mutter segfault after lockscreen
I've just updated the latest master mutter + gnome-shell and I can now reproduce this at will.
This is one a skylake iGPU with 2 1920x1080 screens and some X11 apps running.
If I do "Super + L", wait a few seconds for the monitors to go black and then start typing my unlock password, the sliding away of the lockscreen (to show the passwd entry field) starts and roughly about halfway through gnome-shell crashes.
Here is the backtrace from the journal:
#0 0x00007f16110cdc0a notify_view_crtc_presented (libmutter-5.so.0)
#1 0x00007f16110cddb8 page_flip_feedback_flipped (libmutter-5.so.0)
#2 0x00007f16110d5024 flush_callbacks (libmutter-5.so.0)
#3 0x00007f16110d54c3 meta_kms_flush_callbacks (libmutter-5.so.0)
#4 0x00007f16110d1b1a meta_kms_device_dispatch_sync (libmutter-5.so.0)
#5 0x00007f16110c85e1 meta_gpu_kms_wait_for_flip (libmutter-5.so.0)
#6 0x00007f16110ccbec wait_for_pending_flips (libmutter-5.so.0)
#7 0x00007f1610adb05e cogl_onscreen_swap_buffers_with_damage (libmutter-cog
#8 0x00007f161129be18 swap_framebuffer (libmutter-clutter-5.so.0)
#9 0x00007f161129c5ab clutter_stage_cogl_redraw (libmutter-clutter-5.so.0)
#10 0x00007f161125b7af clutter_stage_do_redraw (libmutter-clutter-5.so.0)
#11 0x00007f1611245099 master_clock_update_stages (libmutter-clutter-5.so.0)
#12 0x00007f1611bec470 g_main_context_dispatch (libglib-2.0.so.0)
#13 0x00007f1611bec800 g_main_context_iterate.isra.0 (libglib-2.0.so.0)
#14 0x00007f1611becaf3 g_main_loop_run (libglib-2.0.so.0)
#15 0x00007f1611053d90 meta_run (libmutter-5.so.0)
#16 0x000055cb609e4cad main (gnome-shell)
#17 0x00007f1610dfb193 __libc_start_main (libc.so.6)
#18 0x000055cb609e4e8e _start (gnome-shell)
When the crash happens I get a bunch of lines with this warning in my journal before the crash:
gnome-shell[24363]: (../src/backends/native/meta-renderer-native.c:2211):meta_onscreen_native_swap_buffers_with_damage: runtime check failed: (onscreen_native->gbm.next_fb == NULL)
I can fix this by going to a slightly older checkout from master, so I'm bisecting this now.