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 BC379CCF9E0 for ; Tue, 28 Oct 2025 18:12:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 72FDA801A8; Tue, 28 Oct 2025 14:12:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6E0EB80199; Tue, 28 Oct 2025 14:12:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 61E2B801A8; Tue, 28 Oct 2025 14:12:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 4CC6880199 for ; Tue, 28 Oct 2025 14:12:49 -0400 (EDT) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 148B314052E for ; Tue, 28 Oct 2025 18:12:49 +0000 (UTC) X-FDA: 84048318858.26.CDC8505 Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) by imf06.hostedemail.com (Postfix) with ESMTP id 36900180003 for ; Tue, 28 Oct 2025 18:12:46 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=lQS9HNn2; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf06.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.186 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1761675167; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=/mIcK7vCMiNf076l+LaWZKI497HGob3OxvsLoIs/FEg=; b=iQYEAyRD4NqxuGel9nb4e5p5QFmBmXPKLWdkOnmc3lIf2lSyU6NYPqGNs6S1pqhvLaUETR /ZL84bjhf7Xw3JQiEbC86BHMSatfbPAQ0jN6Ookkr9PFPpVAWL4t2tXnm5OFaxcwiy+Rgb HMiNUYKReStDJJis6IKdXYDkU5UTasA= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=lQS9HNn2; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf06.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.186 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1761675167; a=rsa-sha256; cv=none; b=yrqqfSrXidIlKulOCKypuTsAivQKyDurRERPNxD72ohE4Ap2R0Zh67oibKTIel6h2h6jaC HNjyyBw6wUPm1rzWaUr/F+GBu7h5+RcTaOPIa4gbeghmUEi2tjU1xyjLAPWzF5+l7WphUo wk0UrQZXXNOri4bpA9nh5fUqqvP65yE= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1761675164; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/mIcK7vCMiNf076l+LaWZKI497HGob3OxvsLoIs/FEg=; b=lQS9HNn2xXA7sE3Ntv4jDLBzYAliouwdGZ+N3LRU21VyhFQwa6LZ/qS98WN3YIK0dl7m/U IPp6lysrkH4QjjvO5HK/WAeejgtUQvlJMHCCSokVJGYZHi6pBnr5uI9D9SY/4jb4sywY3j /EM9m2P5QogpPrIXFP7YPVLZbXSyLmo= From: Roman Gushchin To: Tejun Heo Cc: Andrew Morton , linux-kernel@vger.kernel.org, Alexei Starovoitov , Suren Baghdasaryan , Michal Hocko , Shakeel Butt , Johannes Weiner , Andrii Nakryiko , JP Kobryn , linux-mm@kvack.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Kumar Kartikeya Dwivedi Subject: Re: [PATCH v2 08/23] mm: introduce BPF kfuncs to deal with memcg pointers In-Reply-To: (Tejun Heo's message of "Tue, 28 Oct 2025 07:42:52 -1000") References: <20251027231727.472628-1-roman.gushchin@linux.dev> <20251027231727.472628-9-roman.gushchin@linux.dev> Date: Tue, 28 Oct 2025 11:12:35 -0700 Message-ID: <87y0ouuc8c.fsf@linux.dev> MIME-Version: 1.0 Content-Type: text/plain X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 36900180003 X-Rspamd-Server: rspam03 X-Stat-Signature: sq5ykj3qo3d4dty4p595jmtd6biebdqf X-HE-Tag: 1761675166-121384 X-HE-Meta: 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 3dglDtpt fKRHSvKe9CvMqDrpRkudVPMPx2uJAnEwp7f6cLBKPvS3rIMZeIlG16Ay39Z/1DeUwUkBViriougOrvN4Bejuyb5rKS8DuchOtUaeu14twT2NaCGkTOKBr+lI8Uf0M7CthvaJtHcm0pyL9LERrSJIIRs0OBkUmdlaoHrlczEF6bA6TLbay55OSjOIDeQ== 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: Tejun Heo writes: > On Mon, Oct 27, 2025 at 04:17:11PM -0700, Roman Gushchin wrote: >> +__bpf_kfunc struct mem_cgroup * >> +bpf_get_mem_cgroup(struct cgroup_subsys_state *css) >> +{ >> + struct mem_cgroup *memcg = NULL; >> + bool rcu_unlock = false; >> + >> + if (!root_mem_cgroup) >> + return NULL; >> + >> + if (root_mem_cgroup->css.ss != css->ss) { >> + struct cgroup *cgroup = css->cgroup; >> + int ssid = root_mem_cgroup->css.ss->id; >> + >> + rcu_read_lock(); >> + rcu_unlock = true; >> + css = rcu_dereference_raw(cgroup->subsys[ssid]); > > Would it make more sense to use cgroup_e_css()? Good call, will update in the next version. Thank you!