It should be Qdisc's busylock in dev_queue_xmit function. I have seen the issue in kernel version is 3.10.87 vanilla.
On Wed, Jun 13, 2018 at 12:21 PM, Pravin Shelar <[email protected]> wrote: > On Tue, Jun 12, 2018 at 10:58 PM, Neelakantam Gaddam > <[email protected]> wrote: > > Hi Pravin, > > > > I have seen the below crash. > > > > [<ffffffff80864cd4>] show_stack+0x6c/0xf8 > > > > [<ffffffff80ad1628>] do_raw_spin_lock+0x168/0x170 > > > > [<ffffffff80bf7b1c>] dev_queue_xmit+0x43c/0x470 > > > > [<ffffffff80c32c08>] ip_finish_output+0x250/0x490 > > > > [<ffffffffc0115664>] rpl_iptunnel_xmit+0x134/0x218 [openvswitch] > > > > [<ffffffffc0120f28>] rpl_vxlan_xmit+0x430/0x538 [openvswitch] > > > > [<ffffffffc00f9de0>] do_execute_actions+0x18f8/0x19e8 [openvswitch] > > > > [<ffffffffc00fa2b0>] ovs_execute_actions+0x90/0x208 [openvswitch] > > > > [<ffffffffc0101860>] ovs_dp_process_packet+0xb0/0x1a8 [openvswitch] > > > > [<ffffffffc010c5d8>] ovs_vport_receive+0x78/0x130 [openvswitch] > > > > [<ffffffffc010ce6c>] internal_dev_xmit+0x34/0x98 [openvswitch] > > > > [<ffffffff80bf74d0>] dev_hard_start_xmit+0x2e8/0x4f8 > > > > [<ffffffff80c10e48>] sch_direct_xmit+0xf0/0x238 > > > > [<ffffffff80bf78b8>] dev_queue_xmit+0x1d8/0x470 > > > > [<ffffffff80c5ffe4>] arp_process+0x614/0x628 > > > > [<ffffffff80bf0cb0>] __netif_receive_skb_core+0x2e8/0x5d8 > > > > [<ffffffff80bf4770>] process_backlog+0xc0/0x1b0 > > > > [<ffffffff80bf501c>] net_rx_action+0x154/0x240 > > > > [<ffffffff8088d130>] __do_softirq+0x1d0/0x218 > > > > [<ffffffff8088d240>] do_softirq+0x68/0x70 > > > > [<ffffffff8088d3a0>] local_bh_enable+0xa8/0xb0 > > > > [<ffffffff80bf5c88>] netif_rx_ni+0x20/0x30 > > > > > > > > > > I have spent some time in investigation and found that crash is because > of > > spinlock recursion in dev_queue_xmit function. > > The packet path traced is : netif_rx->arp->dev_queue_xmit(internal > > port)->vxlan_xmit->dev_queue_xmit(internal port). > > > > Which spin-lock is it? I am surprised to see a lock taken in fast > path. Can you also share kernel version? > > > The macro (XMIT_RECURSION_LIMIT) is defined as 10. This limit wont > prevent > > the crash since the recursion is 2 only for my configuration. > > right, The recursion limit is to avoid stack overflow. > > > > > > > > > On Wed, Jun 13, 2018 at 4:11 AM, Pravin Shelar <[email protected]> wrote: > >> > >> On Tue, Jun 12, 2018 at 10:11 AM, Neelakantam Gaddam > >> <[email protected]> wrote: > >> > > >> > Hi Pravin, > >> > > >> > The below configuration is causing the spinlock recursion issue. > >> > > >> > I am able to see the issue with below configuration. > >> > > >> > > >> > > >> > ovs-vsctl add-br br0 > >> > > >> > ovs-vsctl add-bond br0 bond0 p1p1 p1p2 > >> > > >> > ovs-vsctl set port bond0 lacp=active bond_mode=balance-tcp > >> > > >> > ifconfig br0 100.0.0.1 up > >> > > >> > ovs-vsctl add-port br0 veth0 > >> > > >> > ovs-vsctl add-port br0 vx0 -- set interface vx0 type=vxlan > >> > options:local_ip=100.0.0.1 options:remote_ip=100.0.0.2 option:key=flow > >> > > >> > > >> > > >> > ovs-ofctl add-flow br0 "table=0, priority=1, cookie=100, tun_id=100, > >> > in_port=4, action=output:3" > >> > > >> > ovs-ofctl add-flow br0 "table=0, priority=1, cookie=100, in_port=3, > >> > actions=set_field:100->tun_id output:4" > >> > > >> > > >> > > >> > The same bridge br0 is being used as the local interface for vxlan > >> > tunnel. Even though this configuration is invalid, we should not see > the > >> > kernel crash. > >> > > >> > >> I agree this should not cause crash. > >> Can you post the crash or investigate why it is crashing I think such > >> configuration would hit the networking stack recursion limit > >> (XMIT_RECURSION_LIMIT) and then the packet would be dropped. I am not > >> sure which spinlock recursion issue you are referring to. > >> > >> > >> > > >> > > >> > > >> > > >> > On Tue, Jun 12, 2018 at 11:55 AM, Pravin Shelar <[email protected]> > wrote: > >> >> > >> >> > >> >> > >> >> On Tue, May 22, 2018 at 10:16 PM, Neelakantam Gaddam > >> >> <[email protected]> wrote: > >> >>> > >> >>> This patch fixes the kernel soft lockup issue with vxlan > configuration > >> >>> where the tunneled packet is sent on the same bridge where vxlan > port > >> >>> is > >> >>> attched to. It detects the loop in vxlan xmit functionb and drops if > >> >>> loop is > >> >>> detected. > >> >>> > >> >>> Signed-off-by: Neelakantam Gaddam <[email protected]> > >> >>> --- > >> >>> datapath/linux/compat/vxlan.c | 6 ++++-- > >> >>> 1 file changed, 4 insertions(+), 2 deletions(-) > >> >>> > >> >>> diff --git a/datapath/linux/compat/vxlan.c > >> >>> b/datapath/linux/compat/vxlan.c > >> >>> index 287dad2..00562fa 100644 > >> >>> --- a/datapath/linux/compat/vxlan.c > >> >>> +++ b/datapath/linux/compat/vxlan.c > >> >>> @@ -1115,7 +1115,8 @@ static void vxlan_xmit_one(struct sk_buff > *skb, > >> >>> struct net_device *dev, > >> >>> goto tx_error; > >> >>> } > >> >>> > >> >>> - if (rt->dst.dev == dev) { > >> >>> + if ((rt->dst.dev == dev) || > >> >>> + (OVS_CB(skb)->input_vport->dev == > >> >>> rt->dst.dev)) { > >> >> > >> >> > >> >> I am not sure which case the OVS_CB(skb)->input_vport->dev is not > same > >> >> as the dev when there is recursion. Can you explain how to reproduce > it? > >> >> > >> > > >> > > >> > > >> > -- > >> > Thanks & Regards > >> > Neelakantam Gaddam > > > > > > > > > > -- > > Thanks & Regards > > Neelakantam Gaddam > -- Thanks & Regards Neelakantam Gaddam _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
