Re: [PATCH net-next] net: vrf: Add IFF_NO_QUEUE flag

[David Miller]

From: David Ahern 
Date: Wed, 8 Jun 2016 19:31:51 -0600

> On 6/8/16 1:08 PM, David Ahern wrote:
>> Getting the following splat with ping in a VRF:
> 
> ...
> 
>> Fix by adding the IFF_NO_QUEUE flag for VRF devices.
>>
>> Fixes: f9eb8aea2a1e ("net_sched: transform qdisc running bit into a
>> seqcount")
>> Signed-off-by: David Ahern 
>> ---
>>  drivers/net/vrf.c | 2 ++
>>  1 file changed, 2 insertions(+)
> 
> Dave: drop this one. I'll resubmit a flags + features update after
> Eric resolves the lock issue.

Ok.

Re: [PATCH net-next] net: vrf: Add IFF_NO_QUEUE flag

[David Ahern]

On 6/8/16 1:08 PM, David Ahern wrote:

Getting the following splat with ping in a VRF:


...


Fix by adding the IFF_NO_QUEUE flag for VRF devices.

Fixes: f9eb8aea2a1e ("net_sched: transform qdisc running bit into a seqcount")
Signed-off-by: David Ahern 
---
 drivers/net/vrf.c | 2 ++
 1 file changed, 2 insertions(+)


Dave: drop this one. I'll resubmit a flags + features update after Eric 
resolves the lock issue.

[PATCH net-next] net: vrf: Add IFF_NO_QUEUE flag

[David Ahern]

Getting the following splat with ping in a VRF:

[   49.036323] ==
[   49.038300] [ INFO: possible circular locking dependency detected ]
[   49.040313] 4.7.0-rc1+ #252 Not tainted
[   49.041502] ---
[   49.043518] ping/2143 is trying to acquire lock:
[   49.044999]  (&(>lock)->rlock#3){+.-...}, at: [] 
__dev_queue_xmit+0x3d3/0x751
[   49.048107]
[   49.048107] but task is already holding lock:
[   49.049844]  (dev->qdisc_running_key ?: _running_key){+.-...}, at: 
[] __dev_queue_xmit+0x428/0x751
[   49.052783]
[   49.052783] which lock already depends on the new lock.
[   49.052783]
[   49.054455]
[   49.054455] the existing dependency chain (in reverse order) is:
[   49.055894]
-> #1 (dev->qdisc_running_key ?: _running_key){+.-...}:
[   49.057531][] __lock_acquire+0x5e4/0x690
[   49.058924][] lock_acquire+0x140/0x1d8
[   49.060271][] write_seqcount_begin+0x21/0x24
[   49.061741][] __dev_queue_xmit+0x428/0x751
[   49.062936][] dev_queue_xmit+0xb/0xd
[   49.064258][] neigh_resolve_output+0x113/0x12e
[   49.065767][] ip6_finish_output2+0x39b/0x3ee
[   49.067212][] ip6_finish_output+0x96/0x9d
[   49.068568][] ip6_output+0x80/0xe9
[   49.069789][] dst_output+0x4f/0x56
[   49.070824][] mld_sendpack+0x17e/0x1fd
[   49.071964][] mld_ifc_timer_expire+0x1ea/0x21e
[   49.073407][] call_timer_fn+0x120/0x303
[   49.074551][] run_timer_softirq+0x1ae/0x1d8
[   49.075399][] __do_softirq+0x1c3/0x451
[   49.076217][] irq_exit+0x40/0x94
[   49.076945][] smp_apic_timer_interrupt+0x29/0x34
[   49.077849][] apic_timer_interrupt+0x8c/0xa0
[   49.078719][] default_idle+0x1f/0x32
[   49.079462][] arch_cpu_idle+0xa/0xc
[   49.080191][] default_idle_call+0x1e/0x20
[   49.080989][] cpu_startup_entry+0x136/0x1ee
[   49.081805][] rest_init+0x12b/0x131
[   49.082551][] start_kernel+0x3da/0x3e7
[   49.083317][] x86_64_start_reservations+0x2f/0x31
[   49.084192][] x86_64_start_kernel+0x12d/0x13a
[   49.085025]
-> #0 (&(>lock)->rlock#3){+.-...}:
[   49.085749][] validate_chain.isra.37+0x7c8/0xa5b
[   49.086631][] __lock_acquire+0x5e4/0x690
[   49.087427][] lock_acquire+0x140/0x1d8
[   49.088194][] _raw_spin_lock+0x2f/0x65
[   49.088961][] __dev_queue_xmit+0x3d3/0x751
[   49.089771][] dev_queue_xmit+0xb/0xd
[   49.090534][] arp_xmit+0x32/0x7e
[   49.091238][] arp_send_dst+0x3c/0x42
[   49.091972][] arp_solicit+0x27b/0x28e
[   49.092719][] neigh_probe+0x4a/0x5e
[   49.093448][] __neigh_event_send+0x1d0/0x21b
[   49.094305][] neigh_event_send+0x2b/0x2d
[   49.095080][] neigh_resolve_output+0x18/0x12e
[   49.095908][] ip_finish_output2+0x3c0/0x41c
[   49.096716][] ip_finish_output+0x132/0x13e
[   49.097517][] NF_HOOK_COND.constprop.43+0x21/0x8a
[   49.098408][] ip_output+0x65/0x6a
[   49.099131][] dst_output+0x2b/0x30
[   49.099848][] ip_local_out+0x2a/0x31
[   49.100580][] vrf_xmit+0x149/0x28c
[   49.101294][] dev_hard_start_xmit+0x154/0x337
[   49.102169][] sch_direct_xmit+0x98/0x16c
[   49.102948][] __dev_queue_xmit+0x453/0x751
[   49.103747][] dev_queue_xmit+0xb/0xd
[   49.104480][] neigh_resolve_output+0x113/0x12e
[   49.105322][] dst_neigh_output.isra.18+0x13b/0x148
[   49.106204][] vrf_finish_output+0x104/0x139
[   49.107044][] vrf_output+0x5c/0xc1
[   49.107755][] dst_output+0x2b/0x30
[   49.108472][] ip_local_out+0x2a/0x31
[   49.109211][] ip_send_skb+0x14/0x38
[   49.109941][] ip_push_pending_frames+0x2e/0x31
[   49.110792][] raw_sendmsg+0x788/0x9d2
[   49.111543][] inet_sendmsg+0x35/0x5c
[   49.112283][] sock_sendmsg_nosec+0x12/0x1d
[   49.113079][] ___sys_sendmsg+0x1b1/0x21f
[   49.113851][] __sys_sendmsg+0x40/0x5e
[   49.114609][] SyS_sendmsg+0x14/0x16
[   49.115345][] entry_SYSCALL_64_fastpath+0x1f/0xbd
[   49.116221]
[   49.116221] other info that might help us debug this:
[   49.116221]
[   49.117198]  Possible unsafe locking scenario:
[   49.117198]
[   49.117926]CPU0CPU1
[   49.118503]
[   49.119059]   lock(dev->qdisc_running_key ?: _running_key);
[   49.119839]lock(&(>lock)->rlock#3);
[   49.120722] lock(dev->qdisc_running_key ?: _running_key);
[   49.121800]   lock(&(>lock)->rlock#3);
[   49.122396]
[   49.122396]  *** DEADLOCK ***
[   49.122396]
[   49.123134] 6 locks held by ping/2143:
[   49.123604]  #0:  (sk_lock-AF_INET){+.+.+.}, at: [] 
raw_sendmsg+0x729/0x9d2
[   49.124749]  #1:  (rcu_read_lock_bh){..},