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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1761668192; 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=1ftyXtMKJiXGvCol0LZq8LgVSc8+XJJVccDr9V2Jw64=; b=mN8LxUn58/1ZZZ/JYFD69p+VTvbUvckaGk22+fnxe34+5t8PYP10haz/y/SISWoUsxA52i u2y1/eANPZbA7rvm3e3BNQsgR1RxKB6lu7ZYWnW4DAGhlmqfK0IzwereJpZoSEIvhmA+1m D30KR/rPZMO1xkVGtlPFPmVGFEUYDMw= From: Roman Gushchin To: bot+bpf-ci@kernel.org Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, ast@kernel.org, surenb@google.com, mhocko@kernel.org, shakeel.butt@linux.dev, hannes@cmpxchg.org, andrii@kernel.org, inwardvessel@gmail.com, linux-mm@kvack.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, martin.lau@kernel.org, song@kernel.org, memxor@gmail.com, tj@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, yonghong.song@linux.dev, clm@meta.com, ihor.solodrai@linux.dev Subject: Re: [PATCH v2 10/23] mm: introduce BPF kfuncs to access memcg statistics and events In-Reply-To: <45ee5e2e857a2e4022eb380f854d2a7cf27f3ec97d75a0200b46be95ae921d3b@mail.kernel.org> (bot's message of "Mon, 27 Oct 2025 23:48:14 +0000 (UTC)") References: <20251027231727.472628-11-roman.gushchin@linux.dev> <45ee5e2e857a2e4022eb380f854d2a7cf27f3ec97d75a0200b46be95ae921d3b@mail.kernel.org> Date: Tue, 28 Oct 2025 09:16:23 -0700 Message-ID: <87cy6757e0.fsf@linux.dev> MIME-Version: 1.0 Content-Type: text/plain X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam05 X-Stat-Signature: fof4fyz4bo4qmtu6xhhco5fnc7g9f3e1 X-Rspam-User: X-Rspamd-Queue-Id: 56BEF20019 X-HE-Tag: 1761668198-60038 X-HE-Meta: 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 XHlNGlju wIgTiSRRhDQjGQ3HPLxj8TeGt+XeoASNIbxZg8Z1nbWgiMPRe/YMmLbDzmsh5C2i+Pk02z5aGF2Em4Du3aNaDVkayJRg6oeew4SCeZN1FnZBU6JQYq4mtsfT2l/BlVkIkMc07pmuorTUH19036sxiiph+bqEE9K82UyH/h6lYyvY0Bj78s0hydXKs7O/LiDWOdLpugcj3fbJN4yLA6oWpJGxjvu/XwcmALOhqNsVKaM8t5vMXQqVFe/667FfZt30mjxhjzROz8uXLKl65PxGcPQ3M6IUr9wCVYi+xRnt3HomgiYY= 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: bot+bpf-ci@kernel.org writes: > ``` > commit 96abfe0549713749f00e32bff919a759db284a58 > Author: Roman Gushchin > > mm: introduce BPF kfuncs to access memcg statistics and events > > This patch adds four new BPF kfuncs for accessing memory cgroup statistics > and events, making them available to all BPF program types for implementing > OOM policies and accelerating memcg data access. > >> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h >> index 39a6c7c87..b9e08dddd 100644 >> --- a/include/linux/memcontrol.h >> +++ b/include/linux/memcontrol.h > > [ ... ] > >> diff --git a/mm/bpf_memcontrol.c b/mm/bpf_memcontrol.c >> index 76c342318..387255b8a 100644 >> --- a/mm/bpf_memcontrol.c >> +++ b/mm/bpf_memcontrol.c > > [ ... ] > >> @@ -75,6 +75,56 @@ __bpf_kfunc void bpf_put_mem_cgroup(struct mem_cgroup *memcg) >> css_put(&memcg->css); >> } >> >> +/** >> + * bpf_mem_cgroup_vm_events - Read memory cgroup's vm event counter >> + * @memcg: memory cgroup >> + * @event: event id >> + * >> + * Allows to read memory cgroup event counters. >> + */ >> +__bpf_kfunc unsigned long bpf_mem_cgroup_vm_events(struct mem_cgroup *memcg, >> + enum vm_event_item event) >> +{ >> + return memcg_events(memcg, event); >> +} >> + >> +/** >> + * bpf_mem_cgroup_usage - Read memory cgroup's usage >> + * @memcg: memory cgroup >> + * >> + * Returns current memory cgroup size in bytes. >> + */ >> +__bpf_kfunc unsigned long bpf_mem_cgroup_usage(struct mem_cgroup *memcg) >> +{ >> + return page_counter_read(&memcg->memory); >> +} > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > The documentation says this returns bytes, but page_counter_read() returns > pages. In mm/memcontrol-v1.c, the existing mem_cgroup_usage() function's > return value is multiplied by PAGE_SIZE to convert to bytes: > > return (u64)mem_cgroup_usage(memcg, false) * PAGE_SIZE; > > Should this function multiply the result by PAGE_SIZE to match its > documentation, or should the documentation be updated to say it returns > pages? Yep, correct, fixed.