99 		 * because another CPU can free compound page.  in has_unmovable_pages()
222 	 * it is possible that there is free buddy page.  in unset_migratetype_isolate()
224 	 * approach in order to merge them. Isolation and free will make  in unset_migratetype_isolate()
235 				 * Isolating a free page in an isolated pageblock  in unset_migratetype_isolate()
284  * within a free or in-use page.
293  * Free and in-use pages can be as big as MAX_PAGE_ORDER and contain more than one
295  * time, free page accounting can go wrong. For example, in the case of
300  * When either pageblock is isolated, if it is a free page, the page is not
302  * in-use page and freed later, __free_one_page() does not split the free page
303  * either. The function handles this by splitting the free page or migrating
304  * the in-use page then splitting the free page.
326 	 * free or in-use page. Also make sure all to-be-isolated pageblocks  in isolate_single_pageblock()
347 	 * a free or in-use page across boundary_pfn:  in isolate_single_pageblock()
372 		 * free pages in [start_pfn, boundary_pfn), its head page will  in isolate_single_pageblock()
379 				/* free page changed before split, check it again */  in isolate_single_pageblock()
388 		 * migrate compound pages then let the free page handling code  in isolate_single_pageblock()
426 				 * pages to be added into separate migratetype free  in isolate_single_pageblock()
441 				 * be split into separate migratetype free lists  in isolate_single_pageblock()
450 				 * reset pfn to the head of the free page, so  in isolate_single_pageblock()
451 				 * that the free page handling code above can split  in isolate_single_pageblock()
452 				 * the free page to the right migratetype list.  in isolate_single_pageblock()
456 				 * freed, the free page order is not. Use pfn within  in isolate_single_pageblock()
457 				 * the range to find the head of the free page.  in isolate_single_pageblock()
462 					/* stop if we cannot find the free page */  in isolate_single_pageblock()
499  * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
500  * the range will never be allocated. Any free pages and pages freed in the
503  * pages in the range finally, the caller have to free all pages in the range.
601  * Test all pages in the range is free(means isolated) or not.
617 			 * If the page is on a free list, it has to be on  in __test_page_isolated_in_pageblock()
646  * This tests if all in the specified range are free.
649  * poisoned and offlined pages free as well.
664 	 * Note: pageblock_nr_pages != MAX_PAGE_ORDER. Then, chunks of free  in test_pages_isolated()
679 	/* Check all pages are free or marked as ISOLATED */  in test_pages_isolated()