Subject: [PATCH 1/3] iommu/io-pgtable-arm: Use consistent sizes for page allocation and freeing

From: Mostafa Saleh <[email-masked]>
Date: Wed, 13 May 2026 21:52:01 +0000

At the moment we use alloc_size to allocate memory but then there
is a logical error where we just size in the error and free path,
which might be smaller.
Also we size to do DMA-API operations, which is OK, but confusing.

Instead of this error-prone handling, just set size to alloc_size
and use it everywhere.

Signed-off-by: Mostafa Saleh <[email-masked]>
---
 drivers/iommu/io-pgtable-arm.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 0208e5897c29..0cbe545c491d 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -253,7 +253,6 @@ static void *__arm_lpae_alloc_pages(size_t size, gfp_t gfp,
 				    void *cookie)
 {
 	struct device *dev = cfg->iommu_dev;
-	size_t alloc_size;
 	dma_addr_t dma;
 	void *pages;
 
@@ -261,12 +260,11 @@ static void *__arm_lpae_alloc_pages(size_t size, gfp_t gfp,
 	 * For very small starting-level translation tables the HW requires a
 	 * minimum alignment of at least 64 to cover all cases.
 	 */
-	alloc_size = max(size, 64);
+	size = max(size, 64);
 	if (cfg->alloc)
-		pages = cfg->alloc(cookie, alloc_size, gfp);
+		pages = cfg->alloc(cookie, size, gfp);
 	else
-		pages = iommu_alloc_pages_node_sz(dev_to_node(dev), gfp,
-						  alloc_size);
+		pages = iommu_alloc_pages_node_sz(dev_to_node(dev), gfp, size);
 
 	if (!pages)
 		return NULL;
@@ -303,6 +301,9 @@ static void __arm_lpae_free_pages(void *pages, size_t size,
 				  struct io_pgtable_cfg *cfg,
 				  void *cookie)
 {
+	/* See __arm_lpae_alloc_pages(). */
+	size = max(size, 64);
+
 	if (!cfg->coherent_walk)
 		dma_unmap_single(cfg->iommu_dev, __arm_lpae_dma_addr(pages),
 				 size, DMA_TO_DEVICE);
-- 
2.54.0.563.g4f69b47b94-goog