Re: (subset) [PATCH 00/11] remove aux CQE caches

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

On 3/17/24 21:32, Jens Axboe wrote:
> On 3/17/24 3:29 PM, Pavel Begunkov wrote:
>> On 3/17/24 21:24, Jens Axboe wrote:
>>> On 3/17/24 2:55 PM, Pavel Begunkov wrote:
>>>> On 3/16/24 13:56, Ming Lei wrote:
>>>>> On Sat, Mar 16, 2024 at 01:27:17PM +0000, Pavel Begunkov wrote:
>>>>>> On 3/16/24 11:52, Ming Lei wrote:
>>>>>>> On Fri, Mar 15, 2024 at 04:53:21PM -0600, Jens Axboe wrote:
>>>>>
>>>>> ...
>>>>>
>>>>>>> The following two error can be triggered with this patchset
>>>>>>> when running some ublk stress test(io vs. deletion). And not see
>>>>>>> such failures after reverting the 11 patches.
>>>>>>
>>>>>> I suppose it's with the fix from yesterday. How can I
>>>>>> reproduce it, blktests?
>>>>>
>>>>> Yeah, it needs yesterday's fix.
>>>>>
>>>>> You may need to run this test multiple times for triggering the problem:
>>>>
>>>> Thanks for all the testing. I've tried it, all ublk/generic tests hang
>>>> in userspace waiting for CQEs but no complaints from the kernel.
>>>> However, it seems the branch is buggy even without my patches, I
>>>> consistently (5-15 minutes of running in a slow VM) hit page underflow
>>>> by running liburing tests. Not sure what is that yet, but might also
>>>> be the reason.
>>>
>>> Hmm odd, there's nothing in there but your series and then the
>>> io_uring-6.9 bits pulled in. Maybe it hit an unfortunate point in the
>>> merge window -git cycle? Does it happen with io_uring-6.9 as well? I
>>> haven't seen anything odd.
>>
>> Need to test io_uring-6.9. I actually checked the branch twice, both
>> with the issue, and by full recompilation and config prompts I assumed
>> you pulled something in between (maybe not).
>>
>> And yeah, I can't confirm it's specifically an io_uring bug, the
>> stack trace is usually some unmap or task exit, sometimes it only
>> shows when you try to shutdown the VM after tests.
> 
> Funky. I just ran a bunch of loops of liburing tests and Ming's ublksrv
> test case as well on io_uring-6.9 and it all worked fine. Trying
> liburing tests on for-6.10/io_uring as well now, but didn't see anything
> the other times I ran it. In any case, once you repost I'll rebase and
> then let's see if it hits again.
> 
> Did you run with KASAN enabled

Yes, it's a debug kernel, full on KASANs, lockdeps and so

-- 
Pavel Begunkov