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[109.81.30.110]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42f7cbe9070sm35533483f8f.7.2025.12.10.00.37.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Dec 2025 00:37:13 -0800 (PST) Date: Wed, 10 Dec 2025 09:37:12 +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> <9a9abc04-8915-40ac-ad40-2ae67d429ddb@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9a9abc04-8915-40ac-ad40-2ae67d429ddb@huaweicloud.com> On Wed 10-12-25 16:31:37, Chen Ridong wrote: > > > On 2025/12/10 16:05, Michal Hocko wrote: [...] > >> 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? > > > > This returns what was passed as input. This means the scan behavior remains unchanged when memcg is > disabled. When memcg is enabled, the scan amount may be proportionally scaled. Right you are. My bad. Sorry for the confusion. -- Michal Hocko SUSE Labs