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;
+}