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iommu/dma: Remove broken huge page handling 

The attempt to handle huge page allocations was originally added since
the comments around stripping __GFP_COMP in other implementations were
nonsensical, and we naively assumed that split_huge_page() could simply
be called equivalently to split_page(). It turns out that this doesn't
actually work correctly, so just get rid of it - there's little point
going to the effort of allocating huge pages if we're only going to
split them anyway.

Reported-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/e287dbe69aa0933abafd97c80631940fd188ddd1.1599132844.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Robin Murphy 2020-09-03 12:34:04 +01:00 committed by Joerg Roedel
parent aae4c8e27b
commit 4604393ca0
1 changed files with 5 additions and 8 deletions
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13
drivers/iommu/dma-iommu.c
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@ -524,6 +524,9 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev,
/* IOMMU can map any pages, so himem can also be used here */
gfp |= __GFP_NOWARN | __GFP_HIGHMEM;
/* It makes no sense to muck about with huge pages */
gfp &= ~__GFP_COMP;
while (count) {
struct page *page = NULL;
unsigned int order_size;
@ -544,15 +547,9 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev,
page = alloc_pages_node(nid, alloc_flags, order);
if (!page)
continue;
if (!order)
break;
if (!PageCompound(page)) {
if (order)
split_page(page, order);
break;
} else if (!split_huge_page(page)) {
break;
}
__free_pages(page, order);
break;
}
if (!page) {
__iommu_dma_free_pages(pages, i);