Am 15.09.21 um 20:59 schrieb Matthew Auld:
In commit:
commit 58aa6622d32af7d2c08d45085f44c54554a16ed7 Author: Thomas Hellstrom thellstrom@vmware.com Date: Fri Jan 3 11:47:23 2014 +0100
drm/ttm: Correctly set page mapping and -index memberswe started setting the page->mapping and page->index to point to the virtual address space, if the pages were faulted with TTM. Apparently this was needed for core-mm to able to reverse lookup the virtual address given the struct page, and potentially unmap it from the page tables. However as pointed out by Thomas, since we are now using PFN_MAP, instead of say PFN_MIXED, this should no longer be the case.
There was also apparently some usecase in vmwgfx which needed this for dirty tracking, but that also doesn't appear to be the case anymore, as pointed out by Thomas.
We still need keep the page->mapping for now, since that is still needed for different reasons, but we try to address that in the next patch.
Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Thomas Hellström thomas.hellstrom@linux.intel.com Cc: Christian König christian.koenig@amd.com
Reviewed-by: Christian König christian.koenig@amd.com
Fingers crossed that this really works as documented.
drivers/gpu/drm/ttm/ttm_bo_vm.c | 2 -- drivers/gpu/drm/ttm/ttm_tt.c | 4 +--- 2 files changed, 1 insertion(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index f56be5bc0861..906ec8a1bf5a 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -346,8 +346,6 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf, } else if (unlikely(!page)) { break; }
page->index = drm_vma_node_start(&bo->base.vma_node) +page_offset; pfn = page_to_pfn(page);diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c index dae52433beeb..1cc04c224988 100644 --- a/drivers/gpu/drm/ttm/ttm_tt.c +++ b/drivers/gpu/drm/ttm/ttm_tt.c @@ -367,10 +367,8 @@ static void ttm_tt_clear_mapping(struct ttm_tt *ttm) if (ttm->page_flags & TTM_PAGE_FLAG_SG) return;
- for (i = 0; i < ttm->num_pages; ++i) {
- for (i = 0; i < ttm->num_pages; ++i) (*page)->mapping = NULL;
(*page++)->index = 0;} }
void ttm_tt_unpopulate(struct ttm_device *bdev, struct ttm_tt *ttm)