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[195.250.132.146]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47a8f38a4b7sm197204695e9.3.2025.12.15.08.28.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Dec 2025 08:28:22 -0800 (PST) Date: Mon, 15 Dec 2025 17:28:20 +0100 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Chen Ridong Cc: hannes@cmpxchg.org, mhocko@kernel.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 v3 2/2] memcg: remove mem_cgroup_size() Message-ID: References: <20251211013019.2080004-1-chenridong@huaweicloud.com> <20251211013019.2080004-3-chenridong@huaweicloud.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="6lc2v3gcqh4z4ltd" Content-Disposition: inline In-Reply-To: <20251211013019.2080004-3-chenridong@huaweicloud.com> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 717D04000B X-Stat-Signature: 8by4i6r76rmf9imwine9y476s3rx84mt X-HE-Tag: 1765816104-941561 X-HE-Meta: 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 CCQlZXvq 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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: --6lc2v3gcqh4z4ltd Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH -next v3 2/2] memcg: remove mem_cgroup_size() MIME-Version: 1.0 Hi Ridong. On Thu, Dec 11, 2025 at 01:30:19AM +0000, Chen Ridong wrote: > From: Chen Ridong >=20 > 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. >=20 > Remove this helper and get its usage via mem_cgroup_protection for > clarity. Additionally, rename the local variable 'cgroup_size' to 'usage' > to better reflect its meaning. >=20 > No functional changes intended. >=20 > Signed-off-by: Chen Ridong Why does mem_cgroup_calculate_protection "calculate" usage for its callers? Couldn't you just the change source in apply_proportional_protection()? Thanks, Michal > @@ -2485,7 +2485,6 @@ static unsigned long apply_proportional_protection(= struct mem_cgroup *memcg, > * again by how much of the total memory used is under > * hard protection. > */ > - unsigned long cgroup_size =3D mem_cgroup_size(memcg); + unsigned long cgroup_size =3D page_counter_read(memcg); > unsigned long protection; > =20 > /* memory.low scaling, make sure we retry before OOM */ > @@ -2497,9 +2496,9 @@ static unsigned long apply_proportional_protection(= struct mem_cgroup *memcg, > } > =20 > /* Avoid TOCTOU with earlier protection check */ > - cgroup_size =3D max(cgroup_size, protection); > + usage =3D max(usage, protection); > =20 > - scan -=3D scan * protection / (cgroup_size + 1); > + scan -=3D scan * protection / (usage + 1); > =20 > /* > * Minimally target SWAP_CLUSTER_MAX pages to keep --6lc2v3gcqh4z4ltd Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJEEABYKADkWIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCaUA3IhsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMSwyLDIACgkQfj0C55Tb+AhHDAEA3ePRl1oqqoJs1d3McZRX xevo8ebBHTd4DUJSJvbhJhwA/19a+3X/nxewd71A03xJ+bHGn1w01e1sr6huB0U7 URQP =OXfw -----END PGP SIGNATURE----- --6lc2v3gcqh4z4ltd--