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

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

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.

>> I'll repost it with the locking fix for reference, would make more
>> sense retesting ublk after figuring out what's up with the branch.
> 
> Yep if you repost it with the fix, I'll rebase for-6.10/io_uring.
> 

-- 
Pavel Begunkov