tree 9d24fd8ae33382963d8f2afbcb9f7d31320d58db
parent 6c55d6e90e68a4789cbd72a0287026d4dfb4a9f9
author Philip Yang <Philip.Yang@amd.com> 1551728463 -0500
committer Alex Deucher <alexander.deucher@amd.com> 1558718462 -0500

drm/amdgpu: support userptr cross VMAs case with HMM

userptr may cross two VMAs if the forked child process (not call exec
after fork) malloc buffer, then free it, and then malloc larger size
buf, kerenl will create new VMA adjacent to old VMA which was cloned
from parent process, some pages of userptr are in the first VMA, the
rest pages are in the second VMA.

HMM expects range only have one VMA, loop over all VMAs in the address
range, create multiple ranges to handle this case. See
is_mergeable_anon_vma in mm/mmap.c for details.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>