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 DF5442D837C for ; Wed, 15 Apr 2026 14:36:54 +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=1776263814; cv=none; b=Il2gAtt4Bs2tpMjb6xXtVIzfT7a6wdeKXWC/OQEtaetO5vFjBOG2YRs8sUqGgFa1hIDyJG9G/YaQleuSWD+JFlVJlgMEn/hKY5cFhiN4ev0818zOvj2n1DNsFttniX+dcTqxsWeAOcGJr6w9sVCcN275SG1JEJ1M+U4kfNbTdL0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776263814; c=relaxed/simple; bh=hha2hAkeavqEK37XCQsy4N+tg4I2zcpdNgvkEtX+Ka0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GC2/TH6elSFQ1ge0o4AG2oslbtBNiQRo+DQ0PFsY3q7bZBokq6tcN/V9ehR9y2m2H7QBJhKn266g0gBns8kBqTRJ9G74XpmHEHu9YovoF8PdLPIhRCbo08tvUe3n3oOQ7uvo/PW5Vwna/xj1DOJd40bXdCpbA0MEpbsFCzyOTR4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ajc0ZCrp; 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="ajc0ZCrp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 143D8C19424; Wed, 15 Apr 2026 14:36:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776263814; bh=hha2hAkeavqEK37XCQsy4N+tg4I2zcpdNgvkEtX+Ka0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ajc0ZCrp48qFOd5YeMwU6awPpTlPgOEdgiCW6t9HWpyQfnzlwVgfg/AsqhiG7oyXm nLr+XUl4e20NWvAyngeSQ/T3A9cPeh/iLU2MRydo/sXPwUCq5tStnSMWlbWdk4nxe2 SJC4gavTW9vPFR/OyBPrPy5s+tZ95aIdgN9CMgH8/WkWaJKy/rl5orib3fJXfcnm3N jodgITL9XOiwf+y6glhCkD9qRLxtg1dsbYBzawQcSNn1jKjWe63AYk3tLP1Kn1QIh6 B0XR3httHFjAONX3ZES54kIkzsRSYch53zvV0eJKuxBxnzUiQd02TbR5wDRafb3c9L +LlLcE2o2QiwA== Message-ID: <875dc63b-0cd2-49e5-8b0d-3fb062789813@kernel.org> Date: Wed, 15 Apr 2026 16:36:46 +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 , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, ziy@nvidia.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> 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 4/15/26 12:05, Baolin Wang wrote: > > > On 4/15/26 5:54 PM, David Hildenbrand (Arm) wrote: >>> >>> Yes, that makes sense. >>> >>> However, it’s also possible that the mapping does not support large >>> folios, yet anonymous shmem can still allocate large folios via the >>> sysfs interfaces. That doesn't make sense, right? >> >> That's what I am saying: if there could be large folios in there, then >> let's tell the world. >> >> Getting in a scenario where the mapping claims to not support large >> folios, but then we have large folios in there is inconsistent, not? >> >> [...] >> >>> >>> For the current anonymous shmem (tmpfs is already clear, no questions), >>> I don’t think there will be any "will never have/does never allow" >>> cases, because it can be changed dynamically via the sysfs interfaces. >> >> Right. It's about non-anon shmem with huge=off. >> >>> >>> If we still want that logic, then for anonymous shmem we can treat it as >>> always "might have large folios". > > OK. To resolve the confusion about 1, the logic should be changed as > follows. Does that make sense to you? > > if (sbinfo->huge || (sb->s_flags & SB_KERNMOUNT)) >     mapping_set_large_folios(inode->i_mapping); I think that's better. But has Willy says, maybe we can just unconditionally set it and have it even simpler. -- Cheers, David