[Intel-gfx] [PATCH i-g-t] i915/gem_userptr_blit: Shoot down a shared mmap_gtt(userptr)

Establish a userptr and inherit it to many children with fresh mm. Into each child mm, mmap_gtt the userptr handle so that they are many different vma in the i_mapping tree pointing back to the userptr. Then proceed to munmap that and force us to revoke all the mmaps. Daniel discovered that from t

[Intel-gfx] [PATCH i-g-t] i915/gem_userptr_blit: Shoot down a shared mmap_gtt(userptr)

Establish a userptr and inherit it to many children with fresh mm. Into each child mm, mmap_gtt the userptr handle so that they are many different vma in the i_mapping tree pointing back to the userptr. Then proceed to munmap that and force us to revoke all the mmaps. Daniel discovered that from t