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([2601:188:ca00:a00:f844:fad5:7984:7bd7]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6d3966303e6sm22089036d6.99.2024.11.08.10.47.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 08 Nov 2024 10:47:36 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: Date: Fri, 8 Nov 2024 13:47:35 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] sched/deadline: Skip overflow check if 0 capacity To: Juri Lelli , Waiman Long Cc: Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org, Phil Auld , Joel Fernandes References: <20241108042924.520458-1-longman@redhat.com> <735344cd-1c32-451f-904e-235578e1a360@redhat.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 11/8/24 11:31 AM, Juri Lelli wrote: > That said though, I believe I just found an additional issue. With the > above the system doesn't crash (it did w/o it), but happily moves > DEADLINE tasks out of a domain with a single CPU going offline. Last > time I looked at this we were properly checking and failing the hotplug > operation, but it was indeed a while ago, so not sure yet what changed. > More staring. > > Oh, so broken, yay. 🙂 Is it the case that the null total_bw bug let the cpu offline succeeds in a 1-cpu partition with a DL task and cause it to crash? I am also OK if you adds the check for the presence of a DL task in the cpu and fails the offline check in this case. Thanks, Longman