[PATCH v5 1/6] mm: page_isolation: move has_unmovable_pages() to mm/page_isolation.c

Zi Yan
2022-02-11T16:51:14Z

has_unmovable_pages() is only used in mm/page_isolation.c. Move it from
mm/page_alloc.c and make it static.

Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
include/linux/page-isolation.h | 2 -
mm/page_alloc.c | 119 ---------------------------------
mm/page_isolation.c | 119 +++++++++++++++++++++++++++++++++
3 files changed, 119 insertions(+), 121 deletions(-)

diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index 572458016331..e14eddf6741a 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -33,8 +33,6 @@ static inline bool is_migrate_isolate(int migratetype)
#define MEMORY_OFFLINE 0x1
#define REPORT_FAILURE 0x2

-struct page *has_unmovable_pages(struct zone *zone, struct page *page,
- int migratetype, int flags);
void set_pageblock_migratetype(struct page *page, int migratetype);
int move_freepages_block(struct zone *zone, struct page *page,
int migratetype, int *num_movable);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cface1d38093..e2c6a67fc386 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8962,125 +8962,6 @@ void *__init alloc_large_system_hash(const char *tablename,
return table;
}

-/*
- * This function checks whether pageblock includes unmovable pages or not.
- *
- * PageLRU check without isolation or lru_lock could race so that
- * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
- * check without lock_page also may miss some movable non-lru pages at
- * race condition. So you can't expect this function should be exact.
- *
- * Returns a page without holding a reference. If the caller wants to
- * dereference that page (e.g., dumping), it has to make sure that it
- * cannot get removed (e.g., via memory unplug) concurrently.
- *
- */
-struct page *has_unmovable_pages(struct zone *zone, struct page *page,
- int migratetype, int flags)
-{
- unsigned long iter = 0;
- unsigned long pfn = page_to_pfn(page);
- unsigned long offset = pfn % pageblock_nr_pages;
-
- if (is_migrate_cma_page(page)) {
- /*
- * CMA allocations (alloc_contig_range) really need to mark
- * isolate CMA pageblocks even when they are not movable in fact
- * so consider them movable here.
- */
- if (is_migrate_cma(migratetype))
- return NULL;
-
- return page;
- }
-
- for (; iter < pageblock_nr_pages - offset; iter++) {
- page = pfn_to_page(pfn + iter);
-
- /*
- * Both, bootmem allocations and memory holes are marked
- * PG_reserved and are unmovable. We can even have unmovable
- * allocations inside ZONE_MOVABLE, for example when
- * specifying "movablecore".
- */
- if (PageReserved(page))
- return page;
-
- /*
- * If the zone is movable and we have ruled out all reserved
- * pages then it should be reasonably safe to assume the rest
- * is movable.
- */
- if (zone_idx(zone) == ZONE_MOVABLE)
- continue;
-
- /*
- * Hugepages are not in LRU lists, but they're movable.
- * THPs are on the LRU, but need to be counted as #small pages.
- * We need not scan over tail pages because we don't
- * handle each tail page individually in migration.
- */
- if (PageHuge(page) || PageTransCompound(page)) {
- struct page *head = compound_head(page);
- unsigned int skip_pages;
-
- if (PageHuge(page)) {
- if (!hugepage_migration_supported(page_hstate(head)))
- return page;
- } else if (!PageLRU(head) && !__PageMovable(head)) {
- return page;
- }
-
- skip_pages = compound_nr(head) - (page - head);
- iter += skip_pages - 1;
- continue;
- }
-
- /*
- * We can't use page_count without pin a page
- * because another CPU can free compound page.
- * This check already skips compound tails of THP
- * because their page->_refcount is zero at all time.
- */
- if (!page_ref_count(page)) {
- if (PageBuddy(page))
- iter += (1 << buddy_order(page)) - 1;
- continue;
- }
-
- /*
- * The HWPoisoned page may be not in buddy system, and
- * page_count() is not 0.
- */
- if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
- continue;
-
- /*
- * We treat all PageOffline() pages as movable when offlining
- * to give drivers a chance to decrement their reference count
- * in MEM_GOING_OFFLINE in order to indicate that these pages
- * can be offlined as there are no direct references anymore.
- * For actually unmovable PageOffline() where the driver does
- * not support this, we will fail later when trying to actually
- * move these pages that still have a reference count > 0.
- * (false negatives in this function only)
- */
- if ((flags & MEMORY_OFFLINE) && PageOffline(page))
- continue;
-
- if (__PageMovable(page) || PageLRU(page))
- continue;
-
- /*
- * If there are RECLAIMABLE pages, we need to check
- * it. But now, memory offline itself doesn't call
- * shrink_node_slabs() and it still to be fixed.
- */
- return page;
- }
- return NULL;
-}
-
#ifdef CONFIG_CONTIG_ALLOC
static unsigned long pfn_max_align_down(unsigned long pfn)
{
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index f67c4c70f17f..b34f1310aeaa 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -15,6 +15,125 @@
#define CREATE_TRACE_POINTS
#include <trace/events/page_isolation.h>

