[PATCH v2 5/5] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact[_nid]

Miaohe Lin
2021-09-02T12:12:46Z

Don't use with __GFP_HIGHMEM because page_address() cannot represent
highmem pages without kmap(). Newly allocated pages would leak as
page_address() will return NULL for highmem pages here. But It works
now because the callers do not specify __GFP_HIGHMEM now.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/page_alloc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9c09dcb24149..e1d0e27d005a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5614,8 +5614,8 @@ void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
unsigned int order = get_order(size);
unsigned long addr;

- if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
- gfp_mask &= ~__GFP_COMP;
+ if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
+ gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);

addr = __get_free_pages(gfp_mask, order);
return make_alloc_exact(addr, order, size);
@@ -5639,8 +5639,8 @@ void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
unsigned int order = get_order(size);
struct page *p;

- if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
- gfp_mask &= ~__GFP_COMP;
+ if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
+ gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);

p = alloc_pages_node(nid, gfp_mask, order);
if (!p)
--
2.23.0