[regression, bisected] polaris10: *ERROR* Couldn't update BO_VA (-12) on MIPS64, PPC64, and maybe other non-4K-page systems

Brief summary of the problem:

When I opened something using OpenGL (for example, gtk3-demo's "OpenGL Area") under Xorg, Xorg hangs. The system (except the graphic) is still running and I could use ssh to get a dmesg.

Bisection suggests that "drm/amdgpu: nuke amdgpu_vm_bo_split_mapping v2" (a39f2a8d70666ef728497651a16bca4d23ec8816) is the first bad commit. Reverting it can fix this issue.

Hardware description:

• CPU: Loongson 3A4000 (MIPS64 EL)
• GPU: RX 550 (640 SP), with 4GB VRAM
• System Memory: 8 GB
• Display(s): AOC 273HU
• Type of Diplay Connection: HDMI

System infomration:

• Distro name and Version: Linux From Scratch
• Kernel version: 5.12.0-rc4+
• Custom kernel: Kernel from Linus' tree, commit e138138003eb3b3d06cc91cf2e8c5dec77e2a31e
• AMD package version: No package

How to reproduce the issue:

• startx in Linux console,
• gtk3-demo in xterm,
• Double click on OpenGL Area to start the demo,
• Now Xorg hangs.

Attached files:

• Dmesg log: dmesg.log
• Xorg log Xorg.0.log