[Bug 1948894] Re: Xwayland crash in gdm as screen off and touchscreen detach.

[Yuan-Chen Cheng]

debdiff for impish

** Patch added: "mutter_40.5-1ubuntu3~21.04.1.debdiff"
   https://bugs.launchpad.net/oem-priority/+bug/1948894/+attachment/5537399/+files/mutter_40.5-1ubuntu3~21.04.1.debdiff

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Title:
  Xwayland crash in gdm as screen off and touchscreen detach.

Status in Mutter:
  Unknown
Status in OEM Priority Project:
  In Progress
Status in X.Org X server:
  Unknown
Status in mutter package in Ubuntu:
  Fix Committed
Status in mutter package in Fedora:
  Unknown

Bug description:
  This is a reproducible issue. Step to reproduce
  1. cold boot into gdm login screen.
  2. wait for 5 mins, and the screen will be turned off. (also observed that the touchscreen USB device drop of a USB bus on the target machine)

  Note: this bug seems to be timing sensitive. I got an OEM project
  machine that can reproduce this issue (reproducible on several
  machines with the same HW design). The machine is using ADL CPU, which
  needs a patched 5.14 kernel. So I can't reproduce this on impish. With
  the backported mutter, I verified an upstream patch seems to fix this
  issue.

  Expected result:
  The screen just turns black.

  Actual result:
  Saw Vendor boot logo on the monitor (previous draw by plymouth during booting)

  Analysis as it happens:
  1. Saw "LGDisplay Incell Touch" drop off the USB bus.
     Kernel message like: "usb 1-9: USB disconnect, device number 6"
     as the screen turned black.
  2. There is no switch on virtual tty.
  3. journal log from Xwayland "wl_display at 1: error 0: invalid object 24"
  4. Xwayland and gnome-shell process both die as this happens.
  5. Try to add sleep(30) to OsVendorFatalError(), then both Xwayland and
     gnome-shell stop there for 30 more seconds.
  6. backtrace as Xwayland crashed:

  ```
  #0 0x00007f447b8e818b in raise () from /lib/x86_64-linux-gnu/libc.so.6
  #1 0x00007f447b8c7859 in abort () from /lib/x86_64-linux-gnu/libc.so.6
  #2 0x0000564374403f30 in OsAbort () at ../../../../os/utils.c:1351
  #3 0x0000564374409369 in AbortServer () at ../../../../os/log.c:872
  #4 0x000056437440a1ca in FatalError (f=f at entry=0x564374416266 "%s") at ../../../../os/log.c:1010
  #5 0x000056437429c8b0 in xwl_log_handler (format=<optimized out>, args=<optimized out>) at ../../../../../hw/xwayland/xwayland.c:1312
  #6 0x00007f447c3d027e in wl_log (fmt=fmt at entry=0x7f447c3d121a "%s@%u: error %d: %s\n") at ../src/wayland-util.c:404
  #7 0x00007f447c3cb78b in display_handle_error (data=<optimized out>, display=0x56437639f000, object=0x56437639f000, code=0, message=<optimized out>)
      at ../src/wayland-client.c:911
  #8 0x00007f447b7c0ff5 in ?? () from /lib/x86_64-linux-gnu/libffi.so.7
  #9 0x00007f447b7c040a in ?? () from /lib/x86_64-linux-gnu/libffi.so.7
  #10 0x00007f447c3cf3a8 in wl_closure_invoke (closure=closure at entry=0x564376e57350, flags=flags at entry=1, target=<optimized out>,
      target at entry=0x56437639f000, opcode=opcode at entry=0, data=<optimized out>) at ../src/connection.c:1018
  #11 0x00007f447c3cbc48 in dispatch_event (display=display at entry=0x56437639f000, queue=<optimized out>) at ../src/wayland-client.c:1445
  #12 0x00007f447c3cd1ef in dispatch_queue (queue=0x56437639f0d0, display=0x56437639f000) at ../src/wayland-client.c:1584
  #13 wl_display_dispatch_queue_pending (display=0x56437639f000, queue=0x56437639f0d0) at ../src/wayland-client.c:1833
  #14 0x00007f447c3cd280 in wl_display_dispatch_pending (display=<optimized out>) at ../src/wayland-client.c:1896
  #15 0x000056437429c9bb in xwl_read_events (xwl_screen=0x564376399dd0) at ../../../../../hw/xwayland/xwayland.c:957
  #16 0x0000564374401c61 in ospoll_wait (ospoll=0x56437638f4a0, timeout=<optimized out>) at ../../../../os/ospoll.c:657
  #17 0x00005643743faa23 in WaitForSomething (are_ready=0) at ../../../../os/WaitFor.c:208
  #18 0x00005643743ca4a7 in Dispatch () at ../../../../include/list.h:220
  #19 0x00005643743ce794 in dix_main (argc=16, argv=0x7ffc44d49298, envp=<optimized out>) at ../../../../dix/main.c:276
  #20 0x00007f447b8c90b3 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
  #21 0x000056437429c60e in _start ()```

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