From: Thomas Hellstrom thellstrom@vmware.com
commit 941f2f72dbbe0cf8c2d6e0b180a8021a0ec477fa upstream.
Commit 4daa4fba3a38 ("gpu: drm: ttm: Adding new return type vm_fault_t") broke TTM prefaulting. Since vmf_insert_mixed() typically always returns VM_FAULT_NOPAGE, prefaulting stops after the second PTE.
Restore (almost) the original behaviour. Unfortunately we can no longer with the new vm_fault_t return type determine whether a prefaulting PTE insertion hit an already populated PTE, and terminate the insertion loop. Instead we continue with the pre-determined number of prefaults.
Fixes: 4daa4fba3a38 ("gpu: drm: ttm: Adding new return type vm_fault_t") Cc: Souptick Joarder jrdr.linux@gmail.com Cc: Christian König christian.koenig@amd.com Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Reviewed-by: Christian König christian.koenig@amd.com Cc: stable@vger.kernel.org # v4.19+ Signed-off-by: Christian König christian.koenig@amd.com Link: https://patchwork.freedesktop.org/patch/330387/ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/ttm/ttm_bo_vm.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-)
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -273,15 +273,13 @@ static vm_fault_t ttm_bo_vm_fault(struct else ret = vmf_insert_pfn(&cvma, address, pfn);
- /* - * Somebody beat us to this PTE or prefaulting to - * an already populated PTE, or prefaulting error. - */ - - if (unlikely((ret == VM_FAULT_NOPAGE && i > 0))) - break; - else if (unlikely(ret & VM_FAULT_ERROR)) - goto out_io_unlock; + /* Never error on prefaulted PTEs */ + if (unlikely((ret & VM_FAULT_ERROR))) { + if (i == 0) + goto out_io_unlock; + else + break; + }
address += PAGE_SIZE; if (unlikely(++page_offset >= page_last))