2021-04-07 22:02:07

by Mel Gorman

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

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 <[email protected]>
---
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