The patch titled
Subject: mm-compaction-more-focused-lru-and-pcplists-draining-fix
has been added to the -mm tree. Its filename is
mm-compaction-more-focused-lru-and-pcplists-draining-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-more-focused-lru-and-pcplists-draining-fix.patch
echo and later at
echo http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-more-focused-lru-and-pcplists-draining-fix.patch
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From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm-compaction-more-focused-lru-and-pcplists-draining-fix
As Joonsoo Kim pointed out, last_migrate_pfn was reset to 0 by mistake at
each iteration in compact_zone(). This mistake could result in fail to
recognize immediately draining points for orders smaller than pageblock.
Joonsoo has also suggested an improvement to detecting cc->order aligned
block where migration might have occured - before this fix, some of the
drain opportunities might have been missed.
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
diff -puN mm/compaction.c~mm-compaction-more-focused-lru-and-pcplists-draining-fix mm/compaction.c
--- a/mm/compaction.c~mm-compaction-more-focused-lru-and-pcplists-draining-fix
+++ a/mm/compaction.c
@@ -1158,6 +1158,7 @@ static int compact_zone(struct zone *zon
unsigned long end_pfn = zone_end_pfn(zone);
const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
const bool sync = cc->mode != MIGRATE_ASYNC;
+ unsigned long last_migrated_pfn = 0;
ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
cc->classzone_idx);
@@ -1203,7 +1204,7 @@ static int compact_zone(struct zone *zon
while ((ret = compact_finished(zone, cc, migratetype)) ==
COMPACT_CONTINUE) {
int err;
- unsigned long last_migrated_pfn = 0;
+ unsigned long isolate_start_pfn = cc->migrate_pfn;
switch (isolate_migratepages(zone, cc)) {
case ISOLATE_ABORT:
@@ -1244,21 +1245,22 @@ static int compact_zone(struct zone *zon
}
/*
- * Record where we have freed pages by migration and not yet
- * flushed them to buddy allocator. Subtract 1, because often
- * we finish a pageblock and migrate_pfn points to the first
- * page* of the next one. In that case we want the drain below
- * to happen immediately.
+ * Record where we could have freed pages by migration and not
+ * yet flushed them to buddy allocator. We use the pfn that
+ * isolate_migratepages() started from in this loop iteration
+ * - this is the lowest page that could have been isolated and
+ * then freed by migration.
*/
if (!last_migrated_pfn)
- last_migrated_pfn = cc->migrate_pfn - 1;
+ last_migrated_pfn = isolate_start_pfn;
check_drain:
/*
- * Have we moved away from the previous cc->order aligned block
- * where we migrated from? If yes, flush the pages that were
- * freed, so that they can merge and compact_finished() can
- * detect immediately if allocation should succeed.
+ * Has the migration scanner moved away from the previous
+ * cc->order aligned block where we migrated from? If yes,
+ * flush the pages that were freed, so that they can merge and
+ * compact_finished() can detect immediately if allocation
+ * would succeed.
*/
if (cc->order > 0 && last_migrated_pfn) {
int cpu;
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-introduce-single-zone-pcplists-drain.patch
mm-page_isolation-drain-single-zone-pcplists.patch
mm-cma-drain-single-zone-pcplists.patch
mm-memory_hotplug-failure-drain-single-zone-pcplists.patch
mm-compaction-pass-classzone_idx-and-alloc_flags-to-watermark-checking.patch
mm-compaction-pass-classzone_idx-and-alloc_flags-to-watermark-checking-fix.patch
mm-compaction-simplify-deferred-compaction.patch
mm-compaction-simplify-deferred-compaction-fix.patch
mm-compaction-defer-only-on-compact_complete.patch
mm-compaction-always-update-cached-scanner-positions.patch
mm-compaction-always-update-cached-scanner-positions-fix.patch
mm-compaction-always-update-cached-scanner-positions-fix-checkpatch-fixes.patch
mm-compaction-more-focused-lru-and-pcplists-draining.patch
mm-compaction-more-focused-lru-and-pcplists-draining-fix.patch
mm-debug-pagealloc-cleanup-page-guard-code.patch
mm-page_alloc-store-updated-page-migratetype-to-avoid-misusing-stale-value.patch
mm-page_alloc-store-updated-page-migratetype-to-avoid-misusing-stale-value-fix.patch
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