[PATCH v3 04/10] iommu/dma: Use the gfp parameter in __iommu_dma_alloc_noncontiguous()

Jason Gunthorpe
2023-01-23T20:36:17Z

This function does an allocation of a buffer to return to the caller and
then goes on to allocate some internal memory, eg the scatterlist and
IOPTEs.

Instead of hard wiring GFP_KERNEL and a wrong GFP_ATOMIC, continue to use
the passed in gfp flags for all of the allocations. Clear the zone and
policy bits that are only relevant for the buffer allocation before
re-using them for internal allocations.

Auditing says this is never called from an atomic context, so the
GFP_ATOMIC is the incorrect flag.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/iommu/dma-iommu.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 72cfa24503b8bc..c99e4bc55d8cb0 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -822,7 +822,14 @@ static struct page **__iommu_dma_alloc_noncontiguous(struct device *dev,
if (!iova)
goto out_free_pages;

- if (sg_alloc_table_from_pages(sgt, pages, count, 0, size, GFP_KERNEL))
+ /*
+ * Remove the zone/policy flags from the GFP - these are applied to the
+ * __iommu_dma_alloc_pages() but are not used for the supporting
+ * internal allocations that follow.
+ */
+ gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM | __GFP_COMP);
+
+ if (sg_alloc_table_from_pages(sgt, pages, count, 0, size, gfp))
goto out_free_iova;

if (!(ioprot & IOMMU_CACHE)) {
@@ -834,7 +841,7 @@ static struct page **__iommu_dma_alloc_noncontiguous(struct device *dev,
}

ret = iommu_map_sg(domain, iova, sgt->sgl, sgt->orig_nents, ioprot,
- GFP_ATOMIC);
+ gfp);
if (ret < 0 || ret < size)
goto out_free_sg;

--
2.39.0