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

[Christophe Leroy]

Nick,

Le 12/05/2021 à 07:33, Stephen Rothwell a écrit :
> Hi all,
>
> After merging the akpm-current tree, today's linux-next build (powerpc
> ppc64_defconfig) failed like this:
>
> In file included from arch/powerpc/include/asm/book3s/64/mmu-hash.h:20,
>                   from arch/powerpc/include/asm/book3s/64/mmu.h:31,
>                   from arch/powerpc/include/asm/mmu.h:402,
>                   from arch/powerpc/include/asm/lppaca.h:46,
>                   from arch/powerpc/include/asm/paca.h:17,
>                   from arch/powerpc/include/asm/current.h:13,
>                   from include/linux/thread_info.h:22,
>                   from include/asm-generic/preempt.h:5,
>                   from ./arch/powerpc/include/generated/asm/preempt.h:1,
>                   from include/linux/preempt.h:78,
>                   from include/linux/spinlock.h:51,
>                   from include/linux/vmalloc.h:5,
>                   from mm/ioremap.c:9:
> arch/powerpc/include/asm/book3s/64/pgtable.h:246:21: error: initializer element is not constant
>    246 | #define PGDIR_SHIFT (PUD_SHIFT + PUD_INDEX_SIZE)
>        |                     ^
> include/asm-generic/pgtable-nop4d.h:11:20: note: in expansion of macro 'PGDIR_SHIFT'
>     11 | #define P4D_SHIFT  PGDIR_SHIFT
>        |                    ^~~~~~~~~~~
> mm/ioremap.c:19:60: note: in expansion of macro 'P4D_SHIFT'
>     19 | static unsigned int __ro_after_init iomap_max_page_shift = P4D_SHIFT;
>        |                                                            ^~~~~~~~~

Argh ....

I'm still not used to CAPITAL_NAMES defines not being constant ....

So we need to initialise this from some init function that runs before parse_early_param()

Nick, any idea ?

> Caused by commit
>
>    9054fd6cce6c ("mm/ioremap: fix iomap_max_page_shift")
>
> I have reverted that commit for today.