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Fri, 13 Mar 2026 06:48:15 -0700 (PDT) X-Received: by 2002:a05:600c:4e16:b0:483:6d4a:7e6d with SMTP id 5b1f17b1804b1-4855670cd92mr51728245e9.30.1773409694786; Fri, 13 Mar 2026 06:48:14 -0700 (PDT) Received: from jlelli-thinkpadt14gen4.remote.csb ([151.29.82.96]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4854b5e9179sm207199645e9.3.2026.03.13.06.48.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Mar 2026 06:48:14 -0700 (PDT) Date: Fri, 13 Mar 2026 14:48:11 +0100 From: Juri Lelli To: John Stultz Cc: LKML , K Prateek Nayak , Peter Zijlstra , Joel Fernandes , Qais Yousef , Ingo Molnar , Vincent Guittot , Dietmar Eggemann , Valentin Schneider , Steven Rostedt , Ben Segall , Zimuzo Ezeozue , Mel Gorman , Will Deacon , Waiman Long , Boqun Feng , "Paul E. McKenney" , Metin Kaya , Xuewen Yan , Thomas Gleixner , Daniel Lezcano , Suleiman Souhlal , kuyo chang , hupu , kernel-team@android.com Subject: Re: [PATCH v25 1/9] sched: Make class_schedulers avoid pushing current, and get rid of proxy_tag_curr() Message-ID: References: <20260313023022.2902479-1-jstultz@google.com> <20260313023022.2902479-2-jstultz@google.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: <20260313023022.2902479-2-jstultz@google.com> Hello, On 13/03/26 02:30, John Stultz wrote: ... > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index d08b004293234..4e746f4de6529 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -2801,12 +2801,24 @@ static int find_later_rq(struct task_struct *task) > > static struct task_struct *pick_next_pushable_dl_task(struct rq *rq) > { > - struct task_struct *p; > + struct task_struct *p = NULL; > + struct rb_node *next_node; > > if (!has_pushable_dl_tasks(rq)) > return NULL; > > - p = __node_2_pdl(rb_first_cached(&rq->dl.pushable_dl_tasks_root)); > + next_node = rb_first_cached(&rq->dl.pushable_dl_tasks_root); > + while (next_node) { > + p = __node_2_pdl(next_node); > + /* make sure task isn't on_cpu (possible with proxy-exec) */ > + if (!task_on_cpu(rq, p)) > + break; > + > + next_node = rb_next(next_node); > + } > + > + if (!p) > + return NULL; Can't this return an on_cpu task if we hit the corner case where all pushable tasks are on_cpu? Thanks, Juri