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 F0925C282C6 for ; Fri, 28 Feb 2025 16:33:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 850F0280008; Fri, 28 Feb 2025 11:33:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 80063280001; Fri, 28 Feb 2025 11:33:33 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 67A9A280008; Fri, 28 Feb 2025 11:33:33 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 47AAA280001 for ; Fri, 28 Feb 2025 11:33:33 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id CED44C0E70 for ; Fri, 28 Feb 2025 16:33:32 +0000 (UTC) X-FDA: 83169899064.04.42E74CF Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) by imf22.hostedemail.com (Postfix) with ESMTP id 7587CC000E for ; Fri, 28 Feb 2025 16:33:30 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=UHKfPYvy; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=jZHJM9WX; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=kUjLj2yE; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=BWsZIPe2; dmarc=none; spf=pass (imf22.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.130 as permitted sender) smtp.mailfrom=vbabka@suse.cz ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1740760410; 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=0IS6vjXMxdNYG8BaRqyPppOz461lgBo1fMEwL/tw4aU=; b=v32dWJXfks+N0NJIG0XQmZqUIH6c6UvQPnWiS+FCHEnT+qpTDr5X22r4oJqxsx1DMeySRf 4eswyrbOyBPNW05397IfQ1Tf2xRoR+GuaxbYLIQi9VV/xzNMTB0fRsJ87aqsW7PAMnAWKw 7mqjiPuQO+reoeVhua0NL7Amn+HBbw8= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=UHKfPYvy; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=jZHJM9WX; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=kUjLj2yE; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=BWsZIPe2; dmarc=none; spf=pass (imf22.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.130 as permitted sender) smtp.mailfrom=vbabka@suse.cz ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1740760410; a=rsa-sha256; cv=none; b=1s76QqdzezDhJ3ey0nGPGK2EmS79VVb4P7ZO1avJb2vyFX+WnW2OYLWsbpbSm60R1yGV5x XcIlpUfQ4TfnedVavLeOAvcM3hvaRVzt7zxuuSZe2vUIMkFXZziM7QGAk3zCuove6lfyXQ /MNsew1xgiHQ30Z51Jfpk2W4wkymAIo= Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (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-out1.suse.de (Postfix) with ESMTPS id EB7E821179; Fri, 28 Feb 2025 16:33:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1740760409; 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=0IS6vjXMxdNYG8BaRqyPppOz461lgBo1fMEwL/tw4aU=; b=UHKfPYvy+ld3+mMl2VrYVf4gItSVS+JY9A+CRiQ9NBBVXTo4+BIOj4u4N7908jYle36hyC UVLT2JdT28amefVuFQQj1+pr7aSkffJokQEGdDrMrATk+pCraD/2f02AyUsa++oTiVqjHe VKQUJk6gLbqqKYiVkdMyqNae2XPHgYw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1740760409; 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=0IS6vjXMxdNYG8BaRqyPppOz461lgBo1fMEwL/tw4aU=; b=jZHJM9WXilymhV5SnaeWWjxVmJYEEmjJOb92o0r4sFvofykXvcKS4YWXeU36lSOClRK0MO DklwUi6B/ShkmXCA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1740760408; 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=0IS6vjXMxdNYG8BaRqyPppOz461lgBo1fMEwL/tw4aU=; b=kUjLj2yEwXeNlokZ/kQO7kdMVFNwjIus6rd+Oqv9beqeWmCmdafW5JYDbZ5CZZuNbbtGdq imxaX+IY/wMQqxX3K4X3KYAhWaFUL3+icfxLgl+8UpmdrnyS5HqdEV45lHCMLq/rqQbllB RTAC0Bqr9xHZO2Hk31i8YVeCBEw0uJI= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1740760408; 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=0IS6vjXMxdNYG8BaRqyPppOz461lgBo1fMEwL/tw4aU=; b=BWsZIPe2yCSmZaVABvniHNslZhNp+jxoVHgC7y+ozElisImOOynH8rWh8P1KiOo/PvCRIj