Jaegeuk, > Thanks for your response. But which kind of pages are in the special > reserved and which are all-flags-cleared? The all-flags-cleared pages are mostly free pages in the buddy system. The pages with flag "buddy" are also free pages: the buddy system only marks the head pages of each order-2 free range with flag "buddy". The reserved pages come from many sources, they may be set for memory reserved for BIOS, memory holes, offlined memory, or used by some device drivers. Thanks, Fengguang -- 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>