On 07/19/2016 09:18 PM, Zhou Chengming wrote: > When CONFIG_SPARSEMEM_EXTREME is disabled, __section_nr can get > the section number with a subtraction directly. Does this actually *do* anything? It was a long time ago, but if I remember correctly, the entire loop in __section_nr() goes away because root_nr==NR_SECTION_ROOTS, so root_nr=1, and the compiler optimizes away the entire subtraction. So this basically adds an #ifdef and gets us nothing, although it makes the situation much more explicit. Perhaps the comment should say that this works *and* is efficient because the compiler can optimize all the extreme complexity away. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>