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Mon, 09 Nov 2026 07:09:16 -0800 (PST) X-Received: by 2002:a05:600d:82ea:b0:4a7:7f3f:6f8e with SMTP id 5b1f17b1804b1-4b943f76d81mr96594555e9.0.1794236955393; Mon, 09 Nov 2026 07:09:15 -0800 (PST) Received: from jlelli-thinkpadt14gen4.remote.csb ([151.29.158.90]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4b7e32ad4d1sm255269375e9.5.2026.11.09.07.09.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2026 07:09:14 -0800 (PST) Date: Mon, 9 Nov 2026 16:09:12 +0100 From: Juri Lelli To: Mathieu Desnoyers Cc: peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, tglx@kernel.org, will@kernel.org, boqun@kernel.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, luca.abeni@santannapisa.it, mathieu.poirier@linaro.org, longman@redhat.com, ridong.chen@linux.dev, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, shuah@kernel.org, bigeasy@linutronix.de, clrkwllms@kernel.org, parri.andrea@gmail.com, m.szyprowski@samsung.com, kayracizmeci@gmail.com, weihengqiuu@gmail.com, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-rt-devel@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH v5 05/29] sched/deadline: Do not divide by zero active CPUs of a root domain Message-ID: References: <20261108185406.1549770-1-mathieu.desnoyers@efficios.com> <20261108185406.1549770-6-mathieu.desnoyers@efficios.com> <3e6677a8-b972-4081-a080-e925fe1df3b0@efficios.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3e6677a8-b972-4081-a080-e925fe1df3b0@efficios.com> On 09/11/26 09:57, Mathieu Desnoyers wrote: > On 2026-11-09 09:30, Juri Lelli wrote: > [...] > > This 2nd hunk complements and tightens 4043f54984161 ("sched/deadline: > > Reject debugfs dl_server writes for offline CPUs") which has Fixes: > > d741f297bcea ("sched/fair: Fair server interface"). Do we need both > > fixes (if that is allowed) or maybe we need to split this change in two > > (as this second part won't apply to old kernels w/o dl-servers)? > > Good point. I will split it in two in the next version: > > - __dl_sub() and __dl_add() skip the division when the root domain has > no active CPU. Fixes: daec57983670. This alone removes the divide > error, on the debugfs path too. > - The debugfs write is refused while the runqueue is offline. Fixes: > 4043f5498416, which it completes for the hotplug windows. It only > applies where that commit is. Hummm, I'm not sure we can say it fixes 4043f5498416, which was a correct, but only incomplete, fix for d741f297bcea (which the second hunk fixes properly).