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

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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: 06c375053c ("iommu/vt-d: add wrapper functions for page allocations")
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v4-c8663abbb606+3f7-iommu_pages_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Jason Gunthorpe 2025-04-08 13:53:52 -03:00 committed by Joerg Roedel
parent 8360c03dd9
commit c11a1a4792
1 changed files with 7 additions and 5 deletions
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12
drivers/iommu/iommu-pages.h
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@ -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);
}
}