Re: linux-next: build warning after merge of the mm-unstable tree

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 9 May 2025 19:43:36 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:

> Hi all,
> 
> After merging the mm-unstable tree, today's linux-next build (powerpc64
> allnoconfig) produced this warning:
> 
> In file included from include/vdso/const.h:5,
>                  from include/linux/const.h:4,
>                  from include/linux/bits.h:5,
>                  from include/linux/ratelimit_types.h:5,
>                  from include/linux/printk.h:9,
>                  from include/asm-generic/bug.h:22,
>                  from arch/powerpc/include/asm/bug.h:116,
>                  from include/linux/bug.h:5,
>                  from include/linux/mmdebug.h:5,
>                  from include/linux/mm.h:6,
>                  from mm/sparse.c:5:
> mm/sparse.c: In function 'usemap_size':
> include/linux/mmzone.h:1815:15: warning: left shift count is negative [-Wshift-count-negative]
>  1815 |         ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
>       |               ^~
> include/uapi/linux/const.h:51:40: note: in definition of macro '__KERNEL_DIV_ROUND_UP'
>    51 | #define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
>       |                                        ^
> mm/sparse.c:301:16: note: in expansion of macro 'BITS_TO_LONGS'
>   301 |         return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
>       |                ^~~~~~~~~~~~~
> mm/sparse.c:301:30: note: in expansion of macro 'SECTION_BLOCKFLAGS_BITS'
>   301 |         return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
>       |                              ^~~~~~~~~~~~~~~~~~~~~~~
> 
> Probably introduced by commit
> 
>  ("mm: add CONFIG_PAGE_BLOCK_ORDER to select page block order")
> 

Yes, thanks, I'll drop this version of the patch.