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

I have reverted that commit for today.

-- 
Cheers,
Stephen Rothwell