Re: io_uring process termination/killing is not working

[Pavel Begunkov <asml.silence@gmail.com>]

On 15/08/2020 18:12, Jens Axboe wrote:
> On 8/15/20 12:45 AM, Pavel Begunkov wrote:
>> On 13/08/2020 02:32, Jens Axboe wrote:
>>> On 8/12/20 12:28 PM, Pavel Begunkov wrote:
>>>> On 12/08/2020 21:22, Pavel Begunkov wrote:
>>>>> On 12/08/2020 21:20, Pavel Begunkov wrote:
>>>>>> On 12/08/2020 21:05, Jens Axboe wrote:
>>>>>>> On 8/12/20 11:58 AM, Josef wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I have a weird issue on kernel 5.8.0/5.8.1, SIGINT even SIGKILL
>>>>>>>> doesn't work to kill this process(always state D or D+), literally I
>>>>>>>> have to terminate my VM because even the kernel can't kill the process
>>>>>>>> and no issue on 5.7.12-201, however if IOSQE_IO_LINK is not set, it
>>>>>>>> works
>>>>>>>>
>>>>>>>> I've attached a file to reproduce it
>>>>>>>> or here
>>>>>>>> https://gist.github.com/1Jo1/15cb3c63439d0c08e3589cfa98418b2c
>>>>>>>
>>>>>>> Thanks, I'll take a look at this. It's stuck in uninterruptible
>>>>>>> state, which is why you can't kill it.
>>>>>>
>>>>>> It looks like one of the hangs I've been talking about a few days ago,
>>>>>> an accept is inflight but can't be found by cancel_files() because it's
>>>>>> in a link.
>>>>>
>>>>> BTW, I described it a month ago, there were more details.
>>>>
>>>> https://lore.kernel.org/io-uring/34eb5e5a-8d37-0cae-be6c-c6ac4d85b5d4@gmail.com
>>>
>>> Yeah I think you're right. How about something like the below? That'll
>>> potentially cancel more than just the one we're looking for, but seems
>>> kind of silly to only cancel from the file table holding request and to
>>> the end.
>>
>> The bug is not poll/t-out related, IIRC my test reproduces it with
>> read(pipe)->open(). See the previously sent link.
> 
> Right, but in this context for poll, I just mean any request that has a
> poll handler armed. Not necessarily only a pure poll. The patch should
> fix your case, too.

Ok. I was thinking about sleeping in io_read(), etc. from io-wq context.
That should have the same effect.

> 
>> As mentioned, I'm going to patch that up, if you won't beat me on that.
> 
> Please test and send a fix if you find something! I'm going to ship what
> I have this weekend, but we can always add a fix on top if we need
> anything.

Sure

-- 
Pavel Begunkov