Commit 4beac029 authored by Nikolay Aleksandrov's avatar Nikolay Aleksandrov Committed by David S. Miller
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bonding: fix system hang due to fast igmp timer rescheduling

After commit 4aa5dee4

 ("net: convert resend IGMP to notifier event")
we try to acquire rtnl in bond_resend_igmp_join_requests but it can be
scheduled with rtnl already held (e.g. when bond_change_active_slave is
called with rtnl) causing a loop of immediate reschedules + calls because
rtnl_trylock fails each time since it's being already held.
For me this issue leads to system hangs very easy:
modprobe bonding; ifconfig bond0 up; ifenslave bond0 eth0; rmmod

The fix is to introduce a small (1 jiffy) delay which is enough for the
sections holding rtnl to finish without putting any strain on the system.
Also adjust the timer in bond_change_active_slave to be 1 jiffy, since
most of the time it's called with rtnl already held.

Signed-off-by: default avatarNikolay Aleksandrov <>
Signed-off-by: default avatarDavid S. Miller <>
parent 9ab5ec59
......@@ -723,7 +723,7 @@ static int bond_set_allmulti(struct bonding *bond, int inc)
static void bond_resend_igmp_join_requests(struct bonding *bond)
if (!rtnl_trylock()) {
queue_delayed_work(bond->wq, &bond->mcast_work, 0);
queue_delayed_work(bond->wq, &bond->mcast_work, 1);
call_netdevice_notifiers(NETDEV_RESEND_IGMP, bond->dev);
......@@ -1084,7 +1084,7 @@ void bond_change_active_slave(struct bonding *bond, struct slave *new_active)
((USES_PRIMARY(bond->params.mode) && new_active) ||
bond->params.mode == BOND_MODE_ROUNDROBIN)) {
bond->igmp_retrans = bond->params.resend_igmp;
queue_delayed_work(bond->wq, &bond->mcast_work, 0);
queue_delayed_work(bond->wq, &bond->mcast_work, 1);
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