Comment # 2 on bug 81991 from Michel Dänzer

(In reply to comment #1)
> This is a kernel out of memory error not a driver bug.  The driver is not
> able to allocate the memory it needs.

That may be technically true, but order 4 means 16 physically contiguous pages
IIUC, which may be difficult for the kernel to provide. We can avoid this by
making radeon_vm_get_bos() allocate each list node separately instead of a
single large array for all of them.