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* Potential corner case in release 5.8
@ 2021-03-05 19:07 Ryan Sharpelletti
  2021-04-06 17:53 ` Ryan Sharpelletti
  0 siblings, 1 reply; 3+ messages in thread
From: Ryan Sharpelletti @ 2021-03-05 19:07 UTC (permalink / raw)
  To: io-uring

Hi,

I suspect there is a corner case for io_uring in release 5.8.

Can you please explain where the associated mmdrop/kthread_unuse_mm
calls for io_sq_thread_acquire_mm in io_init_req(...) are?
Specifically, what would happen if there was an error after calling
io_sq_thread_acquire_mm (for example, the -EINVAL a few lines after)?

From what I can understand, it looks like the kthread_unuse_mm and
mmput might be handled in the call to io_sq_thread_acquire_mm in
io_sq_thread. However, I am not seeing where mmdrop might be called.

Thanks,
Ryan

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: Potential corner case in release 5.8
  2021-03-05 19:07 Potential corner case in release 5.8 Ryan Sharpelletti
@ 2021-04-06 17:53 ` Ryan Sharpelletti
  2021-04-07 12:52   ` Pavel Begunkov
  0 siblings, 1 reply; 3+ messages in thread
From: Ryan Sharpelletti @ 2021-04-06 17:53 UTC (permalink / raw)
  To: io-uring; +Cc: axboe

Hi,

I am following up on the above, do you know where the associated
mmdrop might be called?

Thanks,
Ryan



On Fri, Mar 5, 2021 at 2:07 PM Ryan Sharpelletti
<[email protected]> wrote:
>
> Hi,
>
> I suspect there is a corner case for io_uring in release 5.8.
>
> Can you please explain where the associated mmdrop/kthread_unuse_mm
> calls for io_sq_thread_acquire_mm in io_init_req(...) are?
> Specifically, what would happen if there was an error after calling
> io_sq_thread_acquire_mm (for example, the -EINVAL a few lines after)?
>
> From what I can understand, it looks like the kthread_unuse_mm and
> mmput might be handled in the call to io_sq_thread_acquire_mm in
> io_sq_thread. However, I am not seeing where mmdrop might be called.
>
> Thanks,
> Ryan

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: Potential corner case in release 5.8
  2021-04-06 17:53 ` Ryan Sharpelletti
@ 2021-04-07 12:52   ` Pavel Begunkov
  0 siblings, 0 replies; 3+ messages in thread
From: Pavel Begunkov @ 2021-04-07 12:52 UTC (permalink / raw)
  To: Ryan Sharpelletti, io-uring; +Cc: axboe

On 06/04/2021 18:53, Ryan Sharpelletti wrote:
> On Fri, Mar 5, 2021 at 2:07 PM Ryan Sharpelletti
> <[email protected]> wrote:
>> I suspect there is a corner case for io_uring in release 5.8.

Did you see any fail?

>> Can you please explain where the associated mmdrop/kthread_unuse_mm
>> calls for io_sq_thread_acquire_mm in io_init_req(...) are?

Look for io_sq_thread_drop_mm(). acquire_mm shouldn't do anything
unless it's SQPOLL mode and so executed by sqpoll task.

>> Specifically, what would happen if there was an error after calling
>> io_sq_thread_acquire_mm (for example, the -EINVAL a few lines after)?

Will be cleaned by io_sq_thread().

>>
>> From what I can understand, it looks like the kthread_unuse_mm and
>> mmput might be handled in the call to io_sq_thread_acquire_mm in
>> io_sq_thread. However, I am not seeing where mmdrop might be called.


-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-04-07 12:56 UTC | newest]

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2021-03-05 19:07 Potential corner case in release 5.8 Ryan Sharpelletti
2021-04-06 17:53 ` Ryan Sharpelletti
2021-04-07 12:52   ` Pavel Begunkov

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