/* * linux/mm/page_isolation.c */ #include <stddef.h> #include <linux/mm.h> #include <linux/page-isolation.h> #include <linux/pageblock-flags.h> #include "internal.h" static inline struct page * __first_valid_page(unsigned long pfn, unsigned long nr_pages) { int i; for (i = 0; i < nr_pages; i++) if (pfn_valid_within(pfn + i)) break; if (unlikely(i == nr_pages)) return NULL; return pfn_to_page(pfn + i); } /* * start_isolate_page_range() -- make page-allocation-type of range of pages * to be MIGRATE_ISOLATE. * @start_pfn: The lower PFN of the range to be isolated. * @end_pfn: The upper PFN of the range to be isolated. * * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in * the range will never be allocated. Any free pages and pages freed in the * future will not be allocated again. * * start_pfn/end_pfn must be aligned to pageblock_order. * Returns 0 on success and -EBUSY if any part of range cannot be isolated. */ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) { unsigned long pfn; unsigned long undo_pfn; struct page *page; BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { page = __first_valid_page(pfn, pageblock_nr_pages); if (page && set_migratetype_isolate(page)) { undo_pfn = pfn; goto undo; } } return 0; undo: for (pfn = start_pfn; pfn < undo_pfn; pfn += pageblock_nr_pages) unset_migratetype_isolate(pfn_to_page(pfn)); return -EBUSY; } /* * Make isolated pages available again. */ int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn) { unsigned long pfn; struct page *page; BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { page = __first_valid_page(pfn, pageblock_nr_pages); if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE) continue; unset_migratetype_isolate(page); } return 0; } /* * Test all pages in the range is free(means isolated) or not. * all pages in [start_pfn...end_pfn) must be in the same zone. * zone->lock must be held before call this. * * Returns 0 if all pages in the range is isolated. */ static int __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn) { struct page *page; while (pfn < end_pfn) { if (!pfn_valid_within(pfn)) { pfn++; continue; } page = pfn_to_page(pfn); if (PageBuddy(page)) pfn += 1 << page_order(page); else if (page_count(page) == 0 && page_private(page) == MIGRATE_ISOLATE) pfn += 1; else break; } if (pfn < end_pfn) return 0; return 1; } int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) { unsigned long pfn; struct page *page; pfn = start_pfn; /* * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page * is not aligned to pageblock_nr_pages. * Then we just check pagetype fist. */ for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { page = __first_valid_page(pfn, pageblock_nr_pages); if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE) break; } if (pfn < end_pfn) return -EBUSY; /* Check all pages are free or Marked as ISOLATED */ if (__test_page_isolated_in_pageblock(start_pfn, end_pfn)) return 0; return -EBUSY; }