[PATCH 08/11] mm/page_alloc: Remove duplicate checks if migratetype should be isolated

[Mel Gorman]

Both free_pcppages_bulk() and free_one_page() have very similar
checks about whether a pages migratetype has changed under the
zone lock. Use a common helper.

Signed-off-by: Mel Gorman <mgor...@techsingularity.net>
---
 mm/page_alloc.c | 32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bd75102ef1e1..1bb5b522a0f9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1354,6 +1354,23 @@ static inline void prefetch_buddy(struct page *page)
        prefetch(buddy);
 }
 
+/*
+ * The migratetype of a page may have changed due to isolation so check.
+ * Assumes the caller holds the zone->lock to serialise against page
+ * isolation.
+ */
+static inline int
+check_migratetype_isolated(struct zone *zone, struct page *page, unsigned long 
pfn, int migratetype)
+{
+       /* If isolating, check if the migratetype has changed */
+       if (unlikely(has_isolate_pageblock(zone) ||
+               is_migrate_isolate(migratetype))) {
+               migratetype = get_pfnblock_migratetype(page, pfn);
+       }
+
+       return migratetype;
+}
+
 /*
  * Frees a number of pages from the PCP lists
  * Assumes all pages on list are in same zone, and of same order.
@@ -1371,7 +1388,6 @@ static void free_pcppages_bulk(struct zone *zone, int 
count,
        int migratetype = 0;
        int batch_free = 0;
        int prefetch_nr = READ_ONCE(pcp->batch);
-       bool isolated_pageblocks;
        struct page *page, *tmp;
        LIST_HEAD(head);
 
@@ -1433,21 +1449,20 @@ static void free_pcppages_bulk(struct zone *zone, int 
count,
         * both PREEMPT_RT and non-PREEMPT_RT configurations.
         */
        spin_lock(&zone->lock);
-       isolated_pageblocks = has_isolate_pageblock(zone);
 
        /*
         * Use safe version since after __free_one_page(),
         * page->lru.next will not point to original list.
         */
        list_for_each_entry_safe(page, tmp, &head, lru) {
+               unsigned long pfn = page_to_pfn(page);
                int mt = get_pcppage_migratetype(page);
+
                /* MIGRATE_ISOLATE page should not go to pcplists */
                VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
-               /* Pageblock could have been isolated meanwhile */
-               if (unlikely(isolated_pageblocks))
-                       mt = get_pageblock_migratetype(page);
 
-               __free_one_page(page, page_to_pfn(page), zone, 0, mt, FPI_NONE);
+               mt = check_migratetype_isolated(zone, page, pfn, mt);
+               __free_one_page(page, pfn, zone, 0, mt, FPI_NONE);
                trace_mm_page_pcpu_drain(page, 0, mt);
        }
        spin_unlock(&zone->lock);
@@ -1459,10 +1474,7 @@ static void free_one_page(struct zone *zone,
                                int migratetype, fpi_t fpi_flags)
 {
        spin_lock(&zone->lock);
-       if (unlikely(has_isolate_pageblock(zone) ||
-               is_migrate_isolate(migratetype))) {
-               migratetype = get_pfnblock_migratetype(page, pfn);
-       }
+       migratetype = check_migratetype_isolated(zone, page, pfn, migratetype);
        __free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
        spin_unlock(&zone->lock);
 }
-- 
2.26.2