O6ScXS3cVLeD8lCg== 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 D0519137AC; Fri, 28 Feb 2025 16:33:28 +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 nWxdMljlwWc1YQAAD6G6ig (envelope-from ); Fri, 28 Feb 2025 16:33:28 +0000 Message-ID: Date: Fri, 28 Feb 2025 17:33:28 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/list_lru: make the case where mlru is NULL as unlikely Content-Language: en-US From: Vlastimil Babka To: Shakeel Butt , Jingxiang Zeng Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, chengming.zhou@linux.dev, kasong@tencent.com, kernel test robot References: <20250225153020.2514685-1-jingxiangzeng.cas@gmail.com> 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+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7587CC000E X-Rspam-User: X-Stat-Signature: cchaursiubs17nkax7ga4j5yoaodr6oo X-HE-Tag: 1740760410-963049 X-HE-Meta: U2FsdGVkX199VfCBpLh10sTp/vcDu08H7rVT9UbMdH+eaQAiFerxdvOo3egT1oTywksz6paH5Urn2myX0ZUBqPR4UGjM1p0QN/uwmp9z4ZSdCwHlW3Wu41G9HPViT8ir6Ne6S7QcoRAuzTmWdhyvCF8Dfecr/k1W9GeXFPlYFfolrqzFjnaJthykhqZJHaQNDdopKY2O/7fUbywrf6hT9BI3Jp7D3qDOPhO1nuINGp1t1N5gskOaI9aw0l6rQyn9EZ9qj+7izqDIUJT3x58n3haVeokBbKbq/5oZS0B7cbudF8xVP5o0R2T3MV4ZGXJmjvEPsZEqV1Agxrn9CltA3pzJiHOJs8iMNI6nZiTZCEdNfLoWTYLhtuSnY6bryp3Wz9brKlyvucc4fMNSG7YkdusvH5SLRZRrlKj5LjIfA5Eja+rlx9ximx8Um+j67LYd/5wqyA7ZUEiLiU89BeMJmCl/oFj3HLpal4QCsG55fUymiWxbtEaqOH8YF9hKD6Z/QjL90l92TQtTL4M5BX6Q9yju3N25GTyR/QdNdg0QPOKbPC7onQq/9N4IpsQdkh4c+IGQcfDuP5LicTLGtKCYDknM8hPEHY2ZkocILnSBJUmZnPAbR9SMDojCR/rky4ZiJOQHhpFkKVT1EpCmfDJ09ewLyo/85hPL+IEmFVHbkDPSxEkJtHYWlEJLbHyocvZ9PGpksthEKfg5Ccwn8Uy5lY24I89jJ6jqtTHEm1jV6/CsIuEoe4iS5q8wMcYdM03Cncdlj3BblCV3jIg8ZpgQHKI0gb4SMbv+jLVlxq3RIvs4NbREPkf6807ZKA4ZmytzmmzDtetr/1MCH+kL+xjPM/2VFUJKi2Utjd82OqyKq5xPRyrrns/0sitFKs5qj5N/sYQqqsk5YyvpYmDnx8bzQVswtlJIKdrOMELDm+TU/Bv49p6OpO1p7w0eO6rM3zfmQ7MYDrDSRQmxnjGR+ge orh/t8jh 5moN5ywW0SSOqRxVDI35mIGDzLaCfN3n2ivYWeLrj9MR2Fre009NRRa5nueitzsCZv3QocwlClKyRjsaVzdWBx9UCA6P5tXlKp60kozgxHvMQ+5NUgWUzEdUOxugMpis8R8seO7EIh/ndz+kLzaPFSap9FjJmR++ES116AUYgP0VeP6QTyX4t0hAWks+IHXug7sOVf8q8y6zCY02Mrg9UJKBtnKqOo2d3JFz1fRNaEfws2Y2MAsXJlWAfcTn7nkBHcYxa7eYlRAM3/9p8rEcbaO/QlQlCQjFiGDLUqcesFqLTf+5RUGXLiyrbcR/Cfri1khe4kfkCm6B6YHc= 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 2/28/25 17:30, Vlastimil Babka wrote: > On 2/25/25 17:23, Shakeel Butt wrote: >> On Tue, Feb 25, 2025 at 11:30:20PM +0800, Jingxiang Zeng wrote: >>> mm/list_lru.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/mm/list_lru.c b/mm/list_lru.c >>> index 064d2018e265..e7e13513ff8e 100644 >>> --- a/mm/list_lru.c >>> +++ b/mm/list_lru.c >>> @@ -552,7 +552,7 @@ static int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru) >>> } >>> xas_unlock_irqrestore(&xas, flags); >>> } while (xas_nomem(&xas, GFP_KERNEL)); >>> - if (mlru) >>> + if (unlikely(mlru)) >>> kfree(mlru); >> >> The report is saying not to check at all. So, just remove the check and >> simply call kfree(mlru) as it handles the NULL check efficiently. > > BTW, if it's unlikely to be !NULL then it's not really efficient to call > kfree() unconditionally as it's a function call and those are more expensive > than inline check (especially with spectre mitigations). OTOH making kfree() do the check inline would bloat all callers, and most of them are likely !NULL. We could perhaps have a kfree_unlikely() variant doing an inline "if unlikely(obj) kfree()" if enough places do it.