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[195.250.132.146]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43d1e4d58e5sm50268531f8f.23.2026.04.07.05.48.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Apr 2026 05:48:07 -0700 (PDT) Date: Tue, 7 Apr 2026 14:48:05 +0200 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Eric Chanudet Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Maarten Lankhorst , Maxime Ripard , Natalie Vock , Tejun Heo , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, "T.J. Mercier" , Christian =?utf-8?B?S8O2bmln?= , Maxime Ripard , Albert Esteve , Dave Airlie Subject: Re: [PATCH RFC 2/2] cgroup/dmem: add a node to double charge in memcg Message-ID: References: <20260403-cgroup-dmem-memcg-double-charge-v1-0-c371d155de2a@redhat.com> <20260403-cgroup-dmem-memcg-double-charge-v1-2-c371d155de2a@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="3iqnq37lhwpyhhg3" Content-Disposition: inline In-Reply-To: <20260403-cgroup-dmem-memcg-double-charge-v1-2-c371d155de2a@redhat.com> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5441020015 X-Stat-Signature: zghws81n9z4igb3m43uzgj1zi7ra9awx X-Rspam-User: X-HE-Tag: 1775566089-598873 X-HE-Meta: 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 thlvoTAJ 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --3iqnq37lhwpyhhg3 Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH RFC 2/2] cgroup/dmem: add a node to double charge in memcg MIME-Version: 1.0 Hi. On Fri, Apr 03, 2026 at 10:08:36AM -0400, Eric Chanudet wrote: > Introduce /cgroupfs/<>/dmem.memcg to make allocations in a dmem > controlled region also be charged in memcg. >=20 > This is disabled by default and requires the administrator to configure > it through the cgroupfs before the first charge occurs. This somehow dropped the reason from [1] that this should be per-cgroup controllable. Is that still valid? (Otherwise, I'd ask why not make this a simple boot cmdline parameter like cgroup.memory=3Dnokmem.) > @@ -624,6 +656,13 @@ void dmem_cgroup_uncharge(struct dmem_cgroup_pool_st= ate *pool, u64 size) > return; > =20 > page_counter_uncharge(&pool->cnt, size); > + > + struct mem_cgroup *memcg =3D mem_cgroup_from_cgroup(pool->cs->css.cgrou= p); This is not necessarily same memcg as when the dmem was charged via current (imagine dmem controller to depth N, but memcg only to N-1; charge, then memcg is enabled up to N so this would attempt uncharge =66rom new memcg at level N, possibly going negative). There is a question whether dmem should enforce same-depth hierarchies with `dmem_cgrp_subsys.depends_on =3D 1 << memory_cgrp_id` (see io_cgrp_subsys for comparison). And eventually, if per-cgroup attribute is desired, it would make greater sense to me if that attribute was on the parent level, so that siblings competing among each other are always of the same composition (i.e. all w/out dmem or all including dmem). This likely results in this extra-charging attribute to be properly hierarchical. HTH, Michal [1] https://lore.kernel.org/all/a446b598-5041-450b-aaa9-3c39a09ff6a0@amd.co= m/ --3iqnq37lhwpyhhg3 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJEEABYKADkWIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCadT9ARsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIACgkQfj0C55Tb+AhOewD9F+F9qnpuYx39EPNVVkg/ SKfJIBup3dSTrvEji8kA2RQA/RMerQbaK2QZn1VEv4D6kzXZgky62HGmS4B6FfWf 8XoH =uSlM -----END PGP SIGNATURE----- --3iqnq37lhwpyhhg3--