linux-kernel - [PATCH] swiotlb: suppress warning when __GFP

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Message-Id: <20180104132419.24536-1-christian.koenig@amd.com>
Date:   Thu,  4 Jan 2018 14:24:19 +0100
From:   "Christian König" 
        <ckoenig.leichtzumerken@...il.com>
To:     konrad.wilk@...cle.com
Cc:     linux-kernel@...r.kernel.org, hch@...radead.org
Subject: [PATCH] swiotlb: suppress warning when __GFP_NOWARN is set v5

TTM tries to allocate coherent memory in chunks of 2MB first to improve
TLB efficiency and falls back to allocating 4K pages if that fails.

Suppress the warning when the 2MB allocations fails since there is a
valid fall back path.

v2: suppress warnings from swiotlb_tbl_map_single as well
v3: coding style fixes as suggested by Konrad
v4: make tbl_map_single static
v5: use DMA_ATTR_NO_WARN instead

Signed-off-by: Christian König <christian.koenig@....com>
Reported-by: Mike Galbraith <efault@....de>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=104082
CC: stable@...r.kernel.org
---
 lib/swiotlb.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index cea19aaf303c..0d7f46fb993a 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -586,7 +586,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
 
 not_found:
 	spin_unlock_irqrestore(&io_tlb_lock, flags);
-	if (printk_ratelimit())
+	if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
 		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size);
 	return SWIOTLB_MAP_ERROR;
 found:
@@ -713,6 +713,7 @@ void *
 swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 		       dma_addr_t *dma_handle, gfp_t flags)
 {
+	bool warn = !(flags & __GFP_NOWARN);
 	dma_addr_t dev_addr;
 	void *ret;
 	int order = get_order(size);
@@ -738,8 +739,8 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 		 * GFP_DMA memory; fall back on map_single(), which
 		 * will grab memory from the lowest available address range.
 		 */
-		phys_addr_t paddr = map_single(hwdev, 0, size,
-					       DMA_FROM_DEVICE, 0);
+		phys_addr_t paddr = map_single(hwdev, 0, size, DMA_FROM_DEVICE,
+					       warn ? 0 : DMA_ATTR_NO_WARN);
 		if (paddr == SWIOTLB_MAP_ERROR)
 			goto err_warn;
 
@@ -769,9 +770,11 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 	return ret;
 
 err_warn:
-	pr_warn("swiotlb: coherent allocation failed for device %s size=%zu\n",
-		dev_name(hwdev), size);
-	dump_stack();
+	if (warn && printk_ratelimit()) {
+		pr_warn("swiotlb: coherent allocation failed for device %s size=%zu\n",
+			dev_name(hwdev), size);
+		dump_stack();
+	}
 
 	return NULL;
 }
-- 
2.11.0