ttm_device_swapout
ret = ttm_device_swapout(bdev, &ctx, GFP_KERNEL);
ret = ttm_device_swapout(bdev, ctx, gfp_flags);
EXPORT_SYMBOL(ttm_device_swapout);
while (ttm_device_swapout(&dev_priv->bdev, &ctx, GFP_KERNEL) > 0);
int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,