+ mm-nommu-pass-a-pointer-to-virt_to_page.patch added to mm-unstable branch

+ mm-nommu-pass-a-pointer-to-virt_to_page.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: nommu: pass a pointer to virt_to_page()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-nommu-pass-a-pointer-to-virt_to_page.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-nommu-pass-a-pointer-to-virt_to_page.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Linus Walleij <linus.walleij@linaro.org>
Subject: mm: nommu: pass a pointer to virt_to_page()
Date: Thu, 30 Jun 2022 10:41:24 +0200

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>
---

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

--- a/mm/nommu.c~mm-nommu-pass-a-pointer-to-virt_to_page
+++ a/mm/nommu.c
@@ -499,7 +499,7 @@ static void delete_nommu_region(struct v
 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);
_

Patches currently in -mm which might be from linus.walleij@linaro.org are

lib-test_free_pagesc-pass-a-pointer-to-virt_to_page.patch
mm-highmem-pass-a-pointer-to-virt_to_page.patch
mm-kfence-pass-a-pointer-to-virt_to_page.patch
mm-gup-pass-a-pointer-to-virt_to_page.patch
mm-nommu-pass-a-pointer-to-virt_to_page.patch