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[70.53.202.134]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8fc2cd04de9sm1152274485a.44.2026.05.04.12.11.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 May 2026 12:11:33 -0700 (PDT) Message-ID: Date: Mon, 4 May 2026 15:11:32 -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 v4 0/9] mm: thp: always enable mTHP support To: Andrew Morton 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, dave.hansen@linux.intel.com, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, lorenzo.stoakes@oracle.com References: <20260503080236.4ea7f3fec0e5788d50113599@linux-foundation.org> Content-Language: en-US, en-CA From: Luiz Capitulino In-Reply-To: <20260503080236.4ea7f3fec0e5788d50113599@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2026-05-03 11:02, Andrew Morton wrote: > On Fri, 1 May 2026 15:18:42 -0400 Luiz Capitulino wrote: > >> Today, if an architecture implements has_transparent_hugepage() and the CPU >> lacks support for PMD-sized pages, the THP code disables all THP, including >> mTHP. In addition, the kernel lacks a well defined API to check for >> PMD-sized page support. It currently relies on has_transparent_hugepage() >> and thp_disabled_by_hw(), but they are not well defined and are tied to >> THP support. >> >> This series addresses both issues by introducing a new well defined API >> to query PMD-sized page support: pgtable_has_pmd_leaves(). Using this >> new helper, we ensure that mTHP remains enabled even when the >> architecture or CPU doesn't support PMD-sized pages. >> >> Thanks to David Hildenbrand for suggesting this improvement and for >> providing guidance (all bugs and misconceptions are mine). >> >> This applies to Linus tree 08d0d3466664 ("Merge tag 'net-7.1-rc2' >> of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net") >> >> NOTE: I used Claude Code Opus 4.6 to *review* the series before >> posting. It did find one issue where a pgtable_has_pmd_leaves() >> check was missing when assining huge_shmem_orders_inherit in >> shmem_init(). > > Thanks. > > Sashiko found a few other things to ask about: > https://sashiko.dev/#/patchset/cover.1777663129.git.luizcap@redhat.com Thanks, I'll go over those soon.