From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- mm/page_isolation.c | 314 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 314 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 000000000..303c90879 --- /dev/null +++ b/mm/page_isolation.c @@ -0,0 +1,314 @@ +/* + * linux/mm/page_isolation.c + */ + +#include +#include +#include +#include +#include +#include "internal.h" + +int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages) +{ + struct zone *zone; + unsigned long flags, pfn; + struct memory_isolate_notify arg; + int notifier_ret; + int ret = -EBUSY; + + zone = page_zone(page); + + spin_lock_irqsave(&zone->lock, flags); + + pfn = page_to_pfn(page); + arg.start_pfn = pfn; + arg.nr_pages = pageblock_nr_pages; + arg.pages_found = 0; + + /* + * It may be possible to isolate a pageblock even if the + * migratetype is not MIGRATE_MOVABLE. The memory isolation + * notifier chain is used by balloon drivers to return the + * number of pages in a range that are held by the balloon + * driver to shrink memory. If all the pages are accounted for + * by balloons, are free, or on the LRU, isolation can continue. + * Later, for example, when memory hotplug notifier runs, these + * pages reported as "can be isolated" should be isolated(freed) + * by the balloon driver through the memory notifier chain. + */ + notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg); + notifier_ret = notifier_to_errno(notifier_ret); + if (notifier_ret) + goto out; + /* + * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. + * We just check MOVABLE pages. + */ + if (!has_unmovable_pages(zone, page, arg.pages_found, + skip_hwpoisoned_pages)) + ret = 0; + + /* + * immobile means "not-on-lru" paes. If immobile is larger than + * removable-by-driver pages reported by notifier, we'll fail. + */ + +out: + if (!ret) { + unsigned long nr_pages; + int migratetype = get_pageblock_migratetype(page); + + set_pageblock_migratetype(page, MIGRATE_ISOLATE); + zone->nr_isolate_pageblock++; + nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE); + + __mod_zone_freepage_state(zone, -nr_pages, migratetype); + } + + spin_unlock_irqrestore(&zone->lock, flags); + if (!ret) + drain_all_pages(zone); + return ret; +} + +void unset_migratetype_isolate(struct page *page, unsigned migratetype) +{ + struct zone *zone; + unsigned long flags, nr_pages; + struct page *isolated_page = NULL; + unsigned int order; + unsigned long page_idx, buddy_idx; + struct page *buddy; + + zone = page_zone(page); + spin_lock_irqsave(&zone->lock, flags); + if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE) + goto out; + + /* + * Because freepage with more than pageblock_order on isolated + * pageblock is restricted to merge due to freepage counting problem, + * it is possible that there is free buddy page. + * move_freepages_block() doesn't care of merge so we need other + * approach in order to merge them. Isolation and free will make + * these pages to be merged. + */ + if (PageBuddy(page)) { + order = page_order(page); + if (order >= pageblock_order) { + page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1); + buddy_idx = __find_buddy_index(page_idx, order); + buddy = page + (buddy_idx - page_idx); + + if (pfn_valid_within(page_to_pfn(buddy)) && + !is_migrate_isolate_page(buddy)) { + __isolate_free_page(page, order); + kernel_map_pages(page, (1 << order), 1); + set_page_refcounted(page); + isolated_page = page; + } + } + } + + /* + * If we isolate freepage with more than pageblock_order, there + * should be no freepage in the range, so we could avoid costly + * pageblock scanning for freepage moving. + */ + if (!isolated_page) { + nr_pages = move_freepages_block(zone, page, migratetype); + __mod_zone_freepage_state(zone, nr_pages, migratetype); + } + set_pageblock_migratetype(page, migratetype); + zone->nr_isolate_pageblock--; +out: + spin_unlock_irqrestore(&zone->lock, flags); + if (isolated_page) + __free_pages(isolated_page, order); +} + +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. + * @migratetype: migrate type to set in error recovery. + * + * 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 migratetype, bool skip_hwpoisoned_pages) +{ + 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, skip_hwpoisoned_pages)) { + 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), migratetype); + + return -EBUSY; +} + +/* + * Make isolated pages available again. + */ +int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, + unsigned migratetype) +{ + 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, migratetype); + } + 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 1 if all pages in the range are isolated. + */ +static int +__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, + bool skip_hwpoisoned_pages) +{ + struct page *page; + + while (pfn < end_pfn) { + if (!pfn_valid_within(pfn)) { + pfn++; + continue; + } + page = pfn_to_page(pfn); + if (PageBuddy(page)) { + /* + * If race between isolatation and allocation happens, + * some free pages could be in MIGRATE_MOVABLE list + * although pageblock's migratation type of the page + * is MIGRATE_ISOLATE. Catch it and move the page into + * MIGRATE_ISOLATE list. + */ + if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) { + struct page *end_page; + + end_page = page + (1 << page_order(page)) - 1; + move_freepages(page_zone(page), page, end_page, + MIGRATE_ISOLATE); + } + pfn += 1 << page_order(page); + } + else if (page_count(page) == 0 && + get_freepage_migratetype(page) == MIGRATE_ISOLATE) + pfn += 1; + else if (skip_hwpoisoned_pages && PageHWPoison(page)) { + /* + * The HWPoisoned page may be not in buddy + * system, and page_count() is not 0. + */ + pfn++; + continue; + } + else + break; + } + if (pfn < end_pfn) + return 0; + return 1; +} + +int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, + bool skip_hwpoisoned_pages) +{ + unsigned long pfn, flags; + struct page *page; + struct zone *zone; + int ret; + + /* + * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages + * are not aligned to pageblock_nr_pages. + * Then we just check migratetype first. + */ + 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; + } + page = __first_valid_page(start_pfn, end_pfn - start_pfn); + if ((pfn < end_pfn) || !page) + return -EBUSY; + /* Check all pages are free or marked as ISOLATED */ + zone = page_zone(page); + spin_lock_irqsave(&zone->lock, flags); + ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn, + skip_hwpoisoned_pages); + spin_unlock_irqrestore(&zone->lock, flags); + return ret ? 0 : -EBUSY; +} + +struct page *alloc_migrate_target(struct page *page, unsigned long private, + int **resultp) +{ + gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE; + + /* + * TODO: allocate a destination hugepage from a nearest neighbor node, + * accordance with memory policy of the user process if possible. For + * now as a simple work-around, we use the next node for destination. + */ + if (PageHuge(page)) { + nodemask_t src = nodemask_of_node(page_to_nid(page)); + nodemask_t dst; + nodes_complement(dst, src); + return alloc_huge_page_node(page_hstate(compound_head(page)), + next_node(page_to_nid(page), dst)); + } + + if (PageHighMem(page)) + gfp_mask |= __GFP_HIGHMEM; + + return alloc_page(gfp_mask); +} -- cgit v1.2.3-54-g00ecf