Comment 37 for bug 1751268

Per logs you have selftests enabled:

[ 0.377402] drm_mm: Testing DRM range manger (struct drm_mm), with random_seed=0x9292e37 max_iterations=8192 max_prime=128
[ 0.377756] drm_mm: igt_sanitycheck - ok!
[ 0.377962] igt_debug 0x0000000000000000-0x0000000000000200: 512: free
[ 0.377963] igt_debug 0x0000000000000200-0x0000000000000600: 1024: used
[ 0.377963] igt_debug 0x0000000000000600-0x0000000000000a00: 1024: free
[ 0.377964] igt_debug 0x0000000000000a00-0x0000000000000e00: 1024: used
[ 0.377965] igt_debug 0x0000000000000e00-0x0000000000001000: 512: free
[ 0.377966] igt_debug total: 4096, used 2048 free 2048

Use

CONFIG_DRM_DEBUG_SELFTEST=n
CONFIG_DRM_I915_DEBUG=n