From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 2AFFD1B4247 for ; Mon, 16 Jun 2025 15:03:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750086186; cv=none; b=s8szJesvm17d1YIba3Ygzxrl75MMb0tw8UuqCh9YzFWHN9/sRFui7SWOcC4X8xb4ZjnzCDCO6xt8P5yLbS242MzDjheMUMvIhdi38LUHnZzDF2YNGMgfVwWuk4Km4zzJ1N6bceTBPexTu38DR3lZwP9Nu8JBYYN80ro0wu5Y2xs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750086186; c=relaxed/simple; bh=fjNwU6Q+Bp4YVKxpj8EZDgdx84Y3dLXeRzZw9Wd0clw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=V0PxXKhCqpafu3RWElcTEHu2Slg3FonO/KJAWuL+eZooDinTNqSsGcWe5GLKnOU9uU1kzC2BtdMVBEnPOUC6S9Hr4JxTB603nA4lewcHloWFXnF4kiGi1hU70LXiLfmkFf7O3BZn4+7T/TbBhgrqPEpWt9p74AmXEW+h9o5Ig0c= 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=G/pjUeXp; arc=none smtp.client-ip=192.198.163.8 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="G/pjUeXp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1750086185; x=1781622185; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=fjNwU6Q+Bp4YVKxpj8EZDgdx84Y3dLXeRzZw9Wd0clw=; b=G/pjUeXpz7A/7R6Motj8rNyLnYorLLQZlIu/m8lmoZGMZWbuw+CCmk8F xpqL2H6DZ1Du99HsxzzGV9/ja9hqhNygBkHHeZ0YpjUfHus4GmPowbeZ4 WaiTK1RtQv5YeCyE6rRnloXp7s8iW3z0y7qOtcJHDyYVLAAmG2sY1Jo4g ZURxysMsfhnkaIL1HBuJ5nWn1rJ5AFQ07myVMUhKOyCgRSnMnLlR+I3Ey vBe4JAnnlefuFicW5I3nbsgkhoaIEauvF9Ui1mmuKqSUe3R+RfWrE/jXP Hf6/adiEsnzLZwXDQffU+G3R+1i7/BUbjsJeJ7OAwN5o1pIvX0sfVe5tO g==; X-CSE-ConnectionGUID: Yk05THWTQ2+eW/e7fcrYcQ== X-CSE-MsgGUID: wUNPCrKtSG2OWlwayD1CLw== X-IronPort-AV: E=McAfee;i="6800,10657,11465"; a="69810989" X-IronPort-AV: E=Sophos;i="6.16,241,1744095600"; d="scan'208";a="69810989" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jun 2025 08:03:04 -0700 X-CSE-ConnectionGUID: +KKfEZmHQIOePSzV7Vr8rw== X-CSE-MsgGUID: Xcdm950rQNSq6JQocvhP3g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,241,1744095600"; d="scan'208";a="148484950" Received: from msatwood-mobl.amr.corp.intel.com (HELO [10.125.108.25]) ([10.125.108.25]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jun 2025 08:03:04 -0700 Message-ID: Date: Mon, 16 Jun 2025 08:03:03 -0700 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 13/13] x86/folio_zero_user: Add multi-page clearing To: Peter Zijlstra Cc: Ankur Arora , linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, mjguzik@gmail.com, luto@kernel.org, acme@kernel.org, namhyung@kernel.org, tglx@linutronix.de, willy@infradead.org, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com References: <20250616052223.723982-1-ankur.a.arora@oracle.com> <20250616052223.723982-14-ankur.a.arora@oracle.com> <1c0d3994-1397-4bc6-bb55-9c26acdcb477@intel.com> <20250616145007.GF1613376@noisy.programming.kicks-ass.net> 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: <20250616145007.GF1613376@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/16/25 07:50, Peter Zijlstra wrote: > On Mon, Jun 16, 2025 at 07:44:13AM -0700, Dave Hansen wrote: >> To me, that's deserving of an ARCH_HAS_FOO bit that we can set on the >> x86 side that then cajoles the core mm/ code to use the fancy new >> clear_pages_resched() implementation. > Note that we should only set this bit with either full or lazy > preemption selected. Haven't checked the patch-set to see if that > constraint is already taken care of. There is a check in the C code for preempt_model_preemptible(). So as long as there was something like: config SOMETHING_PAGE_CLEARING def_bool y depends on ARCH_HAS_WHATEVER_PAGE_CLEARING depends on !HIGHMEM Then the check for HIGHMEM and the specific architecture support could be along the lines of: static void clear_pages_resched(void *addr, int npages) { int i, remaining; if (!IS_ENABLED(SOMETHING_PAGE_CLEARING) || preempt_model_preemptible()) { clear_pages(addr, npages); goto out; } ... which would also remove the #ifdef CONFIG_HIGHMEM in there now.