mm, compaction: distinguish between full and partial COMPACT_COMPLETE
COMPACT_COMPLETE now means that compaction and free scanner met. This
is not very useful information if somebody just wants to use this
feedback and make any decisions based on that. The current caller might
be a poor guy who just happened to scan tiny portion of the zone and
that could be the reason no suitable pages were compacted. Make sure we
distinguish the full and partial zone walks.
Consumers should treat COMPACT_PARTIAL_SKIPPED as a potential success
and be optimistic in retrying.
The existing users of COMPACT_COMPLETE are conservatively changed to use
COMPACT_PARTIAL_SKIPPED as well but some of them should be probably
reconsidered and only defer the compaction only for COMPACT_COMPLETE
with the new semantic.
This patch shouldn't introduce any functional changes.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/compaction.c b/mm/compaction.c
index b2b9447..4af1577 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1252,7 +1252,10 @@
if (cc->direct_compaction)
zone->compact_blockskip_flush = true;
- return COMPACT_COMPLETE;
+ if (cc->whole_zone)
+ return COMPACT_COMPLETE;
+ else
+ return COMPACT_PARTIAL_SKIPPED;
}
if (is_via_compact_memory(cc->order))
@@ -1413,6 +1416,10 @@
zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
}
+
+ if (cc->migrate_pfn == start_pfn)
+ cc->whole_zone = true;
+
cc->last_migrated_pfn = 0;
trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
@@ -1634,7 +1641,8 @@
goto break_loop;
}
- if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) {
+ if (mode != MIGRATE_ASYNC && (status == COMPACT_COMPLETE ||
+ status == COMPACT_PARTIAL_SKIPPED)) {
/*
* We think that allocation won't succeed in this zone
* so we defer compaction there. If it ends up
@@ -1881,7 +1889,7 @@
cc.classzone_idx, 0)) {
success = true;
compaction_defer_reset(zone, cc.order, false);
- } else if (status == COMPACT_COMPLETE) {
+ } else if (status == COMPACT_PARTIAL_SKIPPED || status == COMPACT_COMPLETE) {
/*
* We use sync migration mode here, so we defer like
* sync direct compaction does.