On 21/12/2020 11:00, Dmitry Kadashev wrote: > On Mon, Dec 21, 2020 at 5:35 PM Dmitry Kadashev <dkadashev@xxxxxxxxx> wrote: >> >> On Sun, Dec 20, 2020 at 7:59 AM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote: >>> >>> On 20/12/2020 00:25, Jens Axboe wrote: >>>> On 12/19/20 4:42 PM, Pavel Begunkov wrote: >>>>> On 19/12/2020 23:13, Jens Axboe wrote: >>>>>> On 12/19/20 2:54 PM, Jens Axboe wrote: >>>>>>> On 12/19/20 1:51 PM, Josef wrote: >>>>>>>>> And even more so, it's IOSQE_ASYNC on the IORING_OP_READ on an eventfd >>>>>>>>> file descriptor. You probably don't want/mean to do that as it's >>>>>>>>> pollable, I guess it's done because you just set it on all reads for the >>>>>>>>> test? >>>>>>>> >>>>>>>> yes exactly, eventfd fd is blocking, so it actually makes no sense to >>>>>>>> use IOSQE_ASYNC >>>>>>> >>>>>>> Right, and it's pollable too. >>>>>>> >>>>>>>> I just tested eventfd without the IOSQE_ASYNC flag, it seems to work >>>>>>>> in my tests, thanks a lot :) >>>>>>>> >>>>>>>>> In any case, it should of course work. This is the leftover trace when >>>>>>>>> we should be exiting, but an io-wq worker is still trying to get data >>>>>>>>> from the eventfd: >>>>>>>> >>>>>>>> interesting, btw what kind of tool do you use for kernel debugging? >>>>>>> >>>>>>> Just poking at it and thinking about it, no hidden magic I'm afraid... >>>>>> >>>>>> Josef, can you try with this added? Looks bigger than it is, most of it >>>>>> is just moving one function below another. >>>>> >>>>> Hmm, which kernel revision are you poking? Seems it doesn't match >>>>> io_uring-5.10, and for 5.11 io_uring_cancel_files() is never called with >>>>> NULL files. >>>>> >>>>> if (!files) >>>>> __io_uring_cancel_task_requests(ctx, task); >>>>> else >>>>> io_uring_cancel_files(ctx, task, files); >>>> >>>> Yeah, I think I messed up. If files == NULL, then the task is going away. >>>> So we should cancel all requests that match 'task', not just ones that >>>> match task && files. >>>> >>>> Not sure I have much more time to look into this before next week, but >>>> something like that. >>>> >>>> The problem case is the async worker being queued, long before the task >>>> is killed and the contexts go away. But from exit_files(), we're only >>>> concerned with canceling if we have inflight. Doesn't look right to me. >>> >>> In theory all that should be killed in io_ring_ctx_wait_and_kill(), >>> of course that's if the ring itself is closed. >>> >>> Guys, do you share rings between processes? Explicitly like sending >>> io_uring fd over a socket, or implicitly e.g. sharing fd tables >>> (threads), or cloning with copying fd tables (and so taking a ref >>> to a ring). >> >> We do not share rings between processes. Our rings are accessible from different >> threads (under locks), but nothing fancy. >> >>> In other words, if you kill all your io_uring applications, does it >>> go back to normal? >> >> I'm pretty sure it does not, the only fix is to reboot the box. But I'll find an >> affected box and double check just in case. > > So, I've just tried stopping everything that uses io-uring. No io_wq* processes > remained: > > $ ps ax | grep wq > 9 ? I< 0:00 [mm_percpu_wq] > 243 ? I< 0:00 [tpm_dev_wq] > 246 ? I< 0:00 [devfreq_wq] > 27922 pts/4 S+ 0:00 grep --colour=auto wq > $ > > But not a single ring (with size 1024) can be created afterwards anyway. > > Apparently the problem netty hit and this one are different? Yep, looks like it -- Pavel Begunkov
