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Diffstat (limited to '')
| -rw-r--r-- | mm/page_isolation.c | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/mm/page_isolation.c b/mm/page_isolation.c new file mode 100644 index 000000000..abbf42214 --- /dev/null +++ b/mm/page_isolation.c @@ -0,0 +1,313 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/mm/page_isolation.c + */ + +#include <linux/mm.h> +#include <linux/page-isolation.h> +#include <linux/pageblock-flags.h> +#include <linux/memory.h> +#include <linux/hugetlb.h> +#include <linux/page_owner.h> +#include <linux/migrate.h> +#include "internal.h" + +#define CREATE_TRACE_POINTS +#include <trace/events/page_isolation.h> + +static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags) +{ + struct zone *zone = page_zone(page); + struct page *unmovable; + unsigned long flags; + + spin_lock_irqsave(&zone->lock, flags); + + /* + * We assume the caller intended to SET migrate type to isolate. + * If it is already set, then someone else must have raced and + * set it before us. + */ + if (is_migrate_isolate_page(page)) { + spin_unlock_irqrestore(&zone->lock, flags); + return -EBUSY; + } + + /* + * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. + * We just check MOVABLE pages. + */ + unmovable = has_unmovable_pages(zone, page, migratetype, isol_flags); + if (!unmovable) { + unsigned long nr_pages; + int mt = get_pageblock_migratetype(page); + + set_pageblock_migratetype(page, MIGRATE_ISOLATE); + zone->nr_isolate_pageblock++; + nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE, + NULL); + + __mod_zone_freepage_state(zone, -nr_pages, mt); + spin_unlock_irqrestore(&zone->lock, flags); + drain_all_pages(zone); + return 0; + } + + spin_unlock_irqrestore(&zone->lock, flags); + if (isol_flags & REPORT_FAILURE) { + /* + * printk() with zone->lock held will likely trigger a + * lockdep splat, so defer it here. + */ + dump_page(unmovable, "unmovable page"); + } + + return -EBUSY; +} + +static void unset_migratetype_isolate(struct page *page, unsigned migratetype) +{ + struct zone *zone; + unsigned long flags, nr_pages; + bool isolated_page = false; + unsigned int order; + unsigned long pfn, buddy_pfn; + struct page *buddy; + + zone = page_zone(page); + spin_lock_irqsave(&zone->lock, flags); + if (!is_migrate_isolate_page(page)) + 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 = buddy_order(page); + if (order >= pageblock_order) { + pfn = page_to_pfn(page); + buddy_pfn = __find_buddy_pfn(pfn, order); + buddy = page + (buddy_pfn - pfn); + + if (pfn_valid_within(buddy_pfn) && + !is_migrate_isolate_page(buddy)) { + __isolate_free_page(page, order); + isolated_page = true; + } + } + } + + /* + * 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. + * + * We didn't actually touch any of the isolated pages, so place them + * to the tail of the freelist. This is an optimization for memory + * onlining - just onlined memory won't immediately be considered for + * allocation. + */ + if (!isolated_page) { + nr_pages = move_freepages_block(zone, page, migratetype, NULL); + __mod_zone_freepage_state(zone, nr_pages, migratetype); + } + set_pageblock_migratetype(page, migratetype); + if (isolated_page) + __putback_isolated_page(page, order, migratetype); + zone->nr_isolate_pageblock--; +out: + spin_unlock_irqrestore(&zone->lock, flags); +} + +static inline struct page * +__first_valid_page(unsigned long pfn, unsigned long nr_pages) +{ + int i; + + for (i = 0; i < nr_pages; i++) { + struct page *page; + + page = pfn_to_online_page(pfn + i); + if (!page) + continue; + return page; + } + return NULL; +} + +/** + * 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. + * start_pfn/end_pfn must be aligned to pageblock_order. + * @migratetype: Migrate type to set in error recovery. + * @flags: The following flags are allowed (they can be combined in + * a bit mask) + * MEMORY_OFFLINE - isolate to offline (!allocate) memory + * e.g., skip over PageHWPoison() pages + * and PageOffline() pages. + * REPORT_FAILURE - report details about the failure to + * isolate the range + * + * 