On Wed, Nov 01, 2017 at 01:10:36PM +0300, Vasily Averin wrote: > > > On 2017-11-01 00:18, J. Bruce Fields wrote: > > On Tue, Oct 31, 2017 at 10:31:35AM +0300, Vasily Averin wrote: > >> On 2017-10-30 21:29, Jeff Layton wrote: > >>> Vasily, would this patch fix the panic you're seeing? We may still > >>> need to do something saner here, but this seems like it should at > >>> least prevent a double list_add. > >> > >> Jeff, I think your patch is wrong. > >> > >> Double list_add is not a real problem, it is just a marker of its presence. > >> It's great that such marker exist, it allows to detect the problems. > > Jeff, what do you about about following hunk ? > > --- a/fs/nfs_common/grace.c > +++ b/fs/nfs_common/grace.c > @@ -30,7 +30,11 @@ locks_start_grace(struct net *net, struct lock_manager *lm) > struct list_head *grace_list = net_generic(net, grace_net_id); > > spin_lock(&grace_lock); > - list_add(&lm->list, grace_list); > + if (list_empty(&lm->list)) > + list_add(&lm->list, grace_list); > + else > + WARN(1, "double list_add attempt detected in %s %p\n", > + (net == &init_net) ? "init_net" : "net", net); > spin_unlock(&grace_lock); > } > EXPORT_SYMBOL_GPL(locks_start_grace); > > It allows to avoid list corruption and panic > but will report about detected problem > > [ 344.722040] double list_add attempt detected in init_net ffffffffa4fd9800 > [ 344.722108] ------------[ cut here ]------------ > [ 344.722142] WARNING: CPU: 3 PID: 1505 at fs/nfs_common/grace.c:37 locks_start_grace+0xa2/0xb0 [grace] > > > I think by same way we can also detect and disarm lost delayed_work on stop of network namespace. > (in lockd_exit_net) Jeff, were you planning to resend this? --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
