Without CONFIG_SYSCTL, the compiler warns about a few unused functions:
mm/compaction.c:3076:12: error: 'proc_dointvec_minmax_warn_RT_change' defined but not used [-Werror=unused-function]
mm/compaction.c:2780:12: error: 'sysctl_compaction_handler' defined but not used [-Werror=unused-function]
mm/compaction.c:2750:12: error: 'compaction_proactiveness_sysctl_handler' defined but not used [-Werror=unused-function]
The #ifdef is actually not necessary here, as the alternative
register_sysctl_init() stub function does not use its argument, which
lets the compiler drop the rest implicitly, while avoiding the warning.
Fixes: c521126610c3 ("mm: compaction: move compaction sysctl to its own file") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>