From a5d76b54a3f3a40385d7f76069a2feac9f1bad63 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Tue, 16 Oct 2007 01:26:11 -0700 Subject: memory unplug: page isolation Implement generic chunk-of-pages isolation method by using page grouping ops. This patch add MIGRATE_ISOLATE to MIGRATE_TYPES. By this - MIGRATE_TYPES increases. - bitmap for migratetype is enlarged. pages of MIGRATE_ISOLATE migratetype will not be allocated even if it is free. By this, you can isolated *freed* pages from users. How-to-free pages is not a purpose of this patch. You may use reclaim and migrate codes to free pages. If start_isolate_page_range(start,end) is called, - migratetype of the range turns to be MIGRATE_ISOLATE if its type is MIGRATE_MOVABLE. (*) this check can be updated if other memory reclaiming works make progress. - MIGRATE_ISOLATE is not on migratetype fallback list. - All free pages and will-be-freed pages are isolated. To check all pages in the range are isolated or not, use test_pages_isolated(), To cancel isolation, use undo_isolate_page_range(). Changes V6 -> V7 - removed unnecessary #ifdef There are HOLES_IN_ZONE handling codes...I'm glad if we can remove them.. Signed-off-by: Yasunori Goto Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_isolation.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 138 insertions(+) create mode 100644 mm/page_isolation.c (limited to 'mm/page_isolation.c') diff --git a/mm/page_isolation.c b/mm/page_isolation.c new file mode 100644 index 000000000000..8f92a29695cc --- /dev/null +++ b/mm/page_isolation.c @@ -0,0 +1,138 @@ +/* + * linux/mm/page_isolation.c + */ + +#include +#include +#include +#include +#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_flags(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_flags(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; +} -- cgit v1.2.3-59-g8ed1b