hmm_range_fault() returns an array of page frame numbers and flags for how the pages are mapped in the requested process' page tables. The PFN can be used to get the struct page with hmm_pfn_to_page() and the page size order can be determined with compound_order(page) but if the page is larger than order 0 (PAGE_SIZE), there is no indication that the page is mapped using a larger page size. To be fully general, hmm_range_fault() would need to return the mapping size to handle cases like a 1GB compound page being mapped with 2MB PMD entries. However, the most common case is the mapping size the same as the underlying compound page size. This series adds a new output flag to indicate this so that callers know it is safe to use a large device page table mapping if one is available. Nouveau and the HMM tests are updated to use the new flag.
Note that this series depends on a patch queued in Ben Skeggs' nouveau tree ("nouveau/hmm: map pages after migration") and the patches queued in Jason's HMM tree. There is also a patch outstanding ("nouveau/hmm: fix nouveau_dmem_chunk allocations") that is independent of the above and could be applied before or after.
Ralph Campbell (6): nouveau/hmm: map pages after migration nouveau: make nvkm_vmm_ctor() and nvkm_mmu_ptp_get() static nouveau/hmm: fault one page at a time mm/hmm: add output flag for compound page mapping nouveau/hmm: support mapping large sysmem pages hmm: add tests for HMM_PFN_COMPOUND flag
drivers/gpu/drm/nouveau/nouveau_dmem.c | 46 ++- drivers/gpu/drm/nouveau/nouveau_dmem.h | 2 + drivers/gpu/drm/nouveau/nouveau_svm.c | 288 +++++++++--------- drivers/gpu/drm/nouveau/nouveau_svm.h | 5 + .../gpu/drm/nouveau/nvkm/subdev/mmu/base.c | 6 +- .../gpu/drm/nouveau/nvkm/subdev/mmu/priv.h | 2 + drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 12 +- drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h | 3 - .../drm/nouveau/nvkm/subdev/mmu/vmmgp100.c | 29 +- include/linux/hmm.h | 4 +- lib/test_hmm.c | 2 + lib/test_hmm_uapi.h | 2 + mm/hmm.c | 10 +- tools/testing/selftests/vm/hmm-tests.c | 76 +++++ 14 files changed, 311 insertions(+), 176 deletions(-)