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[141.239.149.160]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fbb6ab6e40sm35688045ad.169.2024.07.10.09.39.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jul 2024 09:39:50 -0700 (PDT) Sender: Tejun Heo Date: Wed, 10 Jul 2024 06:39:49 -1000 From: Tejun Heo To: Peter Zijlstra Cc: Andrea Righi , void@manifault.com, linux-kernel@vger.kernel.org, kernel-team@meta.com, schatzberg.dan@gmail.com, mingo@redhat.com, changwoo@igalia.com Subject: Re: [PATCH 3/6] sched_ext: Make @rf optional for dispatch_to_local_dsq() Message-ID: References: <20240709212137.1199269-1-tj@kernel.org> <20240709212137.1199269-4-tj@kernel.org> <20240710114142.GY27299@noisy.programming.kicks-ass.net> 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: <20240710114142.GY27299@noisy.programming.kicks-ass.net> Hello, On Wed, Jul 10, 2024 at 01:41:42PM +0200, Peter Zijlstra wrote: ... > > Not a blocker, but would it make sense to provide some wrappers for > > rq_unpin_lock() / rq_repin_lock() to simply return if rf == NULL? Will address this part later. > There are very limited contexts where unpin is sound. I have no idea if > this is one of them or not. This is called from balance to migrate tasks across rq's, which is where the @rf for the unpin/repin is coming from. This patchset makes the same code path called from other places, e.g. ->task_woken(), where the rq lock is already unpinned. It could be that the better thing to do here is just unpinning from the balance()'s context so that the inner functions don't have to worry about lock pinning. They're always called in a context where the rq lock can be dropped after all. Thanks. -- tejun