The patch titled
Subject: mm: page_alloc: avoid merging non-fallbackable pageblocks with others
has been added to the -mm tree. Its filename is
mm-page_alloc-avoid-merging-non-fallbackable-pageblocks-with-others.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-avoid-merging-non-fallbackable-pageblocks-with-others.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-avoid-merging-non-fallbackable-pageblocks-with-others.patch
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------------------------------------------------------
From: Zi Yan <ziy@xxxxxxxxxx>
Subject: mm: page_alloc: avoid merging non-fallbackable pageblocks with others
This is done in addition to MIGRATE_ISOLATE pageblock merge avoidance. It
prepares for the upcoming removal of the MAX_ORDER-1 alignment requirement
for CMA and alloc_contig_range().
MIGRATE_HIGHATOMIC should not merge with other migratetypes like
MIGRATE_ISOLATE and MIGRARTE_CMA[1], so this commit prevents that too.
Remove MIGRATE_CMA and MIGRATE_ISOLATE from fallbacks list, since they
are never used.
[1] https://lore.kernel.org/linux-mm/20211130100853.GP3366@xxxxxxxxxxxxxxxxxxx/
Link: https://lkml.kernel.org/r/20220124175957.1261961-1-zi.yan@xxxxxxxx
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 11 +++++++++
mm/page_alloc.c | 46 ++++++++++++++++++---------------------
2 files changed, 33 insertions(+), 24 deletions(-)
--- a/include/linux/mmzone.h~mm-page_alloc-avoid-merging-non-fallbackable-pageblocks-with-others
+++ a/include/linux/mmzone.h
@@ -83,6 +83,17 @@ static inline bool is_migrate_movable(in
return is_migrate_cma(mt) || mt == MIGRATE_MOVABLE;
}
+/*
+ * Check whether a migratetype can be merged with another migratetype.
+ *
+ * It is only mergeable when it can fall back to other migratetypes for
+ * allocation. See fallbacks[MIGRATE_TYPES][3] in page_alloc.c.
+ */
+static inline bool migratetype_is_mergeable(int mt)
+{
+ return mt < MIGRATE_PCPTYPES;
+}
+
#define for_each_migratetype_order(order, type) \
for (order = 0; order < MAX_ORDER; order++) \
for (type = 0; type < MIGRATE_TYPES; type++)
--- a/mm/page_alloc.c~mm-page_alloc-avoid-merging-non-fallbackable-pageblocks-with-others
+++ a/mm/page_alloc.c
@@ -1099,25 +1099,24 @@ continue_merging:
}
if (order < MAX_ORDER - 1) {
/* If we are here, it means order is >= pageblock_order.
- * We want to prevent merge between freepages on isolate
- * pageblock and normal pageblock. Without this, pageblock
- * isolation could cause incorrect freepage or CMA accounting.
+ * We want to prevent merge between freepages on pageblock
+ * without fallbacks and normal pageblock. Without this,
+ * pageblock isolation could cause incorrect freepage or CMA
+ * accounting or HIGHATOMIC accounting.
*
* We don't want to hit this code for the more frequent
* low-order merging.
*/
- if (unlikely(has_isolate_pageblock(zone))) {
- int buddy_mt;
+ int buddy_mt;
- buddy_pfn = __find_buddy_pfn(pfn, order);
- buddy = page + (buddy_pfn - pfn);
- buddy_mt = get_pageblock_migratetype(buddy);
-
- if (migratetype != buddy_mt
- && (is_migrate_isolate(migratetype) ||
- is_migrate_isolate(buddy_mt)))
- goto done_merging;
- }
+ buddy_pfn = __find_buddy_pfn(pfn, order);
+ buddy = page + (buddy_pfn - pfn);
+ buddy_mt = get_pageblock_migratetype(buddy);
+
+ if (migratetype != buddy_mt
+ && (!migratetype_is_mergeable(migratetype) ||
+ !migratetype_is_mergeable(buddy_mt)))
+ goto done_merging;
max_order = order + 1;
goto continue_merging;
}
@@ -2535,17 +2534,13 @@ struct page *__rmqueue_smallest(struct z
/*
* This array describes the order lists are fallen back to when
* the free lists for the desirable migrate type are depleted
+ *
+ * The other migratetypes do not have fallbacks.
*/
static int fallbacks[MIGRATE_TYPES][3] = {
[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
[MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_TYPES },
-#ifdef CONFIG_CMA
- [MIGRATE_CMA] = { MIGRATE_TYPES }, /* Never used */
-#endif
-#ifdef CONFIG_MEMORY_ISOLATION
- [MIGRATE_ISOLATE] = { MIGRATE_TYPES }, /* Never used */
-#endif
};
#ifdef CONFIG_CMA
@@ -2851,8 +2846,8 @@ static void reserve_highatomic_pageblock
/* Yoink! */
mt = get_pageblock_migratetype(page);
- if (!is_migrate_highatomic(mt) && !is_migrate_isolate(mt)
- && !is_migrate_cma(mt)) {
+ /* Only reserve normal pageblocks (i.e., they can merge with others) */
+ if (migratetype_is_mergeable(mt)) {
zone->nr_reserved_highatomic += pageblock_nr_pages;
set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL);
@@ -3601,8 +3596,11 @@ int __isolate_free_page(struct page *pag
struct page *endpage = page + (1 << order) - 1;
for (; page < endpage; page += pageblock_nr_pages) {
int mt = get_pageblock_migratetype(page);
- if (!is_migrate_isolate(mt) && !is_migrate_cma(mt)
- && !is_migrate_highatomic(mt))
+ /*
+ * Only change normal pageblocks (i.e., they can merge
+ * with others)
+ */
+ if (migratetype_is_mergeable(mt))
set_pageblock_migratetype(page,
MIGRATE_MOVABLE);
}
_
Patches currently in -mm which might be from ziy@xxxxxxxxxx are
mm-page_alloc-avoid-merging-non-fallbackable-pageblocks-with-others.patch
