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t=1789762996; bh=jMNQNlEwmiuLJhmuM/5YUT/yMbKaucQuszeHmhLwONQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=KRO8mE4QI67Tt6rV1s06qXUHa62HU5/c3vJdk5Kvt4K3j0K5o2TVsxOrGu2Yxmaqo 5SShVgxZl+gxU5lWsrFbEoQXw5DEKoQPvT1fgfTvNC8LnIlEm7Kq766oJFDPBoJTe6 3WKxEYUmchY6Yh9SQ9LP8FDiicFYMo1BTf2qKzvJIzXEj61VtOjSgHEm7pm3vcy2rH /T52FJcA77bfDgOtl7fJL+kwn1MUi6qmYOp/enaPBcsamt307qP0I9F+Op+o+Tyh+X nOBD/gsStGGdqZEztyNYLHllBv51Ww8MFz8lHTosZQW1S1UIXX9heNvUTNPSNoueVW nB+hzx5ZKV/+Q== Message-ID: Date: Fri, 18 Sep 2026 22:23:06 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 00/14] mm: thp: always enable mTHP support To: Luiz Capitulino , Usama Arif , linux-kernel@vger.kernel.org, linux-mm@kvack.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com, lance.yang@linux.dev Cc: 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 References: <970c8f34-3cf4-4c6c-931c-b132e3bc6838@redhat.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D5B0D40004 X-Stat-Signature: 4xd4f9f8rb6kfme31bn4knmyusn9qyoh X-HE-Tag: 1789762996-503964 X-HE-Meta: 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 5+Qh/S1f /UuZlA4v+KEr9tBYXjKOlL0BulcL6GqutCGVQwAs+DEDM7ZLgxji5zrVoqoBLrE6ad0ugYfHxVuU1wCnlaDibtRgm/lPqyjDat2V3QpTbaobLbNrE39AyAuH8/hVjdgLFluli+17O94WkjZFCXzL8e4IbucpBgh6tKnemK67/mFUJq6V8sVAIiPhAlBL2N/qRS6p3XsCyLYk8YieKQF5nukpFxnlYhR0BQ5y+/snXeiDWYDPYssJBfZCnMqSkNF+qp9/L Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/18/26 16:01, Luiz Capitulino wrote: > > > On 9/18/26 6:37 AM, Usama Arif wrote: >> >> >> On 18/09/2026 02:45, Luiz Capitulino wrote: >>> Introduction >>> ============ >>> >>> 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. >> >> >> Hi Luiz, >> >> Sorry for asking this so late in the series, but which CPUs lack support for >> PMD sized pages? >> >> Is this series mainly for PowerPC? > > No :) > > The architectures that have conditional PMD page support (ie. discovered > at run-time via has_transparent_hugepage()) are x86, s390, powerpc and > mips. > > For x86 for example, even on 64-bit there are cases where the PSE bit > may not be present (eg. some errata and by hypervisor CPUID masking). > > That being said, the main goal of the series is that > has_transparent_hugepage() is overloaded: it has different semantics on > those architectures and is used to gate all THP support (which is not > the right thing to do for mTHP). Yes, and I hope that we can then follow-up with similar PUD support cleanup to rework some of that CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD magic. -- Cheers, David