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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 41EF2EC1109 for ; Mon, 23 Feb 2026 16:35:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A05146B0088; Mon, 23 Feb 2026 11:35:43 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9A5B06B0089; Mon, 23 Feb 2026 11:35:43 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8BF126B008A; Mon, 23 Feb 2026 11:35:43 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 79E1E6B0088 for ; Mon, 23 Feb 2026 11:35:43 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 351D11B557C for ; Mon, 23 Feb 2026 16:35:43 +0000 (UTC) X-FDA: 84476272566.16.1E6EE8A Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) by imf05.hostedemail.com (Postfix) with ESMTP id AD4D9100017 for ; Mon, 23 Feb 2026 16:35:39 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=UMqhh+0f; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf05.hostedemail.com: domain of dave.hansen@intel.com designates 192.198.163.10 as permitted sender) smtp.mailfrom=dave.hansen@intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1771864541; a=rsa-sha256; cv=none; b=xKRQ1pSjEDHLnsYFObn4H7q8laBT2AggePv1nii09ZhlfhDu+gF0o8oZZTMLdLBhuQ9Idd QOYEpJ8UcdcqvI+Wa3DrW+eXCelr9L6IRRokziqN+Dngdu23sR1w5DpIQ1N01jIO5mWljR bFT7X+TP2+fCRsUo0JCh04edUKi220c= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=UMqhh+0f; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf05.hostedemail.com: domain of dave.hansen@intel.com designates 192.198.163.10 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=1771864541; 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=Mc5jA4WHl5Daz5wji0l03kcXGprq4/im3O/9YHdy/t8=; b=HVACPTRGJgRHDmObA2CZm4PIbDishi+94uRrrtr+Ew9CQlFF6S+6bZZfYE36sufX3QEWtu j7zCF3achRKILoI/bydNNLgiroy5Y7broVXOm3QHd60psgGSayCNiSjZ6WD6pEQLtymWGv xkt8pWIS0R1L6n0LnZzgGYKoS4BY2Yw= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1771864539; x=1803400539; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=INgbWi1LfXN0Ez9j66pRQryu6hcLX3HbDIxmBmoNo/A=; b=UMqhh+0f8PxcCZeTsU9TNGRepU9uoBoIrFs5+sTCZnCi7cTPG2fOdBUe UzuTYFW4AnL5C4kbtEWhVTWa3YfgXgSiBSjF3jfMuyCe+R6bAhwL4Q7d4 /ZvX3GompJzgptgEhHMajdmrnOD4rxZVzZZkoInZ9EaZ0EKeT3KHNdueY pwDASOMcF0F2qmZyqczy48foDuS9217A/8aYprePgV1x3kF35Xgk8sxkT IdQdmKZO01f5MELAlbyA9xm7t5YNTw2wRWdNYq5wAY08oF9RcT7tNzwGY A0+ocBcIdyWk8GO3VFQmg19NnT2sm/TOhDbFmQ0y+8jWZeReiXnQe1ty4 A==; X-CSE-ConnectionGUID: 5gLStNhsSA2RGGOqWlKOaA== X-CSE-MsgGUID: Bia2PpRPTY2Il8DL5+VmrQ== X-IronPort-AV: E=McAfee;i="6800,10657,11710"; a="84225326" X-IronPort-AV: E=Sophos;i="6.21,307,1763452800"; d="scan'208";a="84225326" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Feb 2026 08:35:38 -0800 X-CSE-ConnectionGUID: lndfx9ZQRBO9VCQx+Jnnlw== X-CSE-MsgGUID: GAw/SMTaRk2P18vPFA03VQ== X-ExtLoop1: 1 Received: from dnelso2-mobl.amr.corp.intel.com (HELO [10.125.110.205]) ([10.125.110.205]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Feb 2026 08:35:37 -0800 Message-ID: Date: Mon, 23 Feb 2026 08:35:39 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] mm/mmu_gather: replace IPI with synchronize_rcu() when batch allocation fails To: Lance Yang Cc: akpm@linux-foundation.org, aneesh.kumar@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, npiggin@gmail.com, peterz@infradead.org, will@kernel.org, david@kernel.org References: <2a6c4e62-1663-4a98-9adc-406a6a1ebfd3@kernel.org> <20260223125826.28207-1-lance.yang@linux.dev> <1373db93-3977-425f-ad59-5970e7e50b48@linux.dev> 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: <1373db93-3977-425f-ad59-5970e7e50b48@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 9mtn4cyiihycra1qwcakxfnxwn9z9xth X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: AD4D9100017 X-HE-Tag: 1771864539-748795 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 2/23/26 08:29, Lance Yang wrote: > > Note: Use this when code really needs to wait for synchronization, > *not* for freeing memory. Memory freeing should use RCU callbacks > that don't cause latency spikes in this thread. Yeah, but I'd probably mix it in with the other chit chat about non-atomic contexts. I'd also make it something like: Do not use for freeing memory. Use RCU callbacks instead to avoid latency spikes. to make the commands clear.