Commit c11a1a47 authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Joerg Roedel
Browse files

iommu/pages: Make iommu_put_pages_list() work with high order allocations 



alloc_pages_node(, order) needs to be paired with __free_pages(, order) to
free all the allocated pages. For order != 0 the return from
alloc_pages_node() is just a page list, it hasn't been formed into a
folio.

However iommu_put_pages_list() just calls put_page() on the head page of
an allocation, which will end up leaking the tail pages if order != 0.

Fix this by using __GFP_COMP to create a high order folio and then always
use put_page() to free the full high order folio.

__iommu_free_account() can get the order of the allocation via
folio_order(), which corrects the accounting of high order allocations in
iommu_put_pages_list(). This is the same technique slub uses.

As far as I can tell, none of the places using high order allocations are
also using the free list, so this not a current bug.

Fixes: 06c37505 ("iommu/vt-d: add wrapper functions for page allocations")
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Tested-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Tested-by: default avatarAlejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v4-c8663abbb606+3f7-iommu_pages_jgg@nvidia.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 8360c03d

drivers/iommu/iommu-pages.h

+7 −5
Original line number Diff line number Diff line
@@ -38,8 +38,9 @@ static inline void __iommu_alloc_account(struct page *page, int order) 
 * @page: head struct page of the page.

 * @order: order of the page

 */

static inline void __iommu_free_account(struct page *page, int order)

static inline void __iommu_free_account(struct page *page)

{

	unsigned int order = folio_order(page_folio(page));

	const long pgcnt = 1l << order;



	mod_node_page_state(page_pgdat(page), NR_IOMMU_PAGES, -pgcnt);
@@ -57,7 +58,8 @@ static inline void __iommu_free_account(struct page *page, int order) 
 */

static inline void *iommu_alloc_pages_node(int nid, gfp_t gfp, int order)

{

	struct page *page = alloc_pages_node(nid, gfp | __GFP_ZERO, order);

	struct page *page =

		alloc_pages_node(nid, gfp | __GFP_ZERO | __GFP_COMP, order);



	if (unlikely(!page))

		return NULL;
@@ -115,8 +117,8 @@ static inline void iommu_free_pages(void *virt, int order) 
		return;



	page = virt_to_page(virt);

	__iommu_free_account(page, order);

	__free_pages(page, order);

	__iommu_free_account(page);

	put_page(page);

}



/**
@@ -143,7 +145,7 @@ static inline void iommu_put_pages_list(struct list_head *page) 
		struct page *p = list_entry(page->prev, struct page, lru);



		list_del(&p->lru);

		__iommu_free_account(p, 0);

		__iommu_free_account(p);

		put_page(p);

	}

}