Crash when using H264 and MJPEG M2M encoders on V4L2_MEMORY_DMABUF buffers

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
30/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
c, linux
Domain
embedded-iot, operating-systems

Research direction

Reproduce the crash with the TC358743 setup, V4L2_MEMORY_DMABUF buffers, and the ustreamer command shown in the issue. Start by examining the video_encode V4L2 M2M path and the resulting dmesg messages. Done means H264 and MJPEG can run simultaneously for many hours without a kernel crash.

Written by the indexing model from the issue text.

Description

Describe the bug
When encoding H264 and MJPEG simultaneously using V4L2 M2M encoders (video_encode component), when the image source buffer is of type V4L2_MEMORY_DMABUF, a kernel crash occurs after a few minutes.

To reproduce
0. TC358743 video capture and any 1080p signal source are used for reproducing.

  1. Add cma=128M to /boot/cmdline.txt.
  2. Add this to /boot/config.txt (some used to debug): 
    gpu_mem=128
enable_uart=1
dtoverlay=tc358743
dtoverlay=disable-bt
start_x1=1
  3. Compile ustreamer: 
    sudo apt-get install git libevent-dev libjpeg9-dev libbsd-dev
git clone --depth=1 --branch=m2m https://github.com/pikvm/ustreamer
cd ustreamer
make -j5
  4. Download and apply EDID: 
    wget https://raw.githubusercontent.com/pikvm/kvmd/master/configs/kvmd/tc358743-edid.hex
v4l2-ctl --device=/dev/video0 --set-edid=file=tc358743-edid.hex --fix-edid-checksums
  5. Run ustreamer. Wait 5-10 minutes and you will see the crash in dmesg. After that, you will be able to press Ctrl+C on ustreamer and see a few more messages related to this: 
    ./ustreamer --device=/dev/video0 --persistent --dv-timings --format=uyvy --encoder=m2m-video --workers=1 --h264-sink=test --host=::

Expected behaviour
No crash and stable operation for many hours.

Actual behaviour
Crash, pain and despair.

System
raspinfo.txt

Logs
See raspinfo ^^^

Dominant language
C
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