Make use of the FAULT_FLAG_ALLOW_RETRY flag to allow dropping the mmap_sem while waiting for bo idle.
FAULT_FLAG_ALLOW_RETRY appears to be primarily designed for disk waits but should work just as fine for GPU waits..
Signed-off-by: Thomas Hellstrom thellstrom@vmware.com --- drivers/gpu/drm/ttm/ttm_bo_vm.c | 62 +++++++++++++++++++++++++++++++-------- 1 file changed, 50 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index 1006c15..c03514b 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -41,6 +41,51 @@
#define TTM_BO_VM_NUM_PREFAULT 16
+static int ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo, + struct vm_area_struct *vma, + struct vm_fault *vmf) +{ + struct ttm_bo_device *bdev = bo->bdev; + int ret = 0; + + spin_lock(&bdev->fence_lock); + if (likely(!test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags))) + goto out_unlock; + + /* + * Quick non-stalling check for idle. + */ + ret = ttm_bo_wait(bo, false, false, true); + if (likely(ret == 0)) + goto out_unlock; + + /* + * If possible, avoid waiting for GPU with mmap_sem + * held. + */ + if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) { + ret = VM_FAULT_RETRY; + if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) + goto out_unlock; + + up_read(&vma->vm_mm->mmap_sem); + (void) ttm_bo_wait(bo, false, true, false); + goto out_unlock; + } + + /* + * Ordinary wait. + */ + ret = ttm_bo_wait(bo, false, true, false); + if (unlikely(ret != 0)) + ret = (ret != -ERESTARTSYS) ? VM_FAULT_SIGBUS : + VM_FAULT_NOPAGE; + +out_unlock: + spin_unlock(&bdev->fence_lock); + return ret; +} + static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf) { struct ttm_buffer_object *bo = (struct ttm_buffer_object *) @@ -91,18 +136,11 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf) * Wait for buffer data in transit, due to a pipelined * move. */ - - spin_lock(&bdev->fence_lock); - if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) { - ret = ttm_bo_wait(bo, false, true, false); - spin_unlock(&bdev->fence_lock); - if (unlikely(ret != 0)) { - retval = (ret != -ERESTARTSYS) ? - VM_FAULT_SIGBUS : VM_FAULT_NOPAGE; - goto out_unlock; - } - } else - spin_unlock(&bdev->fence_lock); + ret = ttm_bo_vm_fault_idle(bo, vma, vmf); + if (unlikely(ret != 0)) { + retval = ret; + goto out_unlock; + }
ret = ttm_mem_io_lock(man, true); if (unlikely(ret != 0)) {