Re: Flush warning

Jason Gunthorpe
2017-08-09T16:27:49Z

On Wed, Aug 09, 2017 at 11:21:38AM -0500, Steve Wise wrote:

> > I don't know. I read the workqueue doc on WQ_MEM_RECLAIM, but I don't know
> > how
> > to tell if iw_cm needs this or not. Can you give me an example of a workqueue
> > that _does_ need WQ_MEM_RECLAIM? I _think_ it means your workqueue is
> > required
> > to run something that would get triggered by the oom OS code, but I don't know
> > if that would include rdma CMs or not...
>
> Many of the workqueues in infiniband/core use WQ_MEM_RECLAIM: cma, iwcm, mad,
> multicast, sa_query, and ucma.
>
> Hey Sean, do you have any insight into whether the CMA modules really need
> WQ_MEM_RECLAIM for their workqueues?
>
> Does anyone else know?

Consider that the ib_core can be used to back storage. Ie consider a
situation where iSER/NFS/SRP needs to reconnect to respond to kernel
paging/reclaim.

On the surface it seems reasonable to me that these are on a reclaim
path?

Jason