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[72.235.129.167]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1ff58f29e0dsm130271005ad.38.2024.08.08.16.36.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Aug 2024 16:36:57 -0700 (PDT) Sender: Tejun Heo Date: Thu, 8 Aug 2024 13:36:56 -1000 From: Tejun Heo To: David Vernet Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH sched_ext/for-6.12] sched_ext: Fix unsafe list iteration in process_ddsp_deferred_locals() Message-ID: References: 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: On Wed, Aug 07, 2024 at 10:17:38AM -1000, Tejun Heo wrote: > process_ddsp_deferred_locals() executes deferred direct dispatches to the > local DSQs of remote CPUs. It iterates the tasks on > rq->scx.ddsp_deferred_locals list, removing and calling > dispatch_to_local_dsq() on each. However, the list is protected by the rq > lock that can be dropped by dispatch_to_local_dsq() temporarily, so the list > can be modified during the iteration, which can lead to oopses and other > failures. > > Fix it by popping from the head of the list instead of iterating the list. > > Signed-off-by: Tejun Heo > Fixes: 5b26f7b920f7 ("sched_ext: Allow SCX_DSQ_LOCAL_ON for direct dispatches") Applied to sched_ext/for-6.12. Thanks. -- tejun