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- // 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);
- 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.
- * A call to drain_all_pages() after isolation can flush most of them. However
- * 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, further 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 *failed_pfn)
- {
- 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;
- if (failed_pfn)
- *failed_pfn = page_to_pfn(page);
- 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 *failed_pfn)
- {
- 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);
- if (pfn < end_pfn) {
- page_pinner_failure_detect(pfn_to_page(pfn));
- if (failed_pfn)
- *failed_pfn = pfn;
- return -EBUSY;
- }
- return 0;
- }
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