Messages in this thread |  | | Date | Mon, 08 Dec 2025 11:15:14 +0000 | | Subject | Re: [RFC][PATCH] sched/ext: Avoid null ptr traversal when ->put_prev_task() is called with NULL next | | From | Kuba Piecuch <> |
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On Mon Dec 8, 2025 at 10:10 AM UTC, Kuba Piecuch wrote: > It looks like it's impossible for an outside observer holding a CPU's rq lock > to observe a task that is running on that CPU and isn't queued, i.e. > 'running' implies 'queued' (I'm new to the scheduler so I may be wrong here).
A task that blocks in __schedule() can drop the rq lock while picking the next task, which is after try_to_block_task() dequeues prev. So it's very much possible for a task on another CPU to grab the rq lock and observe prev as dequeued but still running.
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