On 2019-09-24 10:47:36 [-0500], Scott Wood wrote: > When the stop machine finishes it will do a wake_up_process() via > complete(). Since this does not pass WF_LOCK_SLEEPER, saved_state will be > cleared, and you'll have TASK_RUNNING when you get to other_func() and > schedule(), regardless of whether CPU1 sends wake_up() -- so this change > doesn't actually accomplish anything. True, I completely missed that part. > While as noted in the other thread I don't think these spurious wakeups are > a huge problem, we could avoid them by doing stop_one_cpu_nowait() and then > schedule() without messing with task state. Since we're stopping our own > cpu, it should be guaranteed that the stopper has finished by the time we > exit schedule(). I remember loosing a state can be a problem. Lets say it is not "just" TASK_UNINTERRUPTIBLE -> TASK_RUNNING which sounds harmless but it is __TASK_TRACED and you lose it as part of unlocking siglock. > -Scott Sebastian
