> On Mar 5, 2025, at 2:43 AM, Juri Lelli <juri.lelli@xxxxxxxxxx> wrote: > > >> Another one is dl_task_offline_migration which gets the task from >> dl_task_timer which in turn gets it from sched_dl_entity. >> I haven’t gone through the deadline code thoroughly but I think this race >> shouldn’t exist for the offline task (2nd) case. If that is true then the fix >> could be to check in push_dl_task if the task returned by find_lock_later_rq >> is still at the head of the queue or not. > > I believe that won't work as dl_task_offline_migration() gets called in > case the replenishment timer for a task fires (to unthrottle it) and it > finds the old rq the task was running on has been offlined in the > meantime. The task is still throttled at this point and so it is not > enqueued in the dl_rq nor in the pushable task list/tree, so the check > you are adding won't work I am afraid. Maybe we can use dl_se->dl_throttled > to differentiate this different case. > Thanks Juri. I sent the fix please take a look: https://lore.kernel.org/lkml/20250307204255.60640-1-harshit@xxxxxxxxxxx/ Instead of changing find_lock_later_rq, I added the handling in the caller i.e. push_dl_task since that’s the one affected by the race. I think we don’t need to handle the other case at all as the race is not applicable for offline migration case. Let me know if this sounds fine or if I am missing something. Regards, Harshit
