Re: [ipv6] a088d1d73a: WARNING:at_net/mac80211/agg-tx.c:#ieee80211_start_tx_ba_cb[mac80211]

[Linus LÃssing]

On Wed, Feb 22, 2017 at 10:03:02AM +0800, kernel test robot wrote:
> 
> FYI, we noticed the following commit:
> 
> commit: a088d1d73a4bcfd7bc482f8d08375b9b665dc3e5 ("ipv6: Fix IPv6 packet loss in scenarios involving roaming + snooping switches")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> 
> in testcase: hwsim
> with following parameters:
> 
> 	group: hwsim-01
[...]
> kern  :warn  : [  146.568070] WARNING: CPU: 12 PID: 669 at net/mac80211/agg-tx.c:770 ieee80211_start_tx_ba_cb+0x139/0x150 [mac80211]
[...]
> kern  :warn  : [  146.568114] CPU: 12 PID: 669 Comm: kworker/u256:1 Not tainted 4.10.0-rc6-00104-ga088d1d #1
> kern  :warn  : [  146.568115] Hardware name: Intel Corporation LH Pass/S4600LH...., BIOS SE5C600.86B.99.02.1047.032320122259 03/23/2012
> kern  :warn  : [  146.568127] Workqueue: phy0 ieee80211_iface_work [mac80211]
> kern  :warn  : [  146.568128] Call Trace:
> kern  :warn  : [  146.568141]  dump_stack+0x63/0x8a
> kern  :warn  : [  146.568146]  __warn+0xcb/0xf0
> kern  :warn  : [  146.568147]  warn_slowpath_null+0x1d/0x20
> kern  :warn  : [  146.568156]  ieee80211_start_tx_ba_cb+0x139/0x150 [mac80211]
> kern  :warn  : [  146.568166]  ieee80211_iface_work+0x266/0x470 [mac80211]
> kern  :warn  : [  146.568180]  process_one_work+0x1a3/0x480
> kern  :warn  : [  146.568182]  worker_thread+0x4e/0x4d0
> kern  :warn  : [  146.568185]  kthread+0x10c/0x140
> kern  :warn  : [  146.568187]  ? process_one_work+0x480/0x480
> kern  :warn  : [  146.568187]  ? kthread_create_on_node+0x40/0x40
> kern  :warn  : [  146.568195]  ret_from_fork+0x2c/0x40
> kern  :warn  : [  146.568197] ---[ end trace 0e4afc24db5dbafa ]---

Unfortunately, I wasn't able to reproduce this issue with the
plain mac80211-hwsim test suite yet. The according test runs successfully
in my VMs here...

To me, it looks like the WARN_ON() could be triggered by a race condition
in mac80211 or mac80211-hwsim, too. I'm going to forward this to and
discuss this further on the wireless mailing list.

Thanks for the notification, Xiaolong!

Regards, Linus