mm: nommu: pass a pointer to virt_to_page()

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.

Link: https://lkml.kernel.org/r/20220630084124.691207-6-linus.walleij@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/nommu.c b/mm/nommu.c
index 9d7afc2d959e4ca99e305c0439991cccdf5ba194..e819cbc21b396b6ac00f6485c5fb7bc2c8b87649 100644 (file)
--- 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);