[PATCH 5/5] mm: nommu: Pass a pointer to virt_to_page()

Linus Walleij
2022-06-30T08:43:58Z

Functions that work on a pointer to virtual memory such as
virt_to_pfn() and users of that function such as
virt_to_page() are supposed to pass a pointer to virtual
memory, ideally a (void *) or other pointer. However since
many architectures implement virt_to_pfn() as a macro,
this function becomes polymorphic and accepts both a
(unsigned long) and a (void *).

If we instead implement a proper virt_to_pfn(void *addr)
function the following happens (occurred on arch/arm):

mm/nommu.c: In function 'free_page_series':
mm/nommu.c:501:50: warning: passing argument 1 of 'virt_to_pfn'
makes pointer from integer without a cast [-Wint-conversion]
struct page *page = virt_to_page(from);

Fix this with an explicit cast.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
mm/nommu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index 9d7afc2d959e..e819cbc21b39 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -500,7 +500,7 @@ static void delete_nommu_region(struct vm_region *region)
static void free_page_series(unsigned long from, unsigned long to)
{
for (; from < to; from += PAGE_SIZE) {
- struct page *page = virt_to_page(from);
+ struct page *page = virt_to_page((void *)from);

atomic_long_dec(&mmap_pages_allocated);
put_page(page);
--
2.36.1