On Fri, Jan 25, 2008 at 06:55:48PM -0500, Jeff Layton wrote:
> On Fri, 25 Jan 2008 18:17:17 -0500
> "J. Bruce Fields" <[EMAIL PROTECTED]> wrote:
> 
> > From: Jeff Layton <[EMAIL PROTECTED]>
> > 
> > If we're shutting down all the nlm_hosts anyway, then it doesn't make
> > sense to allow RPC calls to linger. Allowing them to do so can mean
> > that the RPC calls can outlive the currently running lockd and can
> > lead to a use after free situation.
> > 
> > Signed-off-by: Jeff Layton <[EMAIL PROTECTED]>
> > Reviewed-by: NeilBrown <[EMAIL PROTECTED]>
> > Signed-off-by: J. Bruce Fields <[EMAIL PROTECTED]>
> > ---
> >  fs/lockd/host.c |    4 +++-
> >  1 files changed, 3 insertions(+), 1 deletions(-)
> > 
> > diff --git a/fs/lockd/host.c b/fs/lockd/host.c
> > index ebec009..76e4bf5 100644
> > --- a/fs/lockd/host.c
> > +++ b/fs/lockd/host.c
> > @@ -379,8 +379,10 @@ nlm_shutdown_hosts(void)
> >     /* First, make all hosts eligible for gc */
> >     dprintk("lockd: nuking all hosts...\n");
> >     for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH;
> > ++chain) {
> > -           hlist_for_each_entry(host, pos, chain, h_hash)
> > +           hlist_for_each_entry(host, pos, chain, h_hash) {
> >                     host->h_expires = jiffies - 1;
> > +                   rpc_killall_tasks(host->h_rpcclnt);
> > +           }
> >     }
> >  
> >     /* Then, perform a garbage collection pass */
> 
> I was doing some more testing today, and noticed that the original
> problem that this patch is intended to fix resurfaced. I think this
> patch just changes the timing on the race somehow, but I haven't tracked
> it down completely yet.

Hm.  So you're getting oopses that look like the rpc code attempting to
make calls with an rpc_client that's been freed?

> There's also another problem -- it's possible for host->h_rpcclnt to be
> NULL, and that has special meaning for rpc_killall_tasks. For now, I
> suggest that we drop this patch until I have a chance to work on it
> further.
> 
> The other related patches in this series should be OK, however.

OK!  Dropped.  Let me know what you find out.

--b.
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