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[195.250.132.146]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47be2723d19sm629127655e9.2.2025.12.29.02.52.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Dec 2025 02:52:53 -0800 (PST) Date: Mon, 29 Dec 2025 11:52:52 +0100 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Qi Zheng Cc: Shakeel Butt , Yosry Ahmed , hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Qi Zheng Subject: Re: [PATCH v2 00/28] Eliminate Dying Memory Cgroup Message-ID: References: <5dsb6q2r4xsi24kk5gcnckljuvgvvp6nwifwvc4wuho5hsifeg@5ukg2dq6ini5> <7enyz6xhyjjp5djpj7jnvqiymqfpmb2gmhmmj7r5rkzjyix7o7@mpxpa566abyd> <63c958ae-9db2-4da8-935b-a596cc8535d3@linux.dev> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="illqhsqtgan5bpog" Content-Disposition: inline In-Reply-To: <63c958ae-9db2-4da8-935b-a596cc8535d3@linux.dev> X-Stat-Signature: i8wz6aun8tq4h59ccyj5hjnx9jue6w1s X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 125B4C000D X-Rspam-User: X-HE-Tag: 1767005575-96569 X-HE-Meta: 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 rA2hoCmQ mukLxRTpt/51WTUDQlmyQ2WsF1Eb3bCLmZHLIR3IqH/wXC6Z6PV8C4oS670a5ZLFH56dk/pWI06YUR8a0q88xqb+feLiLK9bSwlbAVu1kzS4RPUgLvKNWHKd9VjEB+HjnLfaHxgl3SVS/illl68XqvmS0plVp9DAxq3oOGc7XLamyf7tUNDDvN6zwpLkTermTy1EHDiqxHNUmtx5xz3rCfeM6VvTtHoSrTkBn2l+wdWrZDDnd+74dQOszdrG0J7WpPqCW6M2FgwGsng4lgOtVRGZWY3REz5zfHFGH9+zsCcNSU25NGJC13/I/wD/ZE58rG4rz05VRYt8ybJTrjlSbrgJl5/H4pFcaMDFHuIGEnKiuz4Nak7BsrakFFhZNV0HCI8PCAeLNbvrpoF5wVlVEB+Gnxf9QBpu3v5hLB4wcINbeFdaJGrKLZfU8Eg== 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: --illqhsqtgan5bpog Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v2 00/28] Eliminate Dying Memory Cgroup MIME-Version: 1.0 On Tue, Dec 23, 2025 at 04:36:18PM -0800, Shakeel Butt wrote: =2E.. > The core stats update functions are mod_memcg_state() and > mod_memcg_lruvec_state(). If for v1 only, we add additional check for > CSS_DYING and go to parent if CSS_DYING is set then shouldn't we avoid > this issue? =2E..and go to first !CSS_DYING ancestor :-/ (as the whole chain of memcgs can be offlined) IIUC thanks to the reparenting charging (modifying state) to an offlined memcg should be an exception... On Mon, Dec 29, 2025 at 05:42:43PM +0800, Qi Zheng wro= te: > > We do reparenting in css_offline() callback and cgroup offlining > > happen somewhat like this: > >=20 > > 1. Set CSS_DYING > > 2. Trigger percpu ref kill > > 3. Kernel makes sure css ref killed is seen by all CPUs and then trigger > > css_offline callback. >=20 > it seems that we can add the following to > mem_cgroup_css_free(): >=20 > parent->vmstats->state_local +=3D child->vmstats->state_local; >=20 > Right? I will continue to take a closer look. =2E..and the time between offlining and free'ing a memcg should not be arbitrarily long anymore (right?, the crux of the series). So only transferring local stats in mem_cgroup_css_free should yield a correct result after limited time range (with possible underflows between) with no special precaution for CSS_DYING on charging side. 0.02=E2=82=AC, Michal --illqhsqtgan5bpog Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJEEABYKADkWIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCaVJdgRsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMSwyLDIACgkQfj0C55Tb+Ah51gD/doiKV5VyTZFiXLb4HtUI bo6/lt/P2BnUD8eq16i80doA/2jQKFn6l9VxvBFRi5i/AuI8/e+ynY2uvwooHwCr c5IO =7fmn -----END PGP SIGNATURE----- --illqhsqtgan5bpog--