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[109.81.30.110]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47a82d26f5asm29905245e9.5.2025.12.10.00.05.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Dec 2025 00:05:43 -0800 (PST) Date: Wed, 10 Dec 2025 09:05:42 +0100 From: Michal Hocko To: Chen Ridong Cc: hannes@cmpxchg.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, akpm@linux-foundation.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, david@kernel.org, zhengqi.arch@bytedance.com, lorenzo.stoakes@oracle.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, lujialin4@huawei.com Subject: Re: [PATCH -next v2 2/2] memcg: remove mem_cgroup_size() Message-ID: References: <20251210071142.2043478-1-chenridong@huaweicloud.com> <20251210071142.2043478-3-chenridong@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251210071142.2043478-3-chenridong@huaweicloud.com> X-Rspamd-Queue-Id: D5D6140010 X-Stat-Signature: wftu9ohkb31kz6fiadwr4iyrxm1ghbrj X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1765353944-504407 X-HE-Meta: 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 yam6rL0i 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 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 Wed 10-12-25 07:11:42, Chen Ridong wrote: > From: Chen Ridong > > The mem_cgroup_size helper is used only in apply_proportional_protection > to read the current memory usage. Its semantics are unclear and > inconsistent with other sites, which directly call page_counter_read for > the same purpose. > > Remove this helper and replace its usage with page_counter_read for > clarity. Additionally, rename the local variable 'cgroup_size' to 'usage' > to better reflect its meaning. > > This change is safe because page_counter_read() is only called when memcg > is enabled in the apply_proportional_protection. > > No functional changes intended. I would prefer to keep the code as is. Btw. [...] > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 670fe9fae5ba..fe48d0376e7c 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2451,6 +2451,7 @@ static inline void calculate_pressure_balance(struct scan_control *sc, > static unsigned long apply_proportional_protection(struct mem_cgroup *memcg, > struct scan_control *sc, unsigned long scan) > { > +#ifdef CONFIG_MEMCG > unsigned long min, low; > > mem_cgroup_protection(sc->target_mem_cgroup, memcg, &min, &low); [...] > @@ -2508,6 +2509,7 @@ static unsigned long apply_proportional_protection(struct mem_cgroup *memcg, > */ > scan = max(scan, SWAP_CLUSTER_MAX); > } > +#endif > return scan; > } This returns a random garbage for !CONFIG_MEMCG, doesn't it? -- Michal Hocko SUSE Labs