[LEDE-DEV] kernel NULL pointer issue in latest master branch with rt2800usb rt2800lib rt2x00usb rt2x00lib

[TheWerthFam]

(Duplicate sent to openwrt-devel list - I'm on both lists)
Running latest development branch on my bpi-r1 my system for the past 
few weeks and find that the system is crashing about every 36 hours.  It 
seems that it crashed when its under a little CPU load or multiple 
processes are actually doing work.  I run e2guargian and squid on my 
router. When this crash happens it seems that cpu load is still low 10 - 
20% range.
I just switched to this branch vs the 17.01x series about 2 weeks ago in 
an effort to help test the new version before it is released.  At that 
time the B53 switch drivers were not being loaded, seems some difference 
in the 4.9 and 4.14 versions of the kernel.  This patch was created and 
fixed the switch issue.
https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=b7b14fd64e09b523b2da6a9db6d7ff300964b955

I use a ralink RT chipset 5592 because the onboard 8291cu chip & drivers 
are junk. The ralink card has worked great for years on the 17.x and 
prior kernel versions.

crash dump

[45729.124237] Unable to handle kernel NULL pointer deref8

[45729.132661] pgd = edc4ad00

[45729.135502] [00000028] *pgd=6e733003, *pmd=7fc26003

[45729.140895] Internal error: Oops: 207 [#1] PREEMPT SMP ARM

[45729.146387] Modules linked in: rt2800usb rt2800lib rt2x00usb 
rt2x00lib pppoet

[45729.217382]  ip_set_bitmap_ipmac ip_set_bitmap_ip ip_set nfnetlink 
ip6t_REJEm

[45729.235828] CPU: 0 PID: 4028 Comm: e2guardian Not tainted 4.14.25 #0

[45729.242172] Hardware name: Allwinner sun7i (A20) Family

[45729.247391] task: edf71500 task.stack: edf7c000

[45729.251928] PC is at tcp_push+0x44/0xfc

[45729.255761] LR is at 0xed34eb34

[45729.258899] pc : [<c06285d4>]    lr : [<ed34eb34>] psr: 40000013

[45729.265156] sp : edf7de00  ip : ed416780 fp : ed34eb34

[45729.270373] r10: ed416780  r9 : 0000a9b0 r8 : 00000000

[45729.275591] r7 : 0000da53  r6 : ed34ea40 r5 : 00000000 r4 : ffffffe0

[45729.282108] r3 : 00000001  r2 : 000005a8 r1 : 00000000 r0 : ed34ea40

[45729.288628] Flags: nZcv  IRQs on FIQs on Mode SVC_32  ISA ARM Segment 
user

[45729.295754] Control: 30c5387d  Table: 6dc4ad00 DAC: fffffffd

[45729.301493] Process e2guardian (pid: 4028, stack limit = 0xedf7c210)

[45729.307838] Stack: (0xedf7de00 to 0xedf7e000)

[45729.312195] de00: ffffffe0 0000da53 ed34ea40 0000da53 edf7dedc 
0000da53 ed414



Few relevant portions of the kernel boot log
Linux 4.14.27 #0 SMP PREEMPT Wed Mar 21 22:24:09 2018 armv7l GNU/x

[    2.307730] usb 1-1: New USB device found, idVendor=148f, idProduct=5572
[    2.314578] usb 1-1: New USB device strings: Mfr=1, Product=2, 
SerialNumber=3
[    2.321805] usb 1-1: Product: 802.11 n WLAN
[    2.326064] usb 1-1: Manufacturer: Ralink
[    2.330131] usb 1-1: SerialNumber: 1.0
   9.630858] usb 1-1: reset high-speed USB device number 2 using 
ehci-platform
[    9.840191] ieee80211 phy0: rt2x00_set_rt: Info - RT chipset 5592, 
rev 0222 detected
[    9.876184] ieee80211 phy0: rt2x00_set_rf: Info - RF chipset 000f 
detected
[    9.884937] ieee80211 phy0: Selected rate control algorithm 
'minstrel_ht'
[    9.888448] usbcore: registered new interface driver rt2800usb
[    9.894671] kmodloader: done loading kernel modules from 
/etc/modules.d/*
    14.337032] ieee80211 phy0: rt2x00lib_request_firmware: Info - 
Loading firmware file 'rt2870.bin'
[   14.350912] ieee80211 phy0: rt2x00lib_request_firmware: Info - 
Firmware detected - version: 0.36


Any advice on fixing this issue?
Thanks
     Derek