From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.11]) (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 2F8EB1E0DBF; Mon, 21 Oct 2024 21:20:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729545633; cv=none; b=PyLKWCGB7lNDns0BdPxj+N+KqqI5bcDUlHB0gx7p5EWMdJnmlXtDbteNYJXzalxj0zRZArZmxVX4QneWKPLt+YC4Vs7WkBhnb+pWKCpL/9dhOHQB5RtLePlEkuacy2BCWR/ml4kO1RvUhE3UuKthhI6CPv/ZugeFC2/BEaZErcc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729545633; c=relaxed/simple; bh=LHTVtcYowlLgAoVKLIDZb6RmOjwqK0zUS3LkMbSwYbc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VyG8hC8Leo2981OTnbtLJ4J+7LNiJXK2hUugA5Qn2jzzdv1MuEB8OwQ6eeagqkctz7wNqSH2P+FCQ3cSKGhQ9PUqDJhYQ53mhkO2v1023IXu549tbDzarwC1RnRTeEYs5+xo8jlT5bg8lKnsQof05FJo9MZDgO2tnEl+Ipbu7VM= 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=SJfA4Y5c; arc=none smtp.client-ip=192.198.163.11 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="SJfA4Y5c" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1729545631; x=1761081631; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=LHTVtcYowlLgAoVKLIDZb6RmOjwqK0zUS3LkMbSwYbc=; b=SJfA4Y5cKTEuK4gecfNhzmQIuO1CBjm2d3OHYYCjL1CcSEqNuW5lntvM 3XS/Ltd2SySZeeXu1L4wEpwPSeWD+W2VpU6DyYspcnriyXHPOVB5dWYCJ YgzVNPTzaq8XgKKSDHrQG/Lz5auI+26z5AVF495mlrEdlIgHjpYbCUYxq HWQf8YoiG9B2MQkFSbXFLJF9wbdw5Sq2QItoEdjlkLlqcvIK714jEbC7i NWwwD+x+qCbQiIo/jjCy0pk/gcTgk5vuJe9HmV47Kscj4bDJcPMIo5fME VzsCQEtpUMkdzKPkcs72y4sBoGMY0ryw3ENvNZh49QTndU7ujc87ySAlg w==; X-CSE-ConnectionGUID: 6akhsGfJQvyFnxjpRv7URg== X-CSE-MsgGUID: kesXXfTqR6ilx8iCOSzTxQ== X-IronPort-AV: E=McAfee;i="6700,10204,11232"; a="39635770" X-IronPort-AV: E=Sophos;i="6.11,221,1725346800"; d="scan'208";a="39635770" 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 Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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.