From: Mel Gorman <mgorman@techsingularity.net>
Date: Mon, 15 May 2023 11:33:42 +0000 (+0100)
Subject: mm: compaction: only force pageblock scan completion when skip hints are obeyed
X-Git-Tag: v6.5-rc1~176^2~346
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9ecc5fc50a9c75b0af252913163a9f1ac4206b17;p=thirdparty%2Flinux.git

mm: compaction: only force pageblock scan completion when skip hints are obeyed

fast_find_migrateblock relies on skip hints to avoid rescanning a recently
selected pageblock but compact_zone() only forces the pageblock scan
completion to set the skip hint if in direct compaction.  While this
prevents direct compaction repeatedly scanning a subset of blocks due to
fast_find_migrateblock(), it does not prevent proactive compaction, node
compaction and kcompactd encountering the same problem described in commit
cfccd2e63e7e ("mm, compaction: finish pageblocks on complete migration
failure").

Force the scan completion of a pageblock to set the skip hint if skip
hints are obeyed to prevent fast_find_migrateblock() repeatedly selecting
a subset of pageblocks.

Link: https://lkml.kernel.org/r/20230515113344.6869-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Raghavendra K T <raghavendra.kt@amd.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Chuyi Zhou <zhouchuyi@bytedance.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/compaction.c b/mm/compaction.c
index d16b0fcd6db5a..009128d1e4efe 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2457,7 +2457,8 @@ rescan:
 			}
 			/*
 			 * If an ASYNC or SYNC_LIGHT fails to migrate a page
-			 * within the current order-aligned block, scan the
+			 * within the current order-aligned block and
+			 * fast_find_migrateblock may be used then scan the
 			 * remainder of the pageblock. This will mark the
 			 * pageblock "skip" to avoid rescanning in the near
 			 * future. This will isolate more pages than necessary
@@ -2466,7 +2467,7 @@ rescan:
 			 * recently partially scanned.
 			 */
 			if (!pageblock_aligned(cc->migrate_pfn) &&
-			    cc->direct_compaction && !cc->finish_pageblock &&
+			    !cc->ignore_skip_hint && !cc->finish_pageblock &&
 			    (cc->mode < MIGRATE_SYNC)) {
 				cc->finish_pageblock = true;