+ mm-compaction-simplify-should_compact_retry-fix.patch added to mm-unstable branch

+ mm-compaction-simplify-should_compact_retry-fix.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm-compaction-simplify-should_compact_retry-fix
has been added to the -mm mm-unstable branch.  Its filename is
     mm-compaction-simplify-should_compact_retry-fix.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-compaction-simplify-should_compact_retry-fix.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: Johannes Weiner <hannes@cmpxchg.org>
Subject: mm-compaction-simplify-should_compact_retry-fix
Date: Fri, 2 Jun 2023 10:47:05 -0400

Vlastimil points out an unintended change. Previously when hitting
max_retries we'd bump the priority level and restart the loop. Now we
bail out and fail instead. Restore the original behavior.

Link: https://lkml.kernel.org/r/20230602144705.GB161817@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |   24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

--- a/mm/page_alloc.c~mm-compaction-simplify-should_compact_retry-fix
+++ a/mm/page_alloc.c
@@ -3506,6 +3506,15 @@ should_compact_retry(struct alloc_contex
 		return false;
 
 	/*
+	 * Compaction was skipped due to a lack of free order-0
+	 * migration targets. Continue if reclaim can help.
+	 */
+	if (compact_result == COMPACT_SKIPPED) {
+		ret = compaction_zonelist_suitable(ac, order, alloc_flags);
+		goto out;
+	}
+
+	/*
 	 * Compaction managed to coalesce some page blocks, but the
 	 * allocation failed presumably due to a race. Retry some.
 	 */
@@ -3522,17 +3531,10 @@ should_compact_retry(struct alloc_contex
 		if (order > PAGE_ALLOC_COSTLY_ORDER)
 			max_retries /= 4;
 
-		ret = ++(*compaction_retries) <= max_retries;
-		goto out;
-	}
-
-	/*
-	 * Compaction was skipped due to a lack of free order-0
-	 * migration targets. Continue if reclaim can help.
-	 */
-	if (compact_result == COMPACT_SKIPPED) {
-		ret = compaction_zonelist_suitable(ac, order, alloc_flags);
-		goto out;
+		if (++(*compaction_retries) <= max_retries) {
+			ret = true;
+			goto out;
+		}
 	}
 
 	/*
_

Patches currently in -mm which might be from hannes@cmpxchg.org are

mm-compaction-remove-compaction-result-helpers.patch
mm-compaction-simplify-should_compact_retry.patch
mm-compaction-simplify-should_compact_retry-fix.patch
mm-compaction-refactor-__compaction_suitable.patch
mm-compaction-refactor-__compaction_suitable-fix.patch
mm-compaction-remove-unnecessary-is_via_compact_memory-checks.patch
mm-compaction-drop-redundant-watermark-check-in-compaction_zonelist_suitable.patch
mm-compaction-have-compaction_suitable-return-bool.patch
mm-page_isolation-write-proper-kerneldoc.patch
mm-compaction-avoid-gfp_nofs-abba-deadlock.patch