Re: unable to run NFSD in container if "options sunrpc pool_mode=pernode"

[Jeff Layton <jlayton@kernel.org>]

On Fri, 2025-05-23 at 23:53 -0400, Mike Snitzer wrote:
> On Fri, May 23, 2025 at 07:09:27PM -0400, Mike Snitzer wrote:
> > On Fri, May 23, 2025 at 06:40:45PM -0400, Jeff Layton wrote:
> > > On Fri, 2025-05-23 at 18:19 -0400, Mike Snitzer wrote:
> > > > On Fri, May 23, 2025 at 02:40:17PM -0400, Jeff Layton wrote:
> > > > > On Fri, 2025-05-23 at 14:29 -0400, Mike Snitzer wrote:
> > > > > > I don't know if $SUBJECT ever worked... but with latest 6.15 or
> > > > > > nfsd-testing if I just use pool_mode=global then all is fine.
> > > > > > 
> > > > > > If pool_mode=pernode then mounting the container's NFSv3 export fails.
> > > > > > 
> > > > > > I haven't started to dig into code yet but pool_mode=pernode works
> > > > > > perfectly fine if NFSD isn't running in a container.
> > > > > > 
> > > 
> > > Oops, I went and looked and nfsd isn't running in a container on these
> > > boxes. There are some other containerized apps running on the box, but
> > > nfsd isn't running in a container.
> > 
> > OK.
> > 
> > > > I'm using nfs-utils-2.8.2.  I don't see any nfsd threads running if I
> > > > use "options sunrpc pool_mode=pernode".
> > > > 
> > > 
> > > I'll have a look soon, but if you figure it out in the meantime, let us
> > > know.
> > 
> > Will do.
> > 
> > Just the latest info I have, with sunrpc's pool_mode=pernode dd hangs
> > with this stack trace:
> 
> Turns out this pool_mode=pernode issue is a regression caused by the
> very recent nfs-utils 2.8.2 (I rebuilt EL10's nfs-utils package,
> because why not upgrade to the latest!?).
> 
> If I use EL9.5's latest nfs-utils-2.5.4-37.el8.x86_64 then sunrpc's
> pool_mode=pernode works fine.
> 
> And this issue doesn't have anything to do with running in a container
> (it seemed to be container related purely because I happened to be
> seeing the issue with an EL9.5 container that had the EL10-based
> nfs-utils 2.8.2 installed).
> 
> Steved, unfortunately I'm not sure what the problem is with the newer
> nfs-utils and setting "options sunrpc pool_mode=pernode"
> 

This is probably a kernel problem.

Newer nfs-utils uses nfsdctl to start the server, whereas the older
nfs-utils would use rpc.nfsd. nfsdctl uses the netlink interfaces to
start the server instead of /proc/fs/nfsd which rpc.nfsd uses.

If you're getting different results with the two different nfs-utils
versions then the problem is likely there. I'll take a look.
-- 
Jeff Layton <jlayton@kernel.org>