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

Omar Sandoval
2018-07-25T23:18:26Z

On Mon, Jul 23, 2018 at 07:42:31PM +1000, Stephen Rothwell wrote:
> Hi Andrew,
>
> After merging the akpm tree, today's linux-next build (sparc (32 bit)
> defconfig) failed like this:
>
> In file included from kernel/crash_core.c:9:0:
> kernel/crash_core.c: In function 'crash_save_vmcoreinfo_init':
> include/linux/crash_core.h:44:66: error: lvalue required as unary '&' operand
> vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)&name)
> ^
> kernel/crash_core.c:404:2: note: in expansion of macro 'VMCOREINFO_SYMBOL'
> VMCOREINFO_SYMBOL(swapper_pg_dir);
> ^~~~~~~~~~~~~~~~~
>
> Caused by commit
>
> e527c514996a ("proc/kcore: add vmcoreinfo note to /proc/kcore")
>
> It seems that sparc does not declare swapper_pg_dir for 32 but builds,
> they just define it to be NULL. As do some others:
>
> $ git grep -w 'define.*swapper_pg_dir'
> arch/arm/include/asm/pgtable-nommu.h:#define swapper_pg_dir ((pgd_t *) 0)
> arch/c6x/include/asm/pgtable.h:#define swapper_pg_dir ((pgd_t *) 0)
> arch/h8300/include/asm/pgtable.h:#define swapper_pg_dir ((pgd_t *) 0)
> arch/m68k/include/asm/pgtable_no.h:#define swapper_pg_dir ((pgd_t *) 0)
> arch/microblaze/include/asm/pgtable.h:#define swapper_pg_dir ((pgd_t *) NULL)
> arch/sparc/include/asm/pgtable_32.h:#define swapper_pg_dir NULL
> arch/xtensa/include/asm/pgtable.h:# define swapper_pg_dir NULL

Mm, I wrongly assumed that this would only be the case for !MMU. Looks
like it's always either NULL or an array, so VMCOREINFO_SYMBOL_ARRAY
should work here. I'll send a new version.