--- /dev/null
+/*
+ * 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 "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);
+}
Code Review / kvmfornfv.git / blobdiff