Re: [PATCH 1/1] Revert "RDMA/rxe: Add workqueue support for rxe tasks"

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Oct 05, 2023 at 05:25:29PM +0800, Zhu Yanjun wrote:
> 在 2023/10/5 2:38, Jason Gunthorpe 写道:
> > On Wed, Oct 04, 2023 at 10:43:20AM -0700, Bart Van Assche wrote:
> > 
> > > Thank you for having reported this. I'm OK with integrating the
> > > above change in my patch. However, code changes must be
> > > motivated. Do you perhaps have an explanation of why WQ_HIGHPRI
> > > makes the issue disappear that you observed?
> > 
> > I think it is clear there are locking bugs in all this, so it is not
> > surprising that changing the scheduling behavior can make locking bugs
> > hide
> > 
> > Jason
> 
> With the flag WQ_HIGHPRI, an ordered workqueue with high priority is
> allocated. With this workqueue, to now, the test has run for several days.
> And the problem did not appear. So to my test environment, this problem
> seems fixed with the above commit.
> 
> I doubt, without the flag WQ_HIGHPRI, the workqueue is allocated with normal
> priority. The work item in this workqueue is more likely preempted than high
> priority work queue.

Which is why it shows there are locking problems in this code.

Jason