v4.19.13 snapshot.
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
new file mode 100644
index 0000000..43e0856
--- /dev/null
+++ b/mm/page_isolation.c
@@ -0,0 +1,315 @@
+// 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,
+ 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);
+
+ /*
+ * 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. Return -EBUSY
+ */
+ if (is_migrate_isolate_page(page))
+ goto out;
+
+ 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, migratetype,
+ skip_hwpoisoned_pages))
+ ret = 0;
+
+ /*
+ * immobile means "not-on-lru" pages. If immobile is larger than
+ * removable-by-driver pages reported by notifier, we'll fail.
+ */
+
+out:
+ if (!ret) {
+ 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);
+ if (!ret)
+ drain_all_pages(zone);
+ return ret;
+}
+
+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 = page_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.
+ */
+ 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);
+ zone->nr_isolate_pageblock--;
+out:
+ spin_unlock_irqrestore(&zone->lock, flags);
+ if (isolated_page) {
+ post_alloc_hook(page, order, __GFP_MOVABLE);
+ __free_pages(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++) {
+ struct page *page;
+
+ if (!pfn_valid_within(pfn + i))
+ continue;
+ 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.
+ * @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.
+ * Return 0 on success and -EBUSY if any part of range cannot be isolated.
+ *
+ * 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.
+ */
+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(!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 &&
+ set_migratetype_isolate(page, migratetype, skip_hwpoisoned_pages)) {
+ 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.
+ */
+int 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);
+ }
+ 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 the last tested pfn.
+ */
+static unsigned long
+__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 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 << page_order(page);
+ else if (skip_hwpoisoned_pages && PageHWPoison(page))
+ /* A HWPoisoned page cannot be also PageBuddy */
+ 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,
+ bool skip_hwpoisoned_pages)
+{
+ 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,
+ skip_hwpoisoned_pages);
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ trace_test_pages_isolated(start_pfn, end_pfn, pfn);
+
+ return pfn < end_pfn ? -EBUSY : 0;
+}
+
+struct page *alloc_migrate_target(struct page *page, unsigned long private)
+{
+ return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]);
+}