[patch] swiotlb: fix ignored DMA_ATTR_NO_WARN request

[Mike Galbraith]

In the trace below, swiotlb_alloc() is called with __GFP_NOWARN, it ors
attrs with DMA_ATTR_NO_WARN and passes it to swiotlb_alloc_buffer(),
which does NOT pass it on to swiotlb_tbl_map_single(), leading to an
ever repeating warning that the caller of swiotlb_alloc() explicitly
asked to be squelched.  Pass the caller's request for silence onward.

 Xorg-3170  [006] ....   963.866098: swiotlb_alloc+0x1d/0x1a0: gfp & __GFP_NOWARN
 Xorg-3170  [006] ....   963.866101: <stack trace>
 => ttm_dma_populate+0x250/0x310 [ttm]
 => ttm_tt_populate+0x28/0x70 [ttm]
 => ttm_tt_bind+0x26/0x60 [ttm]
 => ttm_bo_handle_move_mem+0x51a/0x580 [ttm]
 => ttm_bo_validate+0xfa/0x110 [ttm]
 => ttm_bo_init_reserved+0x296/0x450 [ttm]
 => ttm_bo_init+0x73/0xd0 [ttm]
 => nouveau_bo_new+0x3eb/0x5c0 [nouveau]
 => nouveau_gem_new+0x66/0x110 [nouveau]
 => nouveau_gem_ioctl_new+0x48/0xc0 [nouveau]
 => drm_ioctl_kernel+0x66/0xb0 [drm]
 => drm_ioctl+0x28d/0x340 [drm]
 => nouveau_drm_ioctl+0x50/0xb0 [nouveau]
 => do_vfs_ioctl+0x92/0x5e0
 => ksys_ioctl+0x3a/0x70
 => __x64_sys_ioctl+0x16/0x20
 => do_syscall_64+0x5b/0x180
 => entry_SYSCALL_64_after_hwframe+0x44/0xa9
 Xorg-3170  [006] ....   963.866917: swiotlb_tbl_map_single+0x29b/0x2d0: swiotlb buffer is full (sz: 2097152 bytes)

Signed-off-by: Mike Galbraith <efault@xxxxxx>
---
 lib/swiotlb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -714,7 +714,7 @@ swiotlb_alloc_buffer(struct device *dev,
 
 	phys_addr = swiotlb_tbl_map_single(dev,
 			__phys_to_dma(dev, io_tlb_start),
-			0, size, DMA_FROM_DEVICE, 0);
+			0, size, DMA_FROM_DEVICE, attrs);
 	if (phys_addr == SWIOTLB_MAP_ERROR)
 		goto out_warn;