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-rw-r--r--mm/compaction.c32
1 files changed, 25 insertions, 7 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 21bf292b..1c7195d 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1125,27 +1125,26 @@ int sysctl_extfrag_threshold = 500;
* @nodemask: The allowed nodes to allocate from
* @mode: The migration mode for async, sync light, or sync migration
* @contended: Return value that is true if compaction was aborted due to lock contention
- * @page: Optionally capture a free page of the requested order during compaction
+ * @candidate_zone: Return the zone where we think allocation should succeed
*
* This is the main entry point for direct page compaction.
*/
unsigned long try_to_compact_pages(struct zonelist *zonelist,
int order, gfp_t gfp_mask, nodemask_t *nodemask,
- enum migrate_mode mode, bool *contended)
+ enum migrate_mode mode, bool *contended,
+ struct zone **candidate_zone)
{
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
int may_enter_fs = gfp_mask & __GFP_FS;
int may_perform_io = gfp_mask & __GFP_IO;
struct zoneref *z;
struct zone *zone;
- int rc = COMPACT_SKIPPED;
+ int rc = COMPACT_DEFERRED;
int alloc_flags = 0;
/* Check if the GFP flags allow compaction */
if (!order || !may_enter_fs || !may_perform_io)
- return rc;
-
- count_compact_event(COMPACTSTALL);
+ return COMPACT_SKIPPED;
#ifdef CONFIG_CMA
if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
@@ -1156,14 +1155,33 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
nodemask) {
int status;
+ if (compaction_deferred(zone, order))
+ continue;
+
status = compact_zone_order(zone, order, gfp_mask, mode,
contended);
rc = max(status, rc);
/* If a normal allocation would succeed, stop compacting */
if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0,
- alloc_flags))
+ alloc_flags)) {
+ *candidate_zone = zone;
+ /*
+ * We think the allocation will succeed in this zone,
+ * but it is not certain, hence the false. The caller
+ * will repeat this with true if allocation indeed
+ * succeeds in this zone.
+ */
+ compaction_defer_reset(zone, order, false);
break;
+ } else if (mode != MIGRATE_ASYNC) {
+ /*
+ * We think that allocation won't succeed in this zone
+ * so we defer compaction there. If it ends up
+ * succeeding after all, it will be reset.
+ */
+ defer_compaction(zone, order);
+ }
}
return rc;
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