On 07/11/2020 22:28, Jens Axboe wrote: > On 11/7/20 2:54 PM, Pavel Begunkov wrote: >> On 07/11/2020 21:18, Pavel Begunkov wrote: >>> On 07/11/2020 21:16, Pavel Begunkov wrote: >>>> SQPOLL task may find sqo_task->files == NULL, so >>>> __io_sq_thread_acquire_files() would left it unset and so all the >>>> following fails, e.g. attempts to submit. Fail if sqo_task doesn't have >>>> files. >>> >>> Josef, could you try this one? >> >> Hmm, as you said it happens often... IIUC there is a drawback with >> SQPOLL -- after the creator process/thread exits most of subsequent >> requests will start failing. >> I'd say from application correctness POV such tasks should exit >> only after their SQPOLL io_urings got killed. > > I don't think there's anything wrong with that - if you submit requests > and exit before they have completed, then you by definition are not > caring about the result of them. Other threads may use it as well thinking that this is fine as they share mm, files, etc. 1. task1 create io_uring 2. clone(CLONE_FILES|CLONE_VM|...) -> task2 3. task1 exits 4. task2 continues to use io_uring -- Pavel Begunkov
