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Tue, 22 Sep 2026 05:30:38 -0700 (PDT) Received: from jlelli-thinkpadt14gen4.remote.csb ([176.206.14.6]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49fdad53b53sm46426695e9.14.2026.09.22.05.30.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Sep 2026 05:30:36 -0700 (PDT) Date: Tue, 22 Sep 2026 14:30:34 +0200 From: Juri Lelli To: Hui Su Cc: Ingo Molnar , Peter Zijlstra , Vincent Guittot , Mikhail Zaslonko , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Luca Abeni , Daniel Bristot de Oliveira , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] sched/deadline: Reject debugfs dl_server writes for inactive CPUs Message-ID: References: <20260919153150.2618403-1-sh_def@163.com> <20260919153150.2618403-3-sh_def@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260919153150.2618403-3-sh_def@163.com> Hello, On 20/09/26 00:31, Hui Su wrote: > Commit 4043f5498416 ("sched/deadline: Reject debugfs dl_server writes > for offline CPUs") rejects per-CPU DL server parameter updates once the > target CPU is offline. > > During CPU hot-unplug, however, the CPU is cleared from cpu_active_mask > before it is marked offline. This leaves a window where the CPU is no > longer active but cpu_online() still returns true, so > sched_server_write_common() continues to accept DL server updates. > > There is no meaningful reason to reconfigure a per-CPU DL server once the > CPU is being deactivated. Reject the write when the target CPU is inactive > rather than only after it becomes offline. > > Fixes: d741f297bcea ("sched/fair: Fair server interface") Isn't 4043f5498416 ("sched/deadline: Reject debugfs dl_server writes for offline CPUs") more appropriate? > Reported-by: Sashiko > Link: https://lore.kernel.org/r/anw7IML1xzHys6re@jlelli-thinkpadt14gen4.remote.csb > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Hui Su > --- Apart from that the fix looks good to me. Acked-by: Juri Lelli Thanks, Juri