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b=smv/lP5o9CsLvG21j5v2Heg6EF/lysOnQHrQpZJiX8DtUg2Lq+g99CODEbIkkrZy5 OnjRJPcTk2LkvWjG2QWv+/uQ0Ww+4DXzENNaOCqTBqeroFUrss8437dc7sS66Uzdkd saBHMOWXQZgMHK0ZAe1/AA+uB1En7rv2Aefwc7TpOhguU26if64+pyj6FMRBrldQyP 0jKG+7WgPyu8hiTKfkeJC+GIk/EtN71fzJen24goMLtLwd4sZbowqCWy+tNdr6/Ezc 3z5sSEESJtbWEZHhKs1Y7lcFapuO723akp7KCBJlKkXmJurqWZgGNzlgHNtz186X/3 +mbeVR8ykC8LQ== Date: Tue, 28 Oct 2025 07:42:52 -1000 From: Tejun Heo To: Roman Gushchin 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 Message-ID: References: <20251027231727.472628-1-roman.gushchin@linux.dev> <20251027231727.472628-9-roman.gushchin@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251027231727.472628-9-roman.gushchin@linux.dev> X-Rspamd-Server: rspam05 X-Stat-Signature: ktjk83aga39951s1rm6fbw6ex841uj3i X-Rspam-User: X-Rspamd-Queue-Id: 1C88380008 X-HE-Tag: 1761673373-918546 X-HE-Meta: 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 qFrY+eTc 6o7GnQ4/+Fhe4XGpQqjb7H3kVNVGsbE0Dm82hnkCVf7t89FLK1SZZSvlMAKF7hZdGY5S6xKQoiZz3BQWFzlsz+8jeWTfSk2fj3kD/PiueDWKvnyGeBbNzYlUGKnbAmu0vDkJJ+ZEJypz8lUgu/OBrm31/D+wPQAAXgipWZT6RQIBrklBgCIuQDrC8Tvn3UOaELAubfzJyQ/At3qZxQ6Os1FkeZg== 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 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()? Thanks. -- tejun