From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (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 974FD288DB; Sat, 7 Jun 2025 14:12:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749305527; cv=none; b=ZhK7LiRoT+BM6bdvwxRkAz/1Q2yJg86bTzoJO5VF5On60IKcu2mt/7ncAaTU0JEeahkL+krb4Uk+0oROmRQczYAIi0WChuWaWMXwVGg/UR4RLwLllhfNoO6ypX2nzN3w/S8Txrpkfhxw5RhVdBWqbTdbmfEswEANYqg0AiGIpVg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749305527; c=relaxed/simple; bh=tOsURfwpu5JIYYGzjKsueBWYxy8LFs6ja4Urw/zMLwY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=N6/VT96qd4sDPvdVJk/kgDHYUM23yI2iyTR7esEJLmaSINR1g9JGoqFVh5P8nCqpQMgh2zyt+7XSmKS2a1zCCceNEXfiy3boO8rczwKimvr/EoW2pSdWb3ZM6a5M2Bri3ULp78+jR9lyL42OHitvYVElUp9MjxpTJsJwVmKZOV8= 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=KpeVND0H; arc=none smtp.client-ip=192.198.163.12 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="KpeVND0H" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1749305526; x=1780841526; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=tOsURfwpu5JIYYGzjKsueBWYxy8LFs6ja4Urw/zMLwY=; b=KpeVND0HpNdRdUWOOYhGagscfYV6c8q4anW6d0ispW3IIV7fRWKSszZ+ DD+5hNl/0L0xnplEKRQ/M407Ax9I6Ljawvc943FCziMJSV6tMzRLCBWTK bPxIHT3RENY0wntHeNgWLYJvW3o//m6Egewr/rCU0BBtB5ajCt7GvpXVp BRG9dzElXeuEToftc3s8UmGFsta38fjRFJwz9hOEU/pCo/BqVassX3tMt +l+GPkndw415gLG2O/ai+pl2371B92beWyy2hLMDI0e/oM1sPWvGIVsD0 a0ASzR4w+GiaDsdt8m/7HEWWB4Qkmu5Rn1YAb7yCSn0SVy84QTwHOhYq6 w==; X-CSE-ConnectionGUID: J46COigUTqKLvFlqxTQSAA== X-CSE-MsgGUID: rO7rDcMkSHiJA61/bGG2Tg== X-IronPort-AV: E=McAfee;i="6800,10657,11457"; a="55231460" X-IronPort-AV: E=Sophos;i="6.16,218,1744095600"; d="scan'208";a="55231460" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2025 07:12:05 -0700 X-CSE-ConnectionGUID: tBMhaICIR3CN1VGkDijZZw== X-CSE-MsgGUID: QIrKOpfMQBC9VEoVh73s9Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,218,1744095600"; d="scan'208";a="169264059" Received: from msatwood-mobl.amr.corp.intel.com (HELO [10.125.111.75]) ([10.125.111.75]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2025 07:12:03 -0700 Message-ID: <34a2bfa5-30e1-4ba0-ac36-bf07a0d60d97@intel.com> Date: Sat, 7 Jun 2025 07:12:02 -0700 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Large modules with 6.15 [was: [PATCH v4 6/6] percpu/x86: Enable strict percpu checks via named AS qualifiers] To: Uros Bizjak Cc: Jiri Slaby , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-bcachefs@vger.kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, Nadav Amit , Dennis Zhou , Tejun Heo , Christoph Lameter , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Linus Torvalds , Andy Lutomirski , Brian Gerst , Peter Zijlstra , Shung-Hsi Yu , Alexei Starovoitov References: <20250127160709.80604-1-ubizjak@gmail.com> <20250127160709.80604-7-ubizjak@gmail.com> <02c00acd-9518-4371-be2c-eb63e5d11d9c@kernel.org> <9767d411-81dc-491b-b6da-419240065ffe@kernel.org> <6412d84a-edc3-4723-89f1-b2017fb0d1ea@intel.com> 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 6/7/25 01:52, Uros Bizjak wrote: > Let me reiterate what the patch brings to the table. It prevents > invalid references of per cpu variables to non-percpu locations. Yes, it's a very useful mechanism. That's exactly why I want to preserve it for developers or things like 0day that do build tests and don't care about modules quadrupling in size. > Hiding these checks behind the CONFIG_EXPERT option breaks the > intention of the patch. IMO, it should be always enabled to avoid > errors, mentioned in the previous paragraph, already during the > development time. I agree, it should always be enabled ... eventually. But now now. That's why we're having this conversation: it's breaking too many things and needs to be disabled. > I'm much more inclined to James' proposal. Maybe we can disable these > checks in v6.15 stable series, but leave them in v6.16? This would > leave a couple of months for distributions to update libbpf. I'd be worried that it will hit a whole bunch of folks doing 6.16 work. I was expecting to revert it _everywhere_ for now, if we go the revert route. James, by partial revert, did you mean to revert in stable but not mainline? I assumed you meant to just revert patch 6/6 of the series (stable and mainline) but leave 1-5 in place so turning it back on later was easier.