From 61883d3c32418f16e35e030ca0cfd5d2de95a649 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Wed, 15 Mar 2023 14:31:32 +0300
Subject: [PATCH] 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: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
drivers/iommu/dma-iommu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 99b2646cb5c7a..ac996fd6bd9c2 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -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;
--
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