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[2003:d8:2f0a:ca00:f74f:2017:1617:3ec3]) by smtp.gmail.com with ESMTPSA id e38-20020a05600c4ba600b003dc434900e1sm11512963wmp.34.2023.01.31.06.00.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 31 Jan 2023 06:00:10 -0800 (PST) Message-ID: <658eda9c-d716-fcb7-ba0c-b36f646195f1@redhat.com> Date: Tue, 31 Jan 2023 15:00:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [RFC PATCH 01/19] mm: Introduce vm_account To: Alistair Popple , linux-mm@kvack.org, cgroups@vger.kernel.org Cc: linux-kernel@vger.kernel.org, jgg@nvidia.com, jhubbard@nvidia.com, tjmercier@google.com, hannes@cmpxchg.org, surenb@google.com, mkoutny@suse.com, daniel@ffwll.ch, linuxppc-dev@lists.ozlabs.org, linux-fpga@vger.kernel.org, linux-rdma@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, netdev@vger.kernel.org, io-uring@vger.kernel.org, bpf@vger.kernel.org, rds-devel@oss.oracle.com, linux-kselftest@vger.kernel.org References: <748338ffe4c42d86669923159fe0426808ecb04d.1674538665.git-series.apopple@nvidia.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <748338ffe4c42d86669923159fe0426808ecb04d.1674538665.git-series.apopple@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2625120012 X-Stat-Signature: pzdxcjw6d1k1fcz5ksby97ocyf98p1b3 X-HE-Tag: 1675173621-964411 X-HE-Meta: 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 B04a3glc XB2WPqI5xMsApj+bJeddP+WFI95s34NyLQl+JQEMkgEkMTyDPGSaluevF8n73kGDaXUhf+hVyg3SSAR9YqUO/3uLRxbsSpUHyV33rVX2i06XdoMdgYNz2YfwHDNk+jHZl4qggsBejxyCJickYiniumKRVptABcoaDKK6UsNi1VrYOIB05/iXF9ZPNAHtKyf8PZcuMMOntA3U40jCvn9WyOBOcTocMcVCwbIQ1tsiNbUJ280Rx5R45FXlngJFk2T98vyyCVsLrhNpEJO65ORWwQ8UUZmHAgDEfTyYyyGBtYu6KeAa8utG3zXuYlqVzRyTpy3EY52Z3SE5POQJY/p2iO+/2iR87GgeOKarr+xlzdEuV8lBzwNKhcL3vGM3gcQKKmCOUqL+3bwIg/BXqS22pv0LOhrIBkgZhYUa6UzjR5sTa5mHOi50B+olVx/T1lsFGx4BK 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: On 24.01.23 06:42, Alistair Popple wrote: > Kernel drivers that pin pages should account these pages against > either user->locked_vm or mm->pinned_vm and fail the pinning if > RLIMIT_MEMLOCK is exceeded and CAP_IPC_LOCK isn't held. > > Currently drivers open-code this accounting and use various methods to > update the atomic variables and check against the limits leading to > various bugs and inconsistencies. To fix this introduce a standard > interface for charging pinned and locked memory. As this involves > taking references on kernel objects such as mm_struct or user_struct > we introduce a new vm_account struct to hold these references. Several > helper functions are then introduced to grab references and check > limits. > > As the way these limits are charged and enforced is visible to > userspace we need to be careful not to break existing applications by > charging to different counters. As a result the vm_account functions > support accounting to different counters as required. > > A future change will extend this to also account against a cgroup for > pinned pages. The term "vm_account" is misleading, no? VM_ACCOUNT is for accounting towards the commit limit .... -- Thanks, David / dhildenb