Hello,
Same issue for me, same symptoms, I was using lightdm with autologin and a kodi session, but any other session triggers the same bug.
GPU: AMD A10-7800 Radeon R7 APU
Here is my stack from Xorg.0.log
[ 38.969] (EE) 0: /usr/lib/xorg/Xorg (OsLookupColor+0x14d)
[0x561b023f0f9d]
[ 38.969] (EE) 1: /lib/x86_64-linux-gnu/libc.so.6
(__sigaction+0x40) [0x7f0190abd510]
[ 38.988] (EE) 2: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0x275d) [0x7f018e1c586d]
[ 38.988] (EE) 3: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0x4841) [0x7f018e1c7951]
[ 38.992] (EE) 4: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(_ZNSt6vectorIjSaIjEE17_M_default_appendEm+0xa77e6)
[0x7f018e6c9476]
[ 38.992] (EE) 5: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(_ZNSt6vectorIjSaIjEE17_M_default_appendEm+0xa7989)
[0x7f018e6c9619]
[ 38.993] (EE) 6: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0x3aba) [0x7f018e1c6bca]
[ 38.995] (EE) 7: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0x137795) [0x7f018e2fa8a5]
[ 38.996] (EE) 8: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0x137b68) [0x7f018e2fac78]
[ 38.996] (EE) 9: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0x138387) [0x7f018e2fb497]
[ 38.997] (EE) 10:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0xb6dba) [0x7f018e279eca]
[ 38.997] (EE) 11:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0xb91b8) [0x7f018e27c2c8]
[ 38.998] (EE) 12:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0xbe181) [0x7f018e281291]
[ 38.998] (EE) 13:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0xf0208) [0x7f018e2b3318]
[ 38.998] (EE) 14:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(radeon_drm_winsys_create+0xf4aa9) [0x7f018e2b7bb9]
[ 39.003] (EE) 15:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(_ZNSt6vectorIjSaIjEE17_M_default_appendEm+0x1cc3e9)
[0x7f018e7ee079]
[ 39.003] (EE) 16:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(_ZNSt6vectorIjSaIjEE17_M_default_appendEm+0x1d7ee3)
[0x7f018e7f9b73]
[ 39.009] (EE) 17:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(__driDriverGetExtensions_d3d12+0x5c81c7) [0x7f018e079557]
[ 39.010] (EE) 18:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(__driDriverGetExtensions_d3d12+0x5c1016) [0x7f018e0723a6]
[ 39.010] (EE) 19:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(__driDriverGetExtensions_d3d12+0x5c19b8) [0x7f018e072d48]
[ 39.011] (EE) 20:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(__driDriverGetExtensions_d3d12+0x5c9b75) [0x7f018e07af05]
[ 39.015] (EE) 21:
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so
(__driDriverGetExtensions_d3d12+0xb82c4) [0x7f018db69654]
[ 39.015] (EE) 22: /usr/lib/xorg/modules/libglamoregl.so
(glamor_destroy_pixmap+0x150) [0x7f0185d7acf0]
[ 39.016] (EE) unw_get_proc_name failed: no unwind info found
[-10]
[ 39.016] (EE) 23: /usr/lib/xorg/modules/drivers/radeon_drv.so
(?+0x0) [0x7f018fe7fcdf]
[ 39.016] (EE) 24: /usr/lib/xorg/Xorg (BlockHandler+0xad)
[0x561b0227fe0d]
[ 39.016] (EE) 25: /usr/lib/xorg/Xorg (WaitForSomething+0x153)
[0x561b023ea703]
[ 39.016] (EE) 26: /usr/lib/xorg/Xorg (SendErrorToClient+0x117)
[0x561b0227b097]
[ 39.016] (EE) 27: /usr/lib/xorg/Xorg (InitFonts+0x3bc)
[0x561b0227f3bc]
[ 39.017] (EE) 28: /lib/x86_64-linux-gnu/libc.so.6
(__libc_init_first+0x8a) [0x7f0190aa86ca]
[ 39.017] (EE) 29: /lib/x86_64-linux-gnu/libc.so.6
(__libc_start_main+0x85) [0x7f0190aa8785]
[ 39.017] (EE) 30: /usr/lib/xorg/Xorg (_start+0x21)
[0x561b02268281]
[ 39.017] (EE)
[ 39.017] (EE) Segmentation fault at address 0x40
Best regards,
-- Julien Leproust