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 D660DD1713C for ; Mon, 21 Oct 2024 21:20:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 665246B009C; Mon, 21 Oct 2024 17:20:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5EE2C6B009D; Mon, 21 Oct 2024 17:20:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 468DF6B009E; Mon, 21 Oct 2024 17:20:35 -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 2555C6B009C for ; Mon, 21 Oct 2024 17:20:35 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 25868A08C4 for ; Mon, 21 Oct 2024 21:20:06 +0000 (UTC) X-FDA: 82698877674.03.048B513 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.11]) by imf04.hostedemail.com (Postfix) with ESMTP id 423374001A for ; Mon, 21 Oct 2024 21:20:12 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=evPxY4yY; spf=pass (imf04.hostedemail.com: domain of dave.hansen@intel.com designates 192.198.163.11 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1729545482; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc: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=dnApuYtC/TCzZFRvbPMYNEMbj/ikUi+9LVK4TrncokU=; b=lR0gnOZHW3okSfshQoGOYoZhbdht75KU2eG/KH1D3jMPT/jeciowrEsUtCE6fV9MAirsNc 2kfARdGD//5r+oqeHdG0Uq+df8fbkKKg4GQ0sOXbbq6+htiDwP39LMuwYU8dG3USOyT7lj GzUGhN599u0gmtmW6Qtzkziz/EUMy4E= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1729545482; a=rsa-sha256; cv=none; b=u9jlbuUPWvwNmrFRJE1ojYbFCGV+qioHyNIZyIr0vYhUTTB6TWp4eF8Rwd7pOzloYWVGNI TfxMk/ynOHmAkD/k+B8paR7N2/TH17GtYxR3lf5USPHMgfOG1zWR4kijEuWMxuSGS54wz8 cSQXV3495LyV6v4Mp0iEP6aMos+TLAk= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=evPxY4yY; spf=pass (imf04.hostedemail.com: domain of dave.hansen@intel.com designates 192.198.163.11 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1729545632; x=1761081632; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=LHTVtcYowlLgAoVKLIDZb6RmOjwqK0zUS3LkMbSwYbc=; b=evPxY4yYPayHAQ43z6C53PSNq9T/nZ6PpEamuDMX5hLY3aXUerk7U936 cFektOs1Fr7SFhYxklaWoYArLuDA4oG+DoMSNOeaMg5Z49GwamNsoQ4HV Aa1V4nyCZ5A2tBjYuu6fI4Z2mA5tqFJ/38nUUOk7XoG0uiEa57uXl9KhV UPrt4802/T/MGVqo/P6jCt4GNgxAR1sPWJ/4nGpb2JnfjGlpzM34V+cWW yfgP16qjBtHWR+/HsgdG2J7K8T5ngJVeYy5DNYec8dkPB/e+iQCiuEfbp J25brTBTRmwuvfQ3CKyqBKswI/+QBBNH0ppYPG/Y08BTyLM0bQkxRB919 A==; X-CSE-ConnectionGUID: qmnjV8h+T3SdWp7iqSz1ng== X-CSE-MsgGUID: HP1rX6d0SEqwZAa5oOjoLQ== X-IronPort-AV: E=McAfee;i="6700,10204,11232"; a="39635766" X-IronPort-AV: E=Sophos;i="6.11,221,1725346800"; d="scan'208";a="39635766" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Oct 2024 14:20:30 -0700 X-CSE-ConnectionGUID: gqXxmTdGSGOPmdDOVR5EqA== X-CSE-MsgGUID: JtMiBLKwRpuq9N1ULPnS0Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,221,1725346800"; d="scan'208";a="79585855" Received: from gargmani-mobl1.amr.corp.intel.com (HELO [10.124.223.237]) ([10.124.223.237]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Oct 2024 14:20:28 -0700 Message-ID: <1cbc4c4a-a353-4625-ad75-fa32359c99b1@intel.com> Date: Mon, 21 Oct 2024 14:20:26 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/5] mm: add PTE_MARKER_GUARD PTE marker To: Lorenzo Stoakes , Vlastimil Babka Cc: Andrew Morton , Suren Baghdasaryan , "Liam R . Howlett" , Matthew Wilcox , "Paul E . McKenney" , Jann Horn , David Hildenbrand , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Muchun Song , Richard Henderson , Ivan Kokshaysky , Matt Turner , Thomas Bogendoerfer , "James E . J . Bottomley" , Helge Deller , Chris Zankel , Max Filippov , Arnd Bergmann , linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-arch@vger.kernel.org, Shuah Khan , Christian Brauner , linux-kselftest@vger.kernel.org, Sidhartha Kumar , Jeff Xu , Christoph Hellwig , linux-api@vger.kernel.org, John Hubbard , Dave Hansen References: <081837b697a98c7fa5832542b20f603d49e0b557.1729440856.git.lorenzo.stoakes@oracle.com> <9c0991db-9bf8-414c-b3b0-446023df2a7a@suse.cz> <69d1e02b-aa15-4712-90f1-6166b551b992@lucifer.local> <5ee11594-c40a-4ef1-a6c2-f1e38da0e9a3@lucifer.local> 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: <5ee11594-c40a-4ef1-a6c2-f1e38da0e9a3@lucifer.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 423374001A X-Stat-Signature: 9nen5ghbd3bmeizji7xwt1obxco9ha1n X-HE-Tag: 1729545612-841812 X-HE-Meta: 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 Yj5zaPZI O1bmpgrHu5xJ4yJunnLaxuiTHIURJzVnQLqJ0uY/9zq1SfLoX91sox3c3Ehr4wBy2rBttiYltGYa3DPfojNAn84vmylE/UlfsvIJxWd3g725pVI3NsAnxP9AbZI37iAhS9zThZzOFMuXwHFE2QMondMyst4hwA0wSq+DIamu2S4dOvRv63p/VRoOiYh1TxmsX56h7Q59i44uny1QRa2ieephUYrxLiAX0OnP8Ky5QB3v2dTTipPZLCbi4VHkgFVXtB0Er 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 10/21/24 14:13, Lorenzo Stoakes wrote: >> Do you think there's enough value int his to warrant digging in? And indeed >> I imagine bits are in short supply for this and would need a strong >> argument to get... so yeah I don't think too worthwhile most likely! >> >> Thanks for the suggestion though! > To put it on list - Dave Hansen commented on IRC that it would be safer to > avoid this for now due to this being an ABI change, and reasonable to > perhaps add it later if required, so that seems a sensible way forward. We added SEGV_PKUERR because we really did expect signal handlers to want to do something new and special, including consuming si_pkey. Old signal handlers would probably be pretty confused. So, yeah, if it's not crystal clear that new signal handler code is needed, than I'd punt on adding a new SEGV_* code for now. BTW, SEGV_* codes are sequentially assigned. It isn't a bitfield and there are no space constraints. We've only used a dozen or so of them and ->si_code is an int.