Commit 61883d3c authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Andrew Morton
Browse files

iommu: fix MAX_ORDER usage in __iommu_dma_alloc_pages() 

MAX_ORDER is not inclusive: the maximum allocation order buddy allocator
can deliver is MAX_ORDER-1.

Fix MAX_ORDER usage in __iommu_dma_alloc_pages().

Also use GENMASK() instead of hard to read "(2U << order) - 1" magic.

Link: https://lkml.kernel.org/r/20230315113133.11326-10-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarRobin Murphy <robin.murphy@arm.com>
Reviewed-by: default avatarJacob Pan <jacob.jun.pan@linux.intel.com>
Acked-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7a16d7c7

drivers/iommu/dma-iommu.c

+2 −2
Original line number Diff line number Diff line
@@ -736,7 +736,7 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev, 
	struct page **pages;

	unsigned int i = 0, nid = dev_to_node(dev);



	order_mask &= (2U << MAX_ORDER) - 1;

	order_mask &= GENMASK(MAX_ORDER - 1, 0);

	if (!order_mask)

		return NULL;
@@ -756,7 +756,7 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev, 
		 * than a necessity, hence using __GFP_NORETRY until

		 * falling back to minimum-order allocations.

		 */

		for (order_mask &= (2U << __fls(count)) - 1;

		for (order_mask &= GENMASK(__fls(count), 0);

		     order_mask; order_mask &= ~order_size) {

			unsigned int order = __fls(order_mask);

			gfp_t alloc_flags = gfp;