Re: linux-next: build warning after merge of the akpm-current tree

[Andrew Morton]

On Tue, 31 Mar 2020 19:56:12 +1100 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:

> Hi all,
> 
> After merging the akpm-current tree, today's linux-next build (i386
> defconfig) produced this warning:
> 
> mm/hugetlb.c: In function 'huge_pte_offset':
> cc1: warning: function may return address of local variable [-Wreturn-local-addr]
> mm/hugetlb.c:5361:14: note: declared here
>  5361 |  pud_t *pud, pud_entry;
>       |              ^~~~~~~~~
> cc1: warning: function may return address of local variable [-Wreturn-local-addr]
> mm/hugetlb.c:5360:14: note: declared here
>  5360 |  p4d_t *p4d, p4d_entry;
>       |              ^~~~~~~~~
> 
> Introduced by commit
> 
>   826ddc88e2cf ("mm/hugetlb: fix a addressing exception caused by huge_pte_offset")

I can reproduce this (i386 defconfig, gcc-7.2.0).

I can see no way in which this makes any sense.  Hopefully it's a gcc
bug but it's hard to see how it could have messed up this fairly simple
code.