+/*
+ * This function checks whether pageblock includes unmovable pages or not.
+ *
+ * PageLRU check without isolation or lru_lock could race so that
+ * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
+ * check without lock_page also may miss some movable non-lru pages at
+ * race condition. So you can't expect this function should be exact.
+ *
+ * Returns a page without holding a reference. If the caller wants to
+ * dereference that page (e.g., dumping), it has to make sure that it
+ * cannot get removed (e.g., via memory unplug) concurrently.
+ *
+ */
+static struct page *has_unmovable_pages(struct zone *zone, struct page *page,
+ int migratetype, int flags)
+{
+ unsigned long iter = 0;
+ unsigned long pfn = page_to_pfn(page);
+ unsigned long offset = pfn % pageblock_nr_pages;
+
+ if (is_migrate_cma_page(page)) {
+ /*
+ * CMA allocations (alloc_contig_range) really need to mark
+ * isolate CMA pageblocks even when they are not movable in fact
+ * so consider them movable here.
+ */
+ if (is_migrate_cma(migratetype))
+ return NULL;
+
+ return page;
+ }
+
+ for (; iter < pageblock_nr_pages - offset; iter++) {
+ page = pfn_to_page(pfn + iter);
+
+ /*
+ * Both, bootmem allocations and memory holes are marked
+ * PG_reserved and are unmovable. We can even have unmovable
+ * allocations inside ZONE_MOVABLE, for example when
+ * specifying "movablecore".
+ */
+ if (PageReserved(page))
+ return page;
+
+ /*
+ * If the zone is movable and we have ruled out all reserved
+ * pages then it should be reasonably safe to assume the rest
+ * is movable.
+ */
+ if (zone_idx(zone) == ZONE_MOVABLE)
+ continue;
+
+ /*
+ * Hugepages are not in LRU lists, but they're movable.
+ * THPs are on the LRU, but need to be counted as #small pages.
+ * We need not scan over tail pages because we don't
+ * handle each tail page individually in migration.
+ */
+ if (PageHuge(page) || PageTransCompound(page)) {
+ struct page *head = compound_head(page);
+ unsigned int skip_pages;
+
+ if (PageHuge(page)) {
+ if (!hugepage_migration_supported(page_hstate(head)))
+ return page;
+ } else if (!PageLRU(head) && !__PageMovable(head)) {
+ return page;
+ }
+
+ skip_pages = compound_nr(head) - (page - head);
+ iter += skip_pages - 1;
+ continue;
+ }
+
+ /*
+ * We can't use page_count without pin a page
+ * because another CPU can free compound page.
+ * This check already skips compound tails of THP
+ * because their page->_refcount is zero at all time.
+ */
+ if (!page_ref_count(page)) {
+ if (PageBuddy(page))
+ iter += (1 << buddy_order(page)) - 1;
+ continue;
+ }
+
+ /*
+ * The HWPoisoned page may be not in buddy system, and
+ * page_count() is not 0.
+ */
+ if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
+ continue;
+
+ /*
+ * We treat all PageOffline() pages as movable when offlining
+ * to give drivers a chance to decrement their reference count
+ * in MEM_GOING_OFFLINE in order to indicate that these pages
+ * can be offlined as there are no direct references anymore.
+ * For actually unmovable PageOffline() where the driver does
+ * not support this, we will fail later when trying to actually
+ * move these pages that still have a reference count > 0.
+ * (false negatives in this function only)
+ */
+ if ((flags & MEMORY_OFFLINE) && PageOffline(page))
+ continue;
+
+ if (__PageMovable(page) || PageLRU(page))
+ continue;
+
+ /*
+ * If there are RECLAIMABLE pages, we need to check
+ * it. But now, memory offline itself doesn't call
+ * shrink_node_slabs() and it still to be fixed.
+ */
+ return page;
+ }
+ return NULL;
+}
+
static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
{
struct zone *zone = page_zone(page);
--
2.34.1