From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-52.mta0.migadu.com [91.218.175.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3632F226D18 for ; Sat, 3 Oct 2026 03:13:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790997196; cv=none; b=bTuRUO+dg19HNvDYb00v1t25pmDMGOVwdORBEhG4DMQGENlvxPoVWStanF2You1rMeyk0YHaVNy3MqQ7JzrGJ1UHcG4moCpfkLC9Qmknvwf+2j/rCz8I6Yds4dxhMpJK6u/m9dYMCHuJpmRqjJcRAXSPBfavawZmFJTlH5QrYKM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790997196; c=relaxed/simple; bh=a+kpo4RTI73sNREzPUOPFUKRo2xgeedGd8FmVAtqOtU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=NQp5TW+7iyC7vhTp5xNOlCF6X9u3+oIFFDWHSAYgrQ4sw8ApOIhiF9acRM3RjXsEacnEDE4GlXyhM6C12iuzASd7QPk94SGteqMr+vlVNHZREi5BMo5N2/i2+tsOu8wy5Sg3WGOpjiqD83ij097aI/pGc+kTdYL+BI44OEQFK14= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=utDVhz7H; arc=none smtp.client-ip=91.218.175.52 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="utDVhz7H" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=a+kpo4RTI73sNREzPUOPFUKRo2xgeedGd8FmVAtqOtU=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790997190; v=1; x=1791601990; b=utDVhz7HQDhR+GCUlEU9lK3hJjqxejdLvkaeyW4kbux4fgluAchXK5pxhndx2M/BsQGLLDYw kPQnKodGPlHQ1bGV4MIPQTLM7geixm19D/sVCuNlF8qlRxhz2xMWOBrtXVEeuCwGdeaNRfrYH9q a6q84DcnCDm7WLtMbw2QujRQ= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 60bba976d3c550d3; Sat, 03 Oct 2026 03:13:09 +0000 X-Mizu-Trace-ID: 60bba976d3c550d3 X-Migadu-Flow: FLOW_OUT From: Lance Yang To: luizcap@redhat.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com, lance.yang@linux.dev, corbet@lwn.net, tsbogend@alpha.franken.de, maddy@linux.ibm.com, mpe@ellerman.id.au, agordeev@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, x86@kernel.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, hughd@google.com, dave.hansen@linux.intel.com, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, akpm@linux-foundation.org, yintirui@huawei.com, dev.jain@arm.com, usama.arif@linux.dev Subject: Re: [PATCH v8 14/14] mm: thp: always enable mTHP support Date: Sat, 3 Oct 2026 11:13:01 +0800 Message-ID: <20261003031301.48957-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <752f528f0fed5cdc9de12b54260b0495d4e5a6cb.1789695931.git.luizcap@redhat.com> References: <752f528f0fed5cdc9de12b54260b0495d4e5a6cb.1789695931.git.luizcap@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Thu, Sep 17, 2026 at 09:45:35PM -0400, Luiz Capitulino wrote: >If PMD-sized pages are not supported on an architecture (ie. the >arch implements arch_has_pmd_leaves() and it returns false) then the >current code disables all THP, including mTHP. > >This commit fixes this by allowing mTHP to be always enabled for all >archs. When PMD-sized pages are not supported, its sysfs entry won't be >created and their mapping will be disallowed at page-fault time. > >Similarly, this commit implements the following changes for shmem in >shmem_allowable_huge_orders(): > > - Drop the pgtable_has_pmd_leaves() check so that mTHP sizes are > considered > - Filter out PMD and PUD orders from allowable orders when > PMD-sized pages are not supported by the CPU Nit: "and PUD" can go. David mentioned " There is no need to disable PUD-orders, as shmem does not support PUD-orders (unlike DAX). So you can keep it simpler here. " in v4 https://lore.kernel.org/all/ff7bcd65-d444-4da1-890e-75504303ec3f@kernel.org/ Cheers, Lance