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 4B28BC25B74 for ; Fri, 24 May 2024 17:16:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D441E6B0083; Fri, 24 May 2024 13:16:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CF4476B0085; Fri, 24 May 2024 13:16:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B948E6B0088; Fri, 24 May 2024 13:16:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 9B0546B0083 for ; Fri, 24 May 2024 13:16:49 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 4A6CC160B0C for ; Fri, 24 May 2024 17:16:49 +0000 (UTC) X-FDA: 82153944138.08.FE2C89F Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.21]) by imf15.hostedemail.com (Postfix) with ESMTP id EDBB3A0011 for ; Fri, 24 May 2024 17:16:45 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=jne95erd; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf15.hostedemail.com: domain of dave.hansen@intel.com designates 198.175.65.21 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=1716571007; 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=rUVJeeIefzFRFkS6aeFQW3ubUp8FZWLcxdlIQYlR6pE=; b=XSr47ogyOQ4tZsVJVS1KNcKWBU3CChL9DPEqwL1dXJdWAT5/ZTvr3A33lG6CZR7Hfgvzt0 s0y2tNj1/o5CNFo0cHZB5Z/dv/rvRvcfXmgkE1xB+ETikdhCbCA/qkcWsnmHmidHw4bvep w4rlpI3wApZ+URz5aEGT977tA5TeD6I= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1716571007; a=rsa-sha256; cv=none; b=QA15eW7+9R5szKBl/84ffEQqfs2HLSn+xEyRRvxCj2zmjW4T4IIrMHY9UF94XffFPJwlWB FUgk1iF8dA8cXdTv2t06A/kpElCGti8ykzGScJqfKmY82z+WAgCIWHTLopTx9EqDW/cs9S 7/R2mLUyNXdixWXwIPNSmBYujlnSgDA= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=jne95erd; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf15.hostedemail.com: domain of dave.hansen@intel.com designates 198.175.65.21 as permitted sender) smtp.mailfrom=dave.hansen@intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1716571007; x=1748107007; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=fgqt50EO1ZSclEoqjtlJo4WQ5WUzjv+CTx8jKXMYmVc=; b=jne95erdpFO8QvsTUKHjfxdtv8ektI7a3xLWdiHLwMU7yJvImfnZ1p1x n1sGf4YGVnKXn+1HvfM0W2zl55k63csO5Qyn87/Tc9b31xkp8msHEeGpK bxoGnjwCclii1uhhM5y9miG6/ir0GwBRNAwk6XWEgR4LRVQT4wVEaxLPW OPebVfN4l8MOfPOxCKtOr/Tx/8Wbx+i99/keS5ic5RUPcTYP2LCDQjCHl 63YNl7rAJDBS/HxglmaMPq0ZddACwLm60S5ZousMhiUg/Y/R+PMvgGvVy 0gGhaJFFRRmUe9OQPTLE4sKnYUZ0U0OpiQQXUE05lasiQAl9At+WtkMTp w==; X-CSE-ConnectionGUID: Y5swHexOSlOz6Y0Bwi4fqA== X-CSE-MsgGUID: k5HYH7P2QV6EbMk42Grc7w== X-IronPort-AV: E=McAfee;i="6600,9927,11082"; a="12898198" X-IronPort-AV: E=Sophos;i="6.08,186,1712646000"; d="scan'208";a="12898198" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa113.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 May 2024 10:16:41 -0700 X-CSE-ConnectionGUID: A2uDE7CXTFqPqgJTWs4a4w== X-CSE-MsgGUID: GUTIiLWcSjWUBMGg8FnWvw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,186,1712646000"; d="scan'208";a="34102877" Received: from mgoodin-mobl2.amr.corp.intel.com (HELO [10.125.110.142]) ([10.125.110.142]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 May 2024 10:16:40 -0700 Message-ID: <982317c0-7faa-45f0-82a1-29978c3c9f4d@intel.com> Date: Fri, 24 May 2024 10:16:39 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 00/12] LUF(Lazy Unmap Flush) reducing tlb numbers over 90% To: Byungchul Park , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: kernel_team@skhynix.com, akpm@linux-foundation.org, ying.huang@intel.com, vernhao@tencent.com, mgorman@techsingularity.net, hughd@google.com, willy@infradead.org, david@redhat.com, peterz@infradead.org, luto@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, rjgolo@gmail.com References: <20240510065206.76078-1-byungchul@sk.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: <20240510065206.76078-1-byungchul@sk.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: uiks7jq8uw8gxhmgdnf4rabu6erwhe4y X-Rspamd-Queue-Id: EDBB3A0011 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1716571005-121528 X-HE-Meta: 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 jwPQWstz KjMIxwt9E+4fW7QXY6iFnPO4O7F5uwRzvBqESVZMBE9wtPQZj5GiBBzaOyi1SEBafYADSpzaq7NeM7ClebV0mHTOKy26xDAr33tQwqaYm/T4oyLqPdhGXXZJQsBIHFJaX6KmFxjnOLEm7zKeu5vBe/P+RyhSlXpjws7kf9clfOmXdtm68PQ1RdzgY0w== 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 5/9/24 23:51, Byungchul Park wrote: > To achieve that: > > 1. For the folios that map only to non-writable tlb entries, prevent > tlb flush during unmapping but perform it just before the folios > actually become used, out of buddy or pcp. Is this just _pure_ unmapping (like MADV_DONTNEED), or does it apply to changing the memory map, like munmap() itself? > 2. When any non-writable ptes change to writable e.g. through fault > handler, give up luf mechanism and perform tlb flush required > right away. > > 3. When a writable mapping is created e.g. through mmap(), give up > luf mechanism and perform tlb flush required right away. Let's say you do this: fd = open("/some/file", O_RDONLY); ptr1 = mmap(-1, size, PROT_READ, ..., fd, ...); foo1 = *ptr1; You now have a read-only PTE pointing to the first page of /some/file. Let's say try_to_unmap() comes along and decides it can_luf_folio(). The page gets pulled out of the page cache and freed, the PTE is zeroed. But the TLB is never flushed. Now, someone does: fd2 = open("/some/other/file", O_RDONLY); ptr2 = mmap(ptr1, size, PROT_READ, MAP_FIXED, fd, ...); foo2 = *ptr2; and they overwrite the old VMA. Does foo2 have the contents of the new "/some/other/file" or the old "/some/file"? How does the new mmap() know that there was something to flush? BTW, the same thing could happen without a new mmap(). Someone could modify the file in the middle, maybe even from another process. fd = open("/some/file", O_RDONLY); ptr1 = mmap(-1, size, PROT_READ, ..., fd, ...); foo1 = *ptr1; // LUF happens here // "/some/file" changes foo2 = *ptr1; // Does this see the change?