io_uring: remove poll entry from list when canceling all
When the ring is exiting, as part of the shutdown, poll requests are removed. But io_poll_remove_all() does not remove entries when finding them, and since completions are done out-of-band, we can find and remove the same entry multiple times. We do guard the poll execution by poll ownership, but that does not exclude us from reissuing a new one once the previous removal ownership goes away. This can race with poll execution as well, where we then end up seeing req->apoll be NULL because a previous task_work requeue finished the request. Remove the poll entry when we find it and get ownership of it. This prevents multiple invocations from finding it. Fixes: aa43477b ("io_uring: poll rework") Reported-by:Dylan Yudaken <dylany@fb.com> Signed-off-by: