On Sun, 17 May 2020 23:47:18 +0200 Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx> wrote:
> We can cleanup code a little by call detach_page_private here.
>
> ...
>
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -804,10 +804,7 @@ static int __buffer_migrate_page(struct address_space *mapping,
> if (rc != MIGRATEPAGE_SUCCESS)
> goto unlock_buffers;
>
> - ClearPagePrivate(page);
> - set_page_private(newpage, page_private(page));
> - set_page_private(page, 0);
> - put_page(page);
> + set_page_private(newpage, detach_page_private(page));
> get_page(newpage);
>
> bh = head;
mm/migrate.c: In function '__buffer_migrate_page':
./include/linux/mm_types.h:243:52: warning: assignment makes integer from pointer without a cast [-Wint-conversion]
#define set_page_private(page, v) ((page)->private = (v))
^
mm/migrate.c:800:2: note: in expansion of macro 'set_page_private'
set_page_private(newpage, detach_page_private(page));
^~~~~~~~~~~~~~~~
The fact that set_page_private(detach_page_private()) generates a type
mismatch warning seems deeply wrong, surely.
Please let's get the types sorted out - either unsigned long or void *,
not half-one and half-the other. Whatever needs the least typecasting
at callsites, I suggest.
And can we please implement set_page_private() and page_private() with
inlined C code? There is no need for these to be macros.
