Messages in this thread | | | Subject | Re: lockdep: adding bonding device triggers warning | From | Arjan van de Ven <> | Date | Fri, 18 Aug 2006 14:46:28 +0200 |
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On Tue, 2006-08-15 at 14:11 -0400, Bill Nottingham wrote: > 2.6.17-1.2564.fc6 is 2.6.18rc4+. > > Happened with 'echo "+bond0" > /sys/class/net/bonding_masters' > > bonding: bond0 is being created... > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.17-1.2564.fc6 #1 > ------------------------------------------------------- > bash/9497 is trying to acquire lock: > (rtnl_mutex){--..}, at: [<c0612860>] mutex_lock+0x21/0x24 > > but task is already holding lock: > (&bonding_rwsem){----}, at: [<f8c332e0>] bonding_store_bonds+0x28/0x1c6 [bonding] > > which lock already depends on the new lock.
looks like a real deadlock:
SIOCSIFNAME ioctl takes rtnl_lock() then calls dev_ifsioc which calls dev_change_name which calls the netdev_chain notifier... which ends up calling bond_event_changename() which does: down_write(&(bonding_rwsem));
on the other hand, bonding_store_bonds() does down_write(&(bonding_rwsem)); then calls bond_create() which does: int bond_create(char *name, struct bond_params *params, struct bonding **newbond) { struct net_device *bond_dev; int res;
rtnl_lock();
since these both are global locks and not per device locks, this really does look like an AB-BA deadlock to me....
-- if you want to mail me at work (you don't), use arjan (at) linux.intel.com
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