP2so73ActtrgprGkAMTfffiti3QPBcG96HIO6tFYhmgkmJt7k4bDeJawgqjZwgdO3vIkRpDSK79BVQS1+b6+ECHQnP0/IL3Ozej0NqZQ2PV1W1oghVoNf1qnKdE8Gx+09EvGKuK8m8p0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776329076; c=relaxed/simple; bh=gAKlU6kkC2VhkkvYb8VZH47y5YSTapJVn5LN7FPl5KU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=O6bdLG+XN/7N35knPDi0csh14XuRBfCE2Scb0ieaWRW5lWLbEQ5afuRnTTStPHC9Ule6rfPp0MWbxCcXokCIiiZpR+KAeLRrfKIevOPWpee9CR/JpaKaZrFcWThjRwQhHtC2mm2hRvYap2SkXCFldHHeDgykHUjlNbCtUzvApk0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sgFpq8ip; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sgFpq8ip" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 89696C2BCAF; Thu, 16 Apr 2026 08:44:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776329075; bh=gAKlU6kkC2VhkkvYb8VZH47y5YSTapJVn5LN7FPl5KU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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