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AJvYcCWRyMA3JOjz9TGW6wLJxVu1yC7ze8HE6eWAAhBIjdBlAL6kzWxaw1wUkrqF4s6/7p3j4m1wmzEvZw==@kvack.org X-Gm-Message-State: AOJu0YzQD8qdyOe9ZkTnwP7/kdc8g93/sqaRovTx/VYLJDiqVhhYhD0X z0wHY7NRVWtVSzqc47DfowCI57ziLCDAqZotWFg4JBAUN9hLtwDkmLcHtqoU3vc6lGcXaltrlJf 2djZPNMqzpVmpiovPH7PNgGuf0JI= X-Gm-Gg: ASbGncuKiL2hIh99aH+0j+gsT/zHjR9SOujgVLfw3o/3DfoSlmHJ23jOMo+8R3WesuC xIUmu3rvzx08sKNQe9bzzDpILka/TEmnVee4Akk49DjvQUuVYmCo+7rh35yqVQ0IrddQVbPicbZ EQ1hUxp9HiZ8xlnRfNRMLjViIa X-Google-Smtp-Source: AGHT+IGa2ATWEnPtBZKrovC/2tQXOIHQaYNh/KXGz4WWHKDhRqKyDzgdS0ONK7AXu9tKvknpMnQpqfeFIU5BV3Y+5xU= X-Received: by 2002:a17:906:1718:b0:ac7:391b:e684 with SMTP id a640c23a62f3a-ac7391beac4mr794735366b.58.1743453835197; Mon, 31 Mar 2025 13:43:55 -0700 (PDT) MIME-Version: 1.0 References: <20250310-dmem-cgroups-v1-0-2984c1bc9312@kernel.org> <20250310-eccentric-wonderful-puffin-ddbb26@houat> In-Reply-To: <20250310-eccentric-wonderful-puffin-ddbb26@houat> From: Dave Airlie Date: Tue, 1 Apr 2025 06:43:43 +1000 X-Gm-Features: AQ5f1Jo63dx6IuKsG5SoyFqmX486Pcaveqb15lGzyp5QvSc5pKKZ1U2dlNV04bE Message-ID: Subject: Re: [PATCH RFC 00/12] dma: Enable dmem cgroup tracking To: Maxime Ripard Cc: =?UTF-8?Q?Christian_K=C3=B6nig?= , Andrew Morton , Marek Szyprowski , Robin Murphy , Sumit Semwal , Benjamin Gaignard , Brian Starkey , John Stultz , "T.J. Mercier" , Maarten Lankhorst , Thomas Zimmermann , Simona Vetter , Tomasz Figa , Mauro Carvalho Chehab , Ben Woodard , Hans Verkuil , Laurent Pinchart , linux-mm@kvack.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 094F44000C X-Stat-Signature: ptjw7g1giu9h1rqa5z7nj8h1j5jznrdq X-HE-Tag: 1743453836-860529 X-HE-Meta: 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 HYSl9a3S unRnN4d48nUMLPrBMYAOha5vB2/tLky2tzAeEAARCFmRoYpbwattMgmbvtHVbeU1OVFYNG4htHdoIgSwiSbwfMlRmLr8XuAeptBvyiPSv2azValZBa1ayKx1qM158G7z1PdBjpXwKeIh3dNwUMRJo4iuqpufbWgstjgaO7Btx1/KgJmIeLGukj2iMJAbPBQyRGUkhcWxaA3qNHLpBvaJcubTeZW06sKwa8z62RQlcoeg/+nls4RHBiGfIgyn4BuGxEvu8CYSB1KbzHq2L+HRxj+4ByLQZna6zcoHCfjLI9CrQxyCSA2vnhKvpJE5nJk6y31asjzPZD4dEVMsbp7ClhqJZgDzV5g1lMGvBx9RMxnYmXrKujopZlvnpU+ZIwGNEiJ+QHOy9Ox7EE4ux9BDCSgVpMWa3IApGFX5a 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 Tue, 11 Mar 2025 at 00:26, Maxime Ripard wrote: > > Hi, > > On Mon, Mar 10, 2025 at 03:16:53PM +0100, Christian K=C3=B6nig wrote: > > [Adding Ben since we are currently in the middle of a discussion > > regarding exactly that problem] > > > > Just for my understanding before I deep dive into the code: This uses > > a separate dmem cgroup and does not account against memcg, don't it? > > Yes. The main rationale being that it doesn't always make sense to > register against memcg: a lot of devices are going to allocate from > dedicated chunks of memory that are either carved out from the main > memory allocator, or not under Linux supervision at all. > > And if there's no way to make it consistent across drivers, it's not the > right tool. > While I agree on that, if a user can cause a device driver to allocate memory that is also memory that memcg accounts, then we have to interface with memcg to account that memory. The pathological case would be a single application wanting to use 90% of RAM for device allocations, freeing it all, then using 90% of RAM for normal usage. How to create a policy that would allow that with dmem and memcg is difficult, since if you say you can do 90% on both then the user can easily OOM the system. Dave. > Maxime