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McKenney" Cc: Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Tejun Heo , Andrea Righi , rcu@vger.kernel.org, linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev, stable@vger.kernel.org, kernel-team@cloudflare.com, Matt Fleming Subject: Re: [PATCH] rcu-tasks: Defer IRQ-disabled callback enqueue to irq_work Message-ID: References: <20260713101245.3207634-1-matt@readmodwrite.com> Precedence: bulk X-Mailing-List: stable@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: <20260713101245.3207634-1-matt@readmodwrite.com> On Mon, Jul 13, 2026 at 11:12:45AM +0100, Matt Fleming wrote: > From: Matt Fleming > > call_rcu_tasks_generic() can be invoked with IRQs disabled, and on > older kernels this exposed an ABBA deadlock against the scheduler > runqueue lock via sched_ext's task-storage teardown path: > > CPU 0 CPU 1 > ----- ----- > sched_ext_free() > task_rq_lock() > raw_spin_lock(rq->lock) > rcu_tasks_one_gp() > raw_spin_lock(cbs_gbl_lock) > scx_exit_task() > bpf_task_storage_delete() > call_rcu_tasks_generic() > raw_spin_lock(cbs_gbl_lock) > > _printk() > console_unlock() > try_to_wake_up() > raw_spin_lock(rq->lock) > Hey Paul, it looks like this didn't get picked up and now won't apply cleanly to your tree. Should I submit a v2? Thanks, Matt