diff mbox

[net-next,v3] bonding: fix system hang due to fast igmp timer rescheduling

Message ID 1375350702-7777-1-git-send-email-nikolay@redhat.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Nikolay Aleksandrov Aug. 1, 2013, 9:51 a.m. UTC 
From: "Nikolay Aleksandrov" <nikolay@redhat.com>

After commit 4aa5dee4d9 ("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
bonding;

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: Nikolay Aleksandrov <nikolay@redhat.com>
---
v3: learn to spell my name :-)
v2: adjust bond_change_active_slave's mcast_work delay to 1 jiffy because
it's called with rtnl held most of the time as Jay suggested

 drivers/net/bonding/bond_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

David Miller Aug. 1, 2013, 10:53 p.m. UTC | #1 
From: Nikolay Aleksandrov <nikolay@redhat.com>
Date: Thu,  1 Aug 2013 11:51:42 +0200

> From: "Nikolay Aleksandrov" <nikolay@redhat.com>
> 
> After commit 4aa5dee4d9 ("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
> bonding;
> 
> 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: Nikolay Aleksandrov <nikolay@redhat.com>

Applied, 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 mbox

Patch

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index da3af63..bc3578e 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -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);
 		return;
 	}
 	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);
 	}
 }