[LEDE-DEV] stall/hang in netifd on LEDE r1318 on Linksys WRT1900AC V1

[pat]

Dear LEDE devs,

There doesn’t appear to be an LEDE forum yet, else I’d post it on the forum.  So I’m hoping someone on the mail list has a suggestion here.

I’ve been running a build of OpenWRT DD R49195 since earlier this year.
I thought I’d try to move to LEDE.

To that end, I’ve just built an image based on LEDE r1318 for a Linksys WRT1900AC V1 (aka mamba).
The build completed successfully, and the image appears to have flashed successfully.
Upon booting, the boot process stalls/hangs.  I see the following in a serial/tty console;

.	
…
….
[   16.641909] device eth0 entered promiscuous mode
[   16.649345] IPv6: ADDRCONF(NETDEV_UP): br-lan: link is not ready
[   76.692269] INFO: rcu_sched self-detected stall on CPU
[   76.697461]  1-...: (6000 ticks this GP) idle=4b7/140000000000001/0 softirq=902/919 fqs=5980 
[   76.702321] INFO: rcu_sched detected stalls on CPUs/tasks:
[   76.702341]  1-...: (6000 ticks this GP) idle=4b7/140000000000001/0 softirq=902/919 fqs=5980 
[   76.702352]  (detected by 0, t=6002 jiffies, g=111, c=110, q=990)
[   76.702356] Task dump for CPU 1:
[   76.702368] netifd          R running      0  1106      1 0x00000002
[   76.702401] [<c00101ec>] (__schedule) from [<c00da48c>] (SyS_ioctl+0x34/0x5c)
[   76.702418] [<c00da48c>] (SyS_ioctl) from [<c0009c80>] (ret_fast_syscall+0x0/0x3c)
[   76.750523]   (t=6006 jiffies g=111 c=110 q=990)
[   76.755178] Task dump for CPU 1:
[   76.758420] netifd          R running      0  1106      1 0x00000002
[   76.764838] [<c001fa3c>] (unwind_backtrace) from [<c001c3a4>] (show_stack+0x10/0x14)
[   76.772617] [<c001c3a4>] (show_stack) from [<c006b3b8>] (rcu_dump_cpu_stacks+0x78/0xb0)
[   76.780648] [<c006b3b8>] (rcu_dump_cpu_stacks) from [<c006e7c0>] (rcu_check_callbacks+0x28c/0x754)
[   76.789637] [<c006e7c0>] (rcu_check_callbacks) from [<c00708dc>] (update_process_times+0x38/0x64)
[   76.798543] [<c00708dc>] (update_process_times) from [<c007f738>] (tick_sched_timer+0x21c/0x260)
[   76.807358] [<c007f738>] (tick_sched_timer) from [<c0071694>] (__hrtimer_run_queues+0xf8/0x1b8)
[   76.816084] [<c0071694>] (__hrtimer_run_queues) from [<c00718ac>] (hrtimer_interrupt+0xac/0x200)
[   76.824898] [<c00718ac>] (hrtimer_interrupt) from [<c02edac0>] (armada_370_xp_timer_interrupt+0x30/0x38)
[   76.834407] [<c02edac0>] (armada_370_xp_timer_interrupt) from [<c00664f0>] (handle_percpu_devid_irq+0x6c/0x84)
[   76.844447] [<c00664f0>] (handle_percpu_devid_irq) from [<c00623c0>] (generic_handle_irq+0x24/0x34)
[   76.853521] [<c00623c0>] (generic_handle_irq) from [<c0062698>] (__handle_domain_irq+0x98/0xac)
[   76.862247] [<c0062698>] (__handle_domain_irq) from [<c0009428>] (armada_370_xp_handle_irq+0x50/0xb0)
[   76.871496] [<c0009428>] (armada_370_xp_handle_irq) from [<c000a5f4>] (__irq_svc+0x54/0x70)
[   76.879869] Exception stack(0xce1b5de8 to 0xce1b5e30)
[   76.884938] 5de0:                   00000000 cf83fca4 00000000 cf83eca4 c05c6614 cf83fca4
[   76.893141] 5e00: cf83fc80 cf83f830 00000000 00000000 00000000 00000000 cf83eca8 ce1b5e38
[   76.901341] 5e20: c0028e20 c0042198 a0000013 ffffffff
[   76.906417] [<c000a5f4>] (__irq_svc) from [<c0042198>] (raw_notifier_chain_register+0x10/0x40)
[   76.915064] [<c0042198>] (raw_notifier_chain_register) from [<c0028e20>] (register_cpu_notifier+0x28/0x3c)
[   76.924759] [<c0028e20>] (register_cpu_notifier) from [<c028d29c>] (mvneta_open+0xb8/0x170)
[   76.933147] [<c028d29c>] (mvneta_open) from [<c03164a0>] (__dev_open+0x8c/0x108)
[   76.940569] [<c03164a0>] (__dev_open) from [<c0316754>] (__dev_change_flags+0xb0/0x140)
[   76.948597] [<c0316754>] (__dev_change_flags) from [<c03167fc>] (dev_change_flags+0x18/0x48)
[   76.957072] [<c03167fc>] (dev_change_flags) from [<c032b4a8>] (dev_ifsioc+0xd0/0x320)
[   76.964928] [<c032b4a8>] (dev_ifsioc) from [<c032bf60>] (dev_ioctl+0x7f4/0x8c0)
[   76.972266] [<c032bf60>] (dev_ioctl) from [<c00da408>] (do_vfs_ioctl+0x6a4/0x6f4)
[   76.979772] [<c00da408>] (do_vfs_ioctl) from [<c00da48c>] (SyS_ioctl+0x34/0x5c)
[   76.987106] [<c00da48c>] (SyS_ioctl) from [<c0009c80>] (ret_fast_syscall+0x0/0x3c)

It seems netifd is hung (maybe in the mvneta driver)????
Has anyone else already seen this?
What is causing this?
How do I fix it?

Thanks