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 49636EB26E9 for ; Tue, 10 Feb 2026 16:42:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5E9CF6B0005; Tue, 10 Feb 2026 11:42:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 597D16B0089; Tue, 10 Feb 2026 11:42:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 479746B008A; Tue, 10 Feb 2026 11:42:28 -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 3813B6B0005 for ; Tue, 10 Feb 2026 11:42:28 -0500 (EST) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id C62C91405FA for ; Tue, 10 Feb 2026 16:42:27 +0000 (UTC) X-FDA: 84429115134.21.EB631CE Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) by imf07.hostedemail.com (Postfix) with ESMTP id 3662940009 for ; Tue, 10 Feb 2026 16:42:24 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=MmwFjtpI; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=+H8pOSBx; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=MmwFjtpI; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=+H8pOSBx; spf=pass (imf07.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770741745; 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=USoLikAerZRv3MReWwa4j20dP6GBkJFN1kwtKunN8SI=; b=NeREuZ8IG93YIo5iMZ+i+d6PphK09i6j+P2bDp+0iJTE5+Xh8P794E2EzgcYksN2Xg9nlt 96cqWgV5WtjS62kL06+7YzuRKCKMt+7GXBeT0nYbWVU2vRQXQSLr5OcX/+Lb0yedkjcjD0 O2Js5eslBqi9X5ZUVdfz7qlZiyVi774= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=MmwFjtpI; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=+H8pOSBx; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=MmwFjtpI; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=+H8pOSBx; spf=pass (imf07.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770741745; a=rsa-sha256; cv=none; b=YT5F17nVua23Js/DSNtNxIBZ0PcRk5p8pZqiodHIFibLZSkWtxejVqwaGS0/pf9mnku+ci WD0nG+oJgxsfwDFAvfmGCubCjVo7/dtGPxwjLWA8g8DR+8rkmtUsU5Nev+j1ngfCybdp6L nctY3wKRJbmEw0MJ5yzHrM2/1JihuTo= Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 2F86B5BD6B; Tue, 10 Feb 2026 16:42:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1770741743; h=from:from:reply-to: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:autocrypt:autocrypt; bh=USoLikAerZRv3MReWwa4j20dP6GBkJFN1kwtKunN8SI=; b=MmwFjtpIPDEIl2vxov+/gYVl1xz901bss+y63s52uS9ZEiemSCpJyMnWXpj5g9VLNPMgtk ZEs3zirJHjWbzIpNfsXgO9OW/jBFJxXPRZFI+h25xTm6L7pd8BIrd9jtzKZPcNEcqTXjJe 9ZgU4wobjoYtwJTMdvP/4Yu7aF3+DMs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1770741743; h=from:from:reply-to: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:autocrypt:autocrypt; bh=USoLikAerZRv3MReWwa4j20dP6GBkJFN1kwtKunN8SI=; b=+H8pOSBxdHMKysWrhnAQxA76eY15Rl1pmx6/8SmrTh316iQS7Uag/YuGQkpJAbGfT1YW9f 8oCPEBWI8bqyFcAA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1770741743; h=from:from:reply-to: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:autocrypt:autocrypt; bh=USoLikAerZRv3MReWwa4j20dP6GBkJFN1kwtKunN8SI=; b=MmwFjtpIPDEIl2vxov+/gYVl1xz901bss+y63s52uS9ZEiemSCpJyMnWXpj5g9VLNPMgtk ZEs3zirJHjWbzIpNfsXgO9OW/jBFJxXPRZFI+h25xTm6L7pd8BIrd9jtzKZPcNEcqTXjJe 9ZgU4wobjoYtwJTMdvP/4Yu7aF3+DMs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1770741743; h=from:from:reply-to: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:autocrypt:autocrypt; bh=USoLikAerZRv3MReWwa4j20dP6GBkJFN1kwtKunN8SI=; b=+H8pOSBxdHMKysWrhnAQxA76eY15Rl1pmx6/8SmrTh316iQS7Uag/YuGQkpJAbGfT1YW9f 8oCPEBWI8bqyFcAA== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id D9F393EA62; Tue, 10 Feb 2026 16:42:22 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id g5F6M+5fi2k6XQAAD6G6ig (envelope-from ); Tue, 10 Feb 2026 16:42:22 +0000 Message-ID: <3a5ef8c7-3a75-4014-b565-540af09f7d06@suse.cz> Date: Tue, 10 Feb 2026 17:42:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv6 15/17] mm: Remove the branch from compound_head() Content-Language: en-US To: Kiryl Shutsemau , Andrew Morton , Muchun Song , David Hildenbrand , Matthew Wilcox , Usama Arif , Frank van der Linden Cc: Oscar Salvador , Mike Rapoport , Lorenzo Stoakes , Zi Yan , Baoquan He , Michal Hocko , Johannes Weiner , Jonathan Corbet , Huacai Chen , WANG Xuerui , Palmer Dabbelt , Paul Walmsley , Albert Ou , Alexandre Ghiti , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org References: <20260202155634.650837-1-kas@kernel.org> <20260202155634.650837-16-kas@kernel.org> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <20260202155634.650837-16-kas@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 3662940009 X-Stat-Signature: dsbmsnnzwm6ik5u5jntiknrgnf57y4og X-Rspam-User: X-HE-Tag: 1770741744-710272 X-HE-Meta: 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 CY9LkmAH 45OfcAEi4Nah3/P328GXTVl4Lk/6BAEsCE/Gq/urRMrb5JLfpOU0CRBlW4zPxMyFUCSeK+L2iHRklg2/F+eKIksSGo4h3NeILyskCu5nVNkyN1knNfUIX9FgqVd8MlQpJxwuWwAAPHpE/7GSAYaW4DM7XGZwu8AjMswk0y1cTP9MXOgT6qwj80aUT3nqXgPFjb+UIAwiWkZ9DVgtlUovcfHquggKTRNctm9zL/d8W0LZuQ8P44WGyzYRTfWQF908RAICb0K26q20a1lZxg14siHzv45JOH9JQ8mtK60E5RFuDpuCXOYNR8UIKwYH5y9evv9GZKDkFF5DWfLdpHwi+S/tUiXQOuR6CU8WV6YZP04HPbSX6XviSXH1lt5UTW1EVTC4C 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 2/2/26 16:56, Kiryl Shutsemau wrote: > The compound_head() function is a hot path. For example, the zap path > calls it for every leaf page table entry. > > Rewrite the helper function in a branchless manner to eliminate the risk > of CPU branch misprediction. > > Signed-off-by: Kiryl Shutsemau > Reviewed-by: Muchun Song > Reviewed-by: Zi Yan Reviewed-by: Vlastimil Babka