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. If specified range includes migrate types + * other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all + * pages in the range finally, the caller have to free all pages in the range. + * test_page_isolated() can be used for test it. + * + * There is no high level synchronization mechanism that prevents two threads + * from trying to isolate overlapping ranges. If this happens, one thread + * will notice pageblocks in the overlapping range already set to isolate. + * This happens in set_migratetype_isolate, and set_migratetype_isolate + * returns an error. We then clean up by restoring the migration type on + * pageblocks we may have modified and return -EBUSY to caller. This + * prevents two threads from simultaneously working on overlapping ranges. + * + * Please note that there is no strong synchronization with the page allocator + * either. Pages might be freed while their page blocks are marked ISOLATED. + * In some cases pages might still end up on pcp lists and that would allow + * for their allocation even when they are in fact isolated already. Depending + * on how strong of a guarantee the caller needs drain_all_pages might be needed + * (e.g. __offline_pages will need to call it after check for isolated range for + * a next retry). + * + * Return: 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, int flags) +{ + unsigned long pfn; + unsigned long undo_pfn; + struct page *page; + + BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); + BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); + + for (pfn = start_pfn; + pfn < end_pfn; + pfn += pageblock_nr_pages) { + page = __first_valid_page(pfn, pageblock_nr_pages); + if (page) { + if (set_migratetype_isolate(page, migratetype, flags)) { + undo_pfn = pfn; + goto undo; + } + } + } + return 0; +undo: + for (pfn = start_pfn; + pfn < undo_pfn; + pfn += pageblock_nr_pages) { + struct page *page = pfn_to_online_page(pfn); + if (!page) + continue; + unset_migratetype_isolate(page, migratetype); + } + + return -EBUSY; +} + +/* + * Make isolated pages available again. + */ +void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, + unsigned migratetype) +{ + unsigned long pfn; + struct page *page; + + BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); + BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); + + for (pfn = start_pfn; + pfn < end_pfn; + pfn += pageblock_nr_pages) { + page = __first_valid_page(pfn, pageblock_nr_pages); + if (!page || !is_migrate_isolate_page(page)) + continue; + unset_migratetype_isolate(page, migratetype); + } +} +/* + * 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 the last tested pfn. + */ +static unsigned long +__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, + int flags) +{ + struct page *page; + + while (pfn < end_pfn) { + if (!pfn_valid_within(pfn)) { + pfn++; + continue; + } + page = pfn_to_page(pfn); + if (PageBuddy(page)) + /* + * If the page is on a free list, it has to be on + * the correct MIGRATE_ISOLATE freelist. There is no + * simple way to verify that as VM_BUG_ON(), though. + */ + pfn += 1 << buddy_order(page); + else if ((flags & MEMORY_OFFLINE) && PageHWPoison(page)) + /* A HWPoisoned page cannot be also PageBuddy */ + pfn++; + else if ((flags & MEMORY_OFFLINE) && PageOffline(page) && + !page_count(page)) + /* + * The responsible driver agreed to skip PageOffline() + * pages when offlining memory by dropping its + * reference in MEM_GOING_OFFLINE. + */ + pfn++; + else + break; + } + + return pfn; +} + +/* Caller should ensure that requested range is in a single zone */ +int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, + int isol_flags) +{ + unsigned long pfn, flags; + struct page *page; + struct zone *zone; + + /* + * 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 && !is_migrate_isolate_page(page)) + 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); + pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, isol_flags); + spin_unlock_irqrestore(&zone->lock, flags); + + trace_test_pages_isolated(start_pfn, end_pfn, pfn); + + return pfn < end_pfn ? -EBUSY : 0; +} |