On Wed, Nov 02, 2022 at 07:44:57AM -0400, Steven Rostedt wrote: > > before starting throwing some patch into the the air I would like to align with you the approach we should take here. > > > > my suggestion here : > > - ftrace infra should verify no migration happen (end and start happens on same CPU) in case not we will throw warning for the issue . > > The scheduler should have. On entering the ring buffer code > ring_buffer_lock_reserver() it disables preemption and does not > re-enable it until ring_buffer_unlock_commit(). > > The only way to migrate is if you re-enable preemption. WHICH IS A > BUG! So what on earth did that? I'm guessing some driver's query_pkey op, but AFAIK we don't have any explicit pre-emption reenablements in the code - unless it is sneaky.. Leonid what driver are you testing? Jason
