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

Hi all,

After merging the akpm-current tree, today's linux-next build (arm multi_v7_defconfig) produced this warning:

fs/proc/task_mmu.c: In function 'pagemap_pmd_range':
fs/proc/task_mmu.c:1444:14: warning: unused variable 'migration' [-Wunused-variable]

 1444 |         bool migration = false;
      |              ^~~~~~~~~

Introduced by commit

78cff485ae77 ("fs-proc-task_mmuc-dont-read-mapcount-for-migration-entry-v4")

"migration" is only used when CONFIG_TRANSPARENT_HUGEPAGE is defined.

Cheers,
Stephen Rothwell