Re: nfsd dead loop when xfstests generic/531

J. Bruce Fields
2021-06-08T17:20:19Z

On Tue, Jun 01, 2021 at 04:55:35PM +0000, Frank van der Linden wrote:
> On Mon, May 31, 2021 at 12:59:51PM +0800, Wang Yugui wrote:
> >
> >
> > Hi,
> >
> > nfsd dead loop when xfstests generic/531
> >
> > linux kernel of nfs server: 5.10.41
> > linux kernel of nfs client: 5.10.41
> >
> >
> > nfsd dead loop when xfstests generic/531
> >
> > linux kernel of nfs server: 5.10.41
> > linux kernel of nfs client: 5.10.41
>
> This is a known issue. generic/531 opens a large number of files, causing
> the nfsd file cache code to walk a very long LRU list of open files. For
> v4, there will be a lot of long term opens (because of the OPEN call),
> and they all end up on that list.
>
> So, the basic issue is, that the nfsd file cache is a good match for
> v3 semantics, but less so for v4 semantics.
>
> I posted an experimental patch to work around the issue:
>
> https://lore.kernel.org/linux-nfs/20201020183718.14618-4-trondmy@kernel.org/T/#m869aa427f125afee2af9a89d569c6b98e12e516f
>
> The rhashtable patch has issues, so disregard that one, but the other one
> is a basic fix for this issue. It has one other issue that I noticed (refcount
> error), but that is easily fixed.
>
> I should update the patch and formally post it..

That would be great.

--b.