The patch titled
Subject: mm: compaction: only force pageblock scan completion when skip hints are obeyed
has been added to the -mm mm-unstable branch. Its filename is
mm-compaction-only-force-pageblock-scan-completion-when-skip-hints-are-obeyed.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-compaction-only-force-pageblock-scan-completion-when-skip-hints-are-obeyed.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm: compaction: only force pageblock scan completion when skip hints are obeyed
Date: Mon, 15 May 2023 12:33:42 +0100
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@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx>
Cc: Jiri Slaby <jirislaby@xxxxxxxxxx>
Cc: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Pedro Falcato <pedro.falcato@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/mm/compaction.c~mm-compaction-only-force-pageblock-scan-completion-when-skip-hints-are-obeyed
+++ a/mm/compaction.c
@@ -2485,7 +2485,8 @@ 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
@@ -2494,7 +2495,7 @@ 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;
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
mm-compaction-ensure-rescanning-only-happens-on-partially-scanned-pageblocks.patch
mm-compaction-only-force-pageblock-scan-completion-when-skip-hints-are-obeyed.patch
mm-compaction-update-pageblock-skip-when-first-migration-candidate-is-not-at-the-start.patch
revert-revert-mm-compaction-fix-set-skip-in-fast_find_migrateblock.patch
