Split page table lock for PTE tables is enabled compile-time if
CONFIG_SPLIT_PTLOCK_CPUS (usually 4) is less or equal to NR_CPUS.
-If split lock is disabled, all tables guaded by mm->page_table_lock.
+If split lock is disabled, all tables are guarded by mm->page_table_lock.
Split page table lock for PMD tables is enabled, if it's enabled for PTE
tables and the architecture supports it (see below).