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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e On 10/19/26 06:08, Frederic Weisbecker wrote: > Between CPUHP_TEARDOWN_CPU and CPUHP_AP_OFFLINE, stop_machine executes > all the teardown callbacks while stopping all CPUs in the system. This > doesn't mix-up well with running RT or isolated tasks. > > In order to transition smoothly from global stop_machine to finer > grained synchronization between teardown callbacks and the other CPUs, > a new stop machine post function has been introduced to be executed > after the main one with IRQs still disabled while other CPUs can exit > stop_machine(). > > It *looks ok* to disable the cache readahead globally while the other > CPUs are running. Yes I think it is safe given that b15_rac_dying_cpu() will run on the dying CPU and any CPU that is left will basically re-enable the RAC afterwards if necessary in b15_rac_dead_cpu(). The hardware to test this is quite ancient, but if you give me a test case to exercise, I can give it a spin. Thank you Frederic! -- Florian