| Message ID | 20101207194330.GA22608@noc.grnet.gr |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
Thanks for the patch. Can reproduce it on a vm here, I'll verify it when have access to some X.25 networks tomorrow. 2010/12/8 Apollon Oikonomopoulos <apollon@noc.grnet.gr>: > Hello, > > We came across this bug when we accidentally loaded and unloaded the x25 > kernel module on a host with KVM virtual machines. All subsequent > attempts to stop a KVM instance resulted in the KVM process entering D > state. Reproducing this behaviour can be done in the following way: > > 1. modprobe x25 > 2. tunctl && ifconfig tap0 up > 3. rmmod x25 > 4. tunctl -d tap0 (hangs) > > A patch follows - we don't use X.25 ourselves so I'm not sure it won't > panic someone's system. > > Regards, > Apollon > > PS: I am not subscribed to the list, so please copy any replies to my > address. Thanks! > ---- > x25 does not decrement the network device reference counts on module unload. > Thus unregistering any pre-existing interface after unloading the x25 module > hangs and results in > > unregister_netdevice: waiting for tap0 to become free. Usage count = 1 > > This patch decrements the reference counts of all interfaces in x25_link_free, > the way it is already done in x25_link_device_down for NETDEV_DOWN events. > > Signed-off-by: Apollon Oikonomopoulos <apollon@noc.grnet.gr> > --- > net/x25/x25_link.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/net/x25/x25_link.c b/net/x25/x25_link.c > index 73e7b95..b25c646 100644 > --- a/net/x25/x25_link.c > +++ b/net/x25/x25_link.c > @@ -394,6 +394,7 @@ void __exit x25_link_free(void) > list_for_each_safe(entry, tmp, &x25_neigh_list) { > nb = list_entry(entry, struct x25_neigh, node); > __x25_remove_neigh(nb); > + dev_put(nb->dev); > } > write_unlock_bh(&x25_neigh_list_lock); > } > -- > 1.7.1 > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Apollon Oikonomopoulos <apollon@noc.grnet.gr> Date: Tue, 7 Dec 2010 21:43:30 +0200 > x25 does not decrement the network device reference counts on module unload. > Thus unregistering any pre-existing interface after unloading the x25 module > hangs and results in > > unregister_netdevice: waiting for tap0 to become free. Usage count = 1 > > This patch decrements the reference counts of all interfaces in x25_link_free, > the way it is already done in x25_link_device_down for NETDEV_DOWN events. > > Signed-off-by: Apollon Oikonomopoulos <apollon@noc.grnet.gr> Applied and queued up for -stable, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/x25/x25_link.c b/net/x25/x25_link.c index 73e7b95..b25c646 100644 --- a/net/x25/x25_link.c +++ b/net/x25/x25_link.c @@ -394,6 +394,7 @@ void __exit x25_link_free(void) list_for_each_safe(entry, tmp, &x25_neigh_list) { nb = list_entry(entry, struct x25_neigh, node); __x25_remove_neigh(nb); + dev_put(nb->dev); } write_unlock_bh(&x25_neigh_list_lock); }
Hello, We came across this bug when we accidentally loaded and unloaded the x25 kernel module on a host with KVM virtual machines. All subsequent attempts to stop a KVM instance resulted in the KVM process entering D state. Reproducing this behaviour can be done in the following way: 1. modprobe x25 2. tunctl && ifconfig tap0 up 3. rmmod x25 4. tunctl -d tap0 (hangs) A patch follows - we don't use X.25 ourselves so I'm not sure it won't panic someone's system. Regards, Apollon PS: I am not subscribed to the list, so please copy any replies to my address. Thanks! ---- x25 does not decrement the network device reference counts on module unload. Thus unregistering any pre-existing interface after unloading the x25 module hangs and results in unregister_netdevice: waiting for tap0 to become free. Usage count = 1 This patch decrements the reference counts of all interfaces in x25_link_free, the way it is already done in x25_link_device_down for NETDEV_DOWN events. Signed-off-by: Apollon Oikonomopoulos <apollon@noc.grnet.gr> --- net/x25/x25_link.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html