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Sat, 03 Oct 2026 08:50:03 -0700 (PDT) X-Received: by 2002:a05:690c:f15:b0:8a8:6a39:37e0 with SMTP id 00721157ae682-8ae39c0a963mr28209777b3.42.1791042603359; Sat, 03 Oct 2026 08:50:03 -0700 (PDT) Received: from [192.168.2.110] ([142.172.30.162]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8aeaac82e1bsm5662017b3.34.2026.10.03.08.50.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 03 Oct 2026 08:50:02 -0700 (PDT) Message-ID: Date: Sat, 3 Oct 2026 11:50:01 -0400 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 v8 14/14] mm: thp: always enable mTHP support To: Lance Yang Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com, 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 References: <752f528f0fed5cdc9de12b54260b0495d4e5a6cb.1789695931.git.luizcap@redhat.com> <20261003031301.48957-1-lance.yang@linux.dev> Content-Language: en-US From: Luiz Capitulino In-Reply-To: <20261003031301.48957-1-lance.yang@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/2/26 11:13 PM, Lance Yang wrote: > > 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/ Yes, I changed the code and didn't update the changelog. Fixed now, thanks Lance. > > Cheers, Lance