Re: io_uring process termination/killing is not working

Jens Axboe
2020-08-15T21:56:33Z

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.

> 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.

--
Jens Axboe