From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (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 4997733A719 for ; Thu, 19 Feb 2026 17:30:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.9 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771522240; cv=none; b=Qaz60zTvL/cB6Oa9YZFReFaqGmlFAZlcyIHNP98ez0uyjytLy+X0r0fmU/MzW9uE55yw98n63bOvcdEebpg7f2gLabdDMwqSPyJmvahWQTRqV/1+whQfQ6ehpmLQpWH+2piDl3HNzeL+gz0BpfjyO5T+/ntY+MQdPnPSG/32HhM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771522240; c=relaxed/simple; bh=50rNtqZ65CSurDEZgStPk+RW8GpDeLvz0mbV3n8oyVY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ik6mpVxqVZtfPw8HITXQDHj3MXoc3uyyRXFMltnM746DzC2fkXC7I+wjuSDzs6ZCIz544wjTRLfOC8mLlD/7qHhGZ4uhrXGnSc9hhRGJZoiuVoYJ85ZD8LCE/qWgeWW/XXNmEBkOBJgPQfgAZy8j9dUDHY4Qn36AzZwzeUgrcnQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=OtP+vJu5; arc=none smtp.client-ip=198.175.65.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="OtP+vJu5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1771522238; x=1803058238; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=50rNtqZ65CSurDEZgStPk+RW8GpDeLvz0mbV3n8oyVY=; b=OtP+vJu5Lx4/yktiLSTkaI+f0lWp3E13plzUwXFDlQVhaLrX4dkgkFLj PgQE6xwdSTvGt5QmQsRAXSw0lV6i/WSWz0Mah03/s66oiz/Yzkc3YKWwi bHoLUO9skIiOgXAKPkx9dPS4SPE9XZsBNsbdhyLsKSBXzE1kuYlvLEnbh 8kHZdaInguabLW4pog+u4NH/r7+dGlJPBwf65FPdcRBzvljzOspZl3dEs ibpFj+LtdEj6VKIQ8fdf6tFPxW/UMeljj49YZYR6RC2vuWKzrq8wveCJ0 LAbiBrL3eLKMEtAYSk+dw6UNuY9lPy5GDjQf/JnOzdt/icdFKI0e6wZt8 A==; X-CSE-ConnectionGUID: vxF6uS6JS/CvtsVMM1lbDA== X-CSE-MsgGUID: Rz3HNOX0Rium7/0WiSQAfA== X-IronPort-AV: E=McAfee;i="6800,10657,11706"; a="95236760" X-IronPort-AV: E=Sophos;i="6.21,300,1763452800"; d="scan'208";a="95236760" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Feb 2026 09:30:37 -0800 X-CSE-ConnectionGUID: ZjdLsyqPTlmuBFTxRV9O0Q== X-CSE-MsgGUID: QFi+pnYvTRmwPDu/Inp4aQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,300,1763452800"; d="scan'208";a="214443602" Received: from rchatre-mobl4.amr.corp.intel.com (HELO [10.125.110.10]) ([10.125.110.10]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Feb 2026 09:30:36 -0800 Message-ID: Date: Thu, 19 Feb 2026 09:30:36 -0800 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: [LSF/MM/BPF TOPIC] 64k (or 16k) base page size on x86 To: Kiryl Shutsemau , lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , David Hildenbrand , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Matthew Wilcox , Johannes Weiner , Usama Arif References: From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/19/26 07:08, Kiryl Shutsemau wrote: ... > The patchset is large: > > 378 files changed, 3348 insertions(+), 3102 deletions(-) A few notes about the diffstats: $ git diff v6.17..HEAD arch/x86 | diffstat | tail -1 105 files changed, 874 insertions(+), 843 deletions(-) $ git diff v6.17..HEAD mm | diffstat | tail -1 53 files changed, 1136 insertions(+), 1069 deletions(-) The vast, vast majority of this seems to be the renames. Stuff like: > - new = round_down(new, PAGE_SIZE); > + new = round_down(new, PTE_SIZE); or even less worrying: > -int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid); > +int set_direct_map_valid_noflush(struct page *page, unsigned numpages, bool valid); That stuff obviously needs to be audited but it's far less concerning than the logic changes. So just for review sanity, if you go forward with this, I'd very much appreciate a strong separation of the purely mechanical bits from any logic changes. > On x86, page tables are allocated from the buddy allocator and if PG_SIZE > is greater than 4 KB, we need a way to pack multiple page tables into a > single page. We could use the slab allocator for this, but it would > require relocating the page-table metadata out of struct page. Others mentioned this, but I think this essentially gates what you are doing behind a full tree conversion over to ptdescs. The most useful thing we can do with this series is look at it and decide what _other_ things need to get done before the tree could possibly go in that direction, like ptdesc or a the disambiguation between PTE_SIZE and PG_SIZE that you've kicked off here.