From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5BA25C5475B for ; Mon, 11 Mar 2024 23:34:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E85056B015A; Mon, 11 Mar 2024 19:34:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E35B56B015B; Mon, 11 Mar 2024 19:34:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CD6006B015C; Mon, 11 Mar 2024 19:34:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id BE6586B015A for ; Mon, 11 Mar 2024 19:34:42 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 87900140DEC for ; Mon, 11 Mar 2024 23:34:42 +0000 (UTC) X-FDA: 81886365204.19.33D585C Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) by imf28.hostedemail.com (Postfix) with ESMTP id DE336C0008 for ; Mon, 11 Mar 2024 23:34:38 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=iEU6NIWK; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf28.hostedemail.com: domain of dave.hansen@intel.com designates 198.175.65.15 as permitted sender) smtp.mailfrom=dave.hansen@intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1710200079; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=dmuw5pqHtZmXVWIdnz8yyoQjfCHTM51wkkYce5WCjEo=; b=31nRQahwl/fmjqHWRjh/W+YGiHbdqeDtP56u5jaEijFhN1vhUePz77vtkI1wokptkIq6K1 EcBTbuPoljjakNYeWEYb+W93Elk+lTwBVpPfM/4HXoaLi1JuLXrdtHqy+4cKHUOsVsMXmu OmH1KgqnZOMgRZbxdauKD3pTsFbPKEQ= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=iEU6NIWK; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf28.hostedemail.com: domain of dave.hansen@intel.com designates 198.175.65.15 as permitted sender) smtp.mailfrom=dave.hansen@intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1710200079; a=rsa-sha256; cv=none; b=yWrfajvXF9F567XnbGZtqY2+iM/7ltUKVRir6CDFBXVNS2Co5qENtUOcyWavwljAl+CwzI sfZm3BRwudoS82Lq3L0c0Bw7Ij87vdk1k448FAT2E8DG6kjcfQB0mJ4KEERziQbHW5W9ra UcC09NRsa+fJJC1L1hQEg5iP4ZRyrlQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1710200079; x=1741736079; h=message-id:date:mime-version:subject:to:references:from: in-reply-to:content-transfer-encoding; bh=10qejgMBcinR13l9lIVU4NzpIgEqrpAcOEd3gHCEwfo=; b=iEU6NIWKI40HLOncEAFrQLxHEXLmxFCr4sculLkV+HgGZcMqP6lf5SgQ RO+V71NwPaQ+rEagtY36FClnr8YFVuww8jsTFdadFB+C0bY+Vo5ReCMe+ FyZlmS8pKZVqmNLjJ03+6ALHORb0Z/5a/2ml14BHwHyxwFUZxnxvHuEx3 TfZB3AUeI/PX86DC+xmEL3sQ8CFhibB7an8641/0A9riGFNb80DtxT6jL dLO2QDy0ZOCpIYciYm0r7Xs/aVKYAY3rZFq2CBzdHttgGHcVc4Rf8I4as 3VXsEKs41wayAHZi8klYH/AuPYelmN1pb6G6Rgq8njgVCoy1s+T0FXyhZ Q==; X-IronPort-AV: E=McAfee;i="6600,9927,11010"; a="8707424" X-IronPort-AV: E=Sophos;i="6.07,117,1708416000"; d="scan'208";a="8707424" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2024 16:34:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,117,1708416000"; d="scan'208";a="11919484" Received: from siverson-mobl1.amr.corp.intel.com (HELO [10.209.94.13]) ([10.209.94.13]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2024 16:34:35 -0700 Message-ID: Date: Mon, 11 Mar 2024 16:34:35 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 11/14] x86: add support for Dynamic Kernel Stacks Content-Language: en-US To: Andy Lutomirski , Pasha Tatashin , Linux Kernel Mailing List , linux-mm@kvack.org, Andrew Morton , the arch/x86 maintainers , Borislav Petkov , Christian Brauner , bristot@redhat.com, Ben Segall , Dave Hansen , dianders@chromium.org, dietmar.eggemann@arm.com, eric.devolder@oracle.com, hca@linux.ibm.com, "hch@infradead.org" , "H. Peter Anvin" , Jacob Pan , Jason Gunthorpe , jpoimboe@kernel.org, Joerg Roedel , juri.lelli@redhat.com, Kent Overstreet , kinseyho@google.com, "Kirill A. Shutemov" , lstoakes@gmail.com, mgorman@suse.de, mic@digikod.net, michael.christie@oracle.com, Ingo Molnar , mjguzik@gmail.com, "Michael S. Tsirkin" , Nicholas Piggin , "Peter Zijlstra (Intel)" , Petr Mladek , Rick P Edgecombe , Steven Rostedt , Suren Baghdasaryan , Thomas Gleixner , Uladzislau Rezki , vincent.guittot@linaro.org, vschneid@redhat.com References: <20240311164638.2015063-1-pasha.tatashin@soleen.com> <20240311164638.2015063-12-pasha.tatashin@soleen.com> <3e180c07-53db-4acb-a75c-1a33447d81af@app.fastmail.com> From: Dave Hansen 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: <3e180c07-53db-4acb-a75c-1a33447d81af@app.fastmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: DE336C0008 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: aobiq5qzz4e1amyk941r49kdptgnzge1 X-HE-Tag: 1710200078-453862 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/11/24 15:17, Andy Lutomirski wrote: > I *think* that all x86 implementations won't fill the TLB for a > non-accessed page without also setting the accessed bit, That's my understanding as well. The SDM is a little more obtuse about it: > Whenever the processor uses a paging-structure entry as part of > linear-address translation, it sets the accessed flag in that entry > (if it is not already set). but it's there. But if we start needing Accessed=1 to be accurate, clearing those PTEs gets more expensive because it needs to be atomic to lock out the page walker. It basically needs to start getting treated similarly to what is done for Dirty=1 on userspace PTEs. Not the end of the world, of course, but one more source of overhead.