Subject: linux-next: build failure after merge of the mm tree

From: Stephen Rothwell <[email-masked]>
Date: Tue, 22 Nov 2022 17:53:23 +1100

Hi all,

After merging the mm tree, today's linux-next build (x86_64 allmodconfig)
failed like this:

In file included from include/uapi/linux/posix_types.h:5,
                 from include/uapi/linux/types.h:14,
                 from include/linux/types.h:6,
                 from include/linux/kasan-checks.h:5,
                 from include/asm-generic/rwonce.h:26,
                 from ./arch/powerpc/include/generated/asm/rwonce.h:1,
                 from include/linux/compiler.h:247,
                 from include/linux/build_bug.h:5,
                 from include/linux/container_of.h:5,
                 from include/linux/list.h:5,
                 from mm/hugetlb.c:6:
mm/hugetlb.c: In function 'add_hugetlb_page':
include/linux/stddef.h:8:14: warning: passing argument 2 of 'set_page_private' makes integer from pointer without a cast [-Wint-conversion]
    8 | #define NULL ((void *)0)
      |              ^~~~~~~~~~~
      |              |
      |              void *
mm/hugetlb.c:1533:32: note: in expansion of macro 'NULL'
 1533 |         set_page_private(page, NULL);
      |                                ^~~~
In file included from include/linux/mmzone.h:21,
                 from include/linux/gfp.h:7,
                 from include/linux/mm.h:7,
                 from mm/hugetlb.c:8:
include/linux/mm_types.h:464:70: note: expected 'long unsigned int' but argument is of type 'void *'
  464 | static inline void set_page_private(struct page *page, unsigned long private)
      |                                                        ~~~~~~~~~~~~~~^~~~~~~

Caused by commit

  1f0d844bcc5b ("mm/hugetlb: stop using 0 as NULL pointer")

set_page_private() have taken an unsigned long as its second argument
since (at least) v5.8-rc1.  The cited bugzilla refers to next-20221121,
but even there:

$ git grep set_page_private next-20221121:include/linux/mm_types.h
next-20221121:include/linux/mm_types.h:static inline void set_page_private(struct page *page, unsigned long private)

In fact the bugzilla refers to mm/hugetlb.c line 1531.  In next-20221121
that is:

        folio_change_private(folio, 0);

I have reverted that commit for today.  Please take more care :-(

-- 
Cheers,
Stephen Rothwell