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([2620:10d:c090:500::5:e774]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-33bd79dda6fsm337108a91.10.2025.10.16.13.28.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Oct 2025 13:28:17 -0700 (PDT) Message-ID: Date: Thu, 16 Oct 2025 13:28:15 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] memcg: introduce kfuncs for fetching memcg stats To: Song Liu Cc: shakeel.butt@linux.dev, andrii@kernel.org, ast@kernel.org, mkoutny@suse.com, yosryahmed@google.com, hannes@cmpxchg.org, tj@kernel.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, kernel-team@meta.com References: <20251015190813.80163-1-inwardvessel@gmail.com> <20251015190813.80163-2-inwardvessel@gmail.com> Content-Language: en-US From: JP Kobryn In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/15/25 4:12 PM, Song Liu wrote: > On Wed, Oct 15, 2025 at 12:08 PM JP Kobryn wrote: >> > [...] >> --- >> mm/memcontrol.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 67 insertions(+) >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index 4deda33625f4..6547c27d4430 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -871,6 +871,73 @@ unsigned long memcg_events_local(struct mem_cgroup *memcg, int event) >> } >> #endif >> >> +static inline struct mem_cgroup *memcg_from_cgroup(struct cgroup *cgrp) >> +{ >> + return cgrp ? mem_cgroup_from_css(cgrp->subsys[memory_cgrp_id]) : NULL; >> +} >> + > > We should add __bpf_kfunc_start_defs() here, and __bpf_kfunc_end_defs() > after all the kfuncs. Good call. > >> +__bpf_kfunc static void memcg_flush_stats(struct cgroup *cgrp) > > We mostly do not make kfunc static, but it seems to also work. > >> +{ >> + struct mem_cgroup *memcg = memcg_from_cgroup(cgrp); >> + >> + if (!memcg) >> + return; > > Maybe we can let memcg_flush_stats return int, and return -EINVAL > on memcg == NULL cases? Sure, I'll do that in v3. > >> + >> + mem_cgroup_flush_stats(memcg); >> +} >> + > [...]