Re: kernel: Alignment trap

[Greg KH <greg@kroah.com>]

On Thu, Nov 21, 2019 at 05:06:45PM +1100, JH wrote:
> Hi Peter,
> 
> On 11/21/19, Peter Chen <peter.chen@nxp.com> wrote:
> > On 19-11-21 07:08:32, JH wrote:
> >> Hi Greg,
> >>
> >> On 11/21/19, Greg KH <greg@kroah.com> wrote:
> >> > On Wed, Nov 20, 2019 at 09:28:14PM +1100, JH wrote:
> >> >> Hi,
> >> >>
> >> >> I am running 4G LTE (USB protocol) and WiFi on IMX6 board, the kernel
> >> >> is 4.19.75 LTE. It is not clear where the kernel alignment trap came
> >> >> from, the only thing I could see is the alignment trap message
> >> >> generated immediate after USB GSM communication or mwifiex_sdio. Where
> >> >> that the alignment trap came from? Which parts of the program could
> >> >> contribute the kernel alignment trap, kernel iteself, or USB GSM or
> >> >> mwifiex_sdio? Appreciate clues how to fix it.
> >> >>
> >> >> Nov 20 05:08:09 solar kernel: usb 1-1: GSM modem (1-port) converter
> >> >> now attached to ttyUSB0
> >> >> Nov 20 05:08:09 solar kernel: option 1-1:1.2: GSM modem (1-port)
> >> >> converter detected
> >> >> Nov 20 05:08:09 solar kernel: usb 1-1: GSM modem (1-port) converter
> >> >> now attached to ttyUSB1
> >> >> Nov 20 05:08:10 solar kernel: mwifiex_sdio mmc0:0001:1: info: trying
> >> >> to associate to 'Solar Analytics Wifi' bssid 78:8a:20:49:4b:c5
> >> >> Nov 20 05:08:10 solar kernel: mwifiex_sdio mmc0:0001:1: info:
> >> >> associated to bssid 78:8a:20:49:4b:c5 successfully
> >> >> Nov 20 05:08:10 solar kernel: IPv6: ADDRCONF(NETDEV_CHANGE): mlan0:
> >> >> link becomes ready
> >> >> Nov 20 05:23:13 solar kernel: mwifiex_sdio mmc0:0001:1: info:
> >> >> successfully disconnected from 78:8a:20:49:4b:c5: reason code 3
> >> >> Nov 20 05:23:13 solar kernel: IPv6: ADDRCONF(NETDEV_UP): mlan0: link
> >> >> is not ready
> >> >> Nov 20 05:23:18 solar kernel: Alignment trap: not handling instruction
> >> >> e8532f00 at [<b6c802b6>]
> >> >> Nov 20 05:23:18 solar kernel: Unhandled fault: alignment exception
> >> >> (0x001) at 0x38626667
> >> >> Nov 20 05:23:18 solar kernel: pgd = 34bdb7e7
> >> >> Nov 20 05:23:18 solar kernel: [38626667] *pgd=00000000
> >> >
> >> > You should have a much longer tracedump after this, right?  Can you
> >> > provide that please?
> >>
> >> That was the last statement from the kernel log journalctl -t kernel
> >> -b at the time.
> >>
> >> > And why do you think this was a USB issue?
> >>
> >> No, I was not saying it was a USB issue, nor did I know if it is a
> >> kernel issue or mwifiex_sdio issue or something else, I don't have the
> >> knowledge to determine it, that was why I have to go this list for
> >> help, I did try to connect to Linux network mailing list linux-net or
> >> kernel mailing list lkml, but I must get wrong with the mailing list
> >> address, I could not get response or subscription frin linux-net or
> >> lkml, if you could let me know the correct kernel network mailing
> >> address and kernel mailing list address, I'll ask the help there as
> >> well.
> >>
> >
> > Do you have correct firmware has loaded for your device?
> 
> Not clear what the firmware you were talking about? I used open source
> linux-firmware-sd8887, uBlox SARA-R4 and uBlox EMMY on IMX6. Let's say
> we have been running this device for about 7 months, we used Kernel
> 5.1.0 before, I could not recall any error about the alignment trap in
> kernel. We now moved to kernel 4.19.75 LTS, that is what it occurred
> often, that worries me.

Why did you move to an older kernel?  If it all works on a newer one,
please stick with that, or use 'git bisect' to find the commit that
breaks things.

thanks,

greg k-h