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[91.12.103.101]) by smtp.gmail.com with ESMTPSA id g13sm1408508wmk.37.2021.11.23.06.44.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Nov 2021 06:44:04 -0800 (PST) Message-ID: Date: Tue, 23 Nov 2021 15:44:03 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Content-Language: en-US To: Jason Gunthorpe Cc: Jens Axboe , Andrew Dona-Couch , Andrew Morton , Drew DeVault , Ammar Faizi , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, io_uring Mailing List , Pavel Begunkov , linux-mm@kvack.org References: <20211116114727.601021d0763be1f1efe2a6f9@linux-foundation.org> <20211116133750.0f625f73a1e4843daf13b8f7@linux-foundation.org> <8f219a64-a39f-45f0-a7ad-708a33888a3b@www.fastmail.com> <333cb52b-5b02-648e-af7a-090e23261801@redhat.com> <5f998bb7-7b5d-9253-2337-b1d9ea59c796@redhat.com> <20211123132523.GA5112@ziepe.ca> <10ccf01b-f13a-d626-beba-cbee70770cf1@redhat.com> <20211123140709.GB5112@ziepe.ca> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH] Increase default MLOCK_LIMIT to 8 MiB In-Reply-To: <20211123140709.GB5112@ziepe.ca> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23.11.21 15:07, Jason Gunthorpe wrote: > On Tue, Nov 23, 2021 at 02:39:19PM +0100, David Hildenbrand wrote: >>> >>>> 2) Could be provide a mmu variant to ordinary users that's just good >>>> enough but maybe not as fast as what we have today? And limit >>>> FOLL_LONGTERM to special, privileged users? >>> >>> rdma has never been privileged >> >> Feel free to correct me if I'm wrong: it requires special networking >> hardware and the admin/kernel has to prepare the system in a way such >> that it can be used. > > Not really, plug in the right PCI card and it works Naive me would have assumed that the right modules have to be loaded (and not blacklisted), that there has to be an rdma service installed and running, that the NIC has to be configured in some way, and that there is some kind of access control which user can actually use which NIC. For example, I would have assume from inside a container it usually wouldn't just work. But I am absolutely not a networking and RDMA expert, so I have to believe what you say and I trust your experience :) So could as well be that on such a "special" (or not so special) systems there should be a way to restrict it to privileged users only. > > "special" is a bit of a reach since almost every NIC sold in the > 100GB > segment supports some RDMA. -- Thanks, David / dhildenb