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18 Oct 2023 08:37:26 -0700 Message-ID: <7a1a5125-9da2-47b6-ba0f-cf24d84df16b@intel.com> Date: Wed, 18 Oct 2023 08:37:25 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 12/18] x86/sgx: Add EPC OOM path to forcefully reclaim EPC Content-Language: en-US To: Haitao Huang , =?UTF-8?Q?Michal_Koutn=C3=BD?= Cc: "Christopherson,, Sean" , "Huang, Kai" , "Zhang, Bo" , "linux-sgx@vger.kernel.org" , "cgroups@vger.kernel.org" , "yangjie@microsoft.com" , "dave.hansen@linux.intel.com" , "Li, Zhiquan1" , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , "tglx@linutronix.de" , "tj@kernel.org" , "anakrish@microsoft.com" , "jarkko@kernel.org" , "hpa@zytor.com" , "mikko.ylinen@linux.intel.com" , "Mehta, Sohil" , "bp@alien8.de" , "x86@kernel.org" , "kristen@linux.intel.com" References: <1f7a740f3acff8a04ec95be39864fb3e32d2d96c.camel@intel.com> <631f34613bcc8b5aa41cf519fa9d76bcd57a7650.camel@intel.com> <35a7fde056037a40b3b4b170e2ecd45bf8c4ba9f.camel@intel.com> <915907d56861ef4aa7f9f68e0eb8d136a60bee39.camel@intel.com> <6lrq4xmk42zteq6thpyah7jy25rmvkp7mqxtll6sl7z62m7n4m@vrbbedtgxeq4> <11413ca0-a8a9-4f73-8006-2e1231dbb390@intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: cgroups@vger.kernel.org On 10/18/23 08:26, Haitao Huang wrote: > Maybe not in sense of killing something. My understanding memory.reclaim > does not necessarily invoke the OOM killer. But what I really intend to > say is we can have a separate knob for user to express the need for > reducing the current usage explicitly and keep "misc.max' non-preemptive > semantics intact. When we implement that new knob, then we can define > what kind of reclaim for that. Depending on vEPC implementation, it may > or may not involve killing VMs. But at least that semantics will be > explicit for user. I'm really worried that you're going for "perfect" semantics here. This is SGX. It's *NOT* getting heavy use and even fewer folks will ever apply cgroup controls to it. Can we please stick to simple, easily-coded rules here? I honestly don't think these corner cases matter all that much and there's been *WAY* too much traffic in this thread for what is ultimately not that complicated. Focus on *ONE* thing: 1. Admin sets a limit 2. Enclave is created 3. Enclave hits limit, allocation fails Nothing else matters. What if the admin lowers the limit on an already-created enclave? Nobody cares. Seriously. What about inducing reclaim? Nobody cares. What about vEPC? Doesn't matter, an enclave page is an enclave page.