[PATCH 4/5] mm: gup: Pass a pointer to virt_to_page()

Linus Walleij
2022-06-30T08:43:57Z

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/gup.c: In function '__get_user_pages_locked':
mm/gup.c:1599:49: warning: passing argument 1 of 'virt_to_pfn'
makes pointer from integer without a cast [-Wint-conversion]
pages[i] = virt_to_page(start);

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/gup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/gup.c b/mm/gup.c
index 551264407624..543c68da65f1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1672,7 +1672,7 @@ static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start,
goto finish_or_fault;

if (pages) {
- pages[i] = virt_to_page(start);
+ pages[i] = virt_to_page((void *)start);
if (pages[i])
get_page(pages[i]);
}
--
2.36.1