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Commit 4133d4c6 authored by Vinayak Menon's avatar Vinayak Menon Committed by Gerrit - the friendly Code Review server
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iommu: do not attempt reclaim on higher order allocs 



Attempting reclaim for non-zero order allocations can result in
the context blocked in reclaim for unpredictable amounts of time.
There are cases reported where dma_alloc_attrs gets blocked for
20+ seconds for an allocation of 200MB. Since higher order
allocation is not a necessity in the presence of iommu, avoid
reclaim.

Change-Id: I93f57e2ea5f7c57ec84a92911e2aae36112d95e1
Signed-off-by: default avatarVinayak Menon <vinmenon@codeaurora.org>
parent 45cef796

arch/arm64/mm/dma-mapping.c

+8 −3
Original line number Diff line number Diff line
@@ -1288,9 +1288,14 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, 
	while (count) {

		int j, order = __fls(count);



		pages[i] = alloc_pages(gfp, order);

		while (!pages[i] && order)

			pages[i] = alloc_pages(gfp, --order);

		pages[i] = alloc_pages(order ? (gfp | __GFP_NORETRY) &

					~__GFP_RECLAIM : gfp, order);

		while (!pages[i] && order) {

			order--;

			pages[i] = alloc_pages(order ? (gfp | __GFP_NORETRY) &

					~__GFP_RECLAIM : gfp, order);

		}



		if (!pages[i])

			goto error;

drivers/iommu/dma-iommu.c

+3 −2
Original line number Diff line number Diff line
@@ -369,8 +369,9 @@ static struct page **__iommu_dma_alloc_pages(unsigned int count, 
			unsigned int order = __fls(order_mask);



			order_size = 1U << order;

			page = alloc_pages((order_mask - order_size) ?

					   gfp | __GFP_NORETRY : gfp, order);

			page = alloc_pages(order ?

					   (gfp | __GFP_NORETRY) &

						~__GFP_RECLAIM : gfp, order);

			if (!page)

				continue;

			if (!order)