On Tue, 23 Nov 2021, J. Bruce Fields wrote:
> >
> > Hm, playing with reproducer; it takes more than one mount. My simplest
> > reproducer is:
> >
> > mount -overs=3 server:/path /mnt/
> > umount /mnt/
> > mount -overs=4.0 server:/path /mnt/
> >
> > ... and the client crashes here.
>
> Also: the problem starts with the last patch ("lockd: use
> svc_set_num_threads() for thread start and stop").
That helps. It points to lockd, and so to lockd stopping.
Lockd wasn't stopping for me because I had nfsd running.
I disabled nfsd and tried again - and got the crash.
The problem is
#define svc_serv_is_pooled(serv) ((serv)->sv_ops->svo_function)
Why does the presence of a svo_function mark the serv as being
'pooled'???
That last patch gave lockd an svo_function, so when threats were
stopped, the pool was released. But as lockd doesn't create a pooled
service, the pool was never claimed. So the pool_map->npools was set
to zero even though it should have still been active.
I'll probably change svc_serv_is_pooled() to test serv->sv_nrpools, and
allow that to be zero for non-pooled services.
Thanks for your testing help,
NeilBrown
