Deadlock under load with Linux 5.9 and other recent kernels

[Christian Hewitt]

> 
> On 26 Sep 2020, at 2:51 pm, Jens Axboe <axboe at kernel.dk> wrote:
> 
> On 9/26/20 1:55 AM, Christian Hewitt wrote:
>> I am using an ARM SBC device with Amlogic S922X chip (Beelink
>> GS-King-X, an Android STB) to boot the Kodi mediacentre distro
>> LibreELEC (which I work on) although the issue is also reproducible
>> with Manjaro and Armbian on the same hardware, and with the GT-King
>> and GT-King Pro devices from the same vendor - all three devices are
>> using a common dtsi:
>> 
>> https://github.com/chewitt/linux/blob/amlogic-5.9-integ/arch/arm64/boot/dts/amlogic/meson-g12b-gsking-x.dts
>> https://github.com/chewitt/linux/blob/amlogic-5.9-integ/arch/arm64/boot/dts/amlogic/meson-g12b-gtking-pro.dts
>> https://github.com/chewitt/linux/blob/amlogic-5.9-integ/arch/arm64/boot/dts/amlogic/meson-g12b-gtking.dts
>> https://github.com/chewitt/linux/blob/amlogic-5.9-integ/arch/arm64/boot/dts/amlogic/meson-g12b-w400.dtsi
>> 
>> I have schematics for the devices, but can only share those privately
>> on request.
>> 
>> For testing I am booting LibreELEC from SD card. The box has a 4TB
>> SATA drive internally connected with a USB > SATA bridge, see dmesg:
>> http://ix.io/2yLh and I connect a USB stick with a 4GB ISO file that I
>> copy to the internal SATA drive. Within 10-20 seconds of starting the
>> copy the box deadlocks needing a hard power cycle to recover. The
>> timing of the deadlock is variable but the device _always_ deadlocks.
>> Although I am using a simple copy use-case, there are similar reports
>> in Armbian forums performing tasks like installs/updates that involve
>> I/O loads.
>> 
>> Following advice in the #linux-amlogic IRC channel I added
>> CONFIG_SOFTLOCKUP_DETECTOR and CONFIG_DETECT_HUNG_TASK and was able to
>> get output on the HDMI screen (it is not possible to connect to UART
>> pins without destroying the box case). If you advance the following
>> video frame by frame in VLC you can see the output:
>> 
>> https://www.dropbox.com/s/klvcizim8cs5lze/lockup_clip.mov?dl=0
> 
> Try with this patch:
> 
> https://lore.kernel.org/linux-block/20200925191902.543953-1-shakeelb@google.com/

It still locks up approx. 25 seconds into the copy operation. Here’s the output in video again (a little blurry):

https://www.dropbox.com/s/3j2czaq509arg6g/lockup_clip2.mov?dl=0

Christian