[Devel] [PATCH hci-8.1 2/3] mm/memcontrol: say where the numa_migrate code comes from

[Konstantin Khorenko]

The comment in the isolation loop tells the rebase history of the code
instead of naming the upstream functions it copies, which is what a
rebase has to compare against. Replace it with those names, name the
original of the allocator too, and drop the leftovers of the copy: the
commented-out conditions and the pre-folio name of the allocator in
the comment to its private argument.

No functional change.

https://virtuozzo.atlassian.net/browse/VSTOR-152197

Feature: mm: interface to migrate memory between NUMA nodes upon userspace request
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 mm/memcontrol.c | 24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a82d5e7bc8694..4c3c06cfcf9fc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3462,7 +3462,7 @@ int ve_enough_memory(long pages)
 #ifdef CONFIG_NUMA
 
 /*
- * memcg_numa_migrate_new_page() private argument. @target_nodes specifies the
+ * memcg_numa_migrate_new_folio() private argument. @target_nodes specifies the
  * set of nodes to allocate pages from. @current_node is the current preferable
  * node, it gets rotated after each allocation.
  */
@@ -3473,7 +3473,8 @@ struct memcg_numa_migrate_struct {
 
 /*
  * Used as an argument for migrate_pages(). Allocated pages are spread evenly
- * among destination nodes.
+ * among destination nodes. The order and gfp choice follow
+ * alloc_migration_target().
  */
 static struct folio *memcg_numa_migrate_new_folio(struct folio *old_folio,
 						  unsigned long private)
@@ -3520,19 +3521,10 @@ static long memcg_numa_isolate_pages(struct lruvec *lruvec,
 		scanned++;
 
 		/*
-		 * Previously here we had a call to
-		 * __isolate_lru_page_prepare(page, ISOLATE_ASYNC_MIGRATE)
-		 * => need to get same parts from __isolate_lru_page_prepare()
-		 * like it's done in isolate_migratepages_block() in commit
-		 * 89f6c88a6ab4 ("mm: __isolate_lru_page_prepare() in
-		 * isolate_migratepages_block()")
-		 *
-		 * The code block below is taken from
-		 * isolate_migratepages_block(), mode variable is defined and
-		 * set to ISOLATE_ASYNC_MIGRATE in order to keep the original
-		 * code unchanged where possible.
-		 *
-		 * Also it is switched to folio, based on isolate_lru_folios().
+		 * The checks below are a copy of the per-folio checks in
+		 * isolate_migratepages_block() with mode == ISOLATE_ASYNC_MIGRATE;
+		 * the isolation itself follows isolate_lru_folios(). Keep both
+		 * in sync with their originals on a rebase.
 		 */
 		folio = lru_to_folio(src);
 
@@ -3552,7 +3544,6 @@ static long memcg_numa_isolate_pages(struct lruvec *lruvec,
 		is_unevictable = folio_test_unevictable(folio);
 
 		/* Compaction might skip unevictable pages but CMA takes them */
-		/* if (is_unevictable) */
 		if (!(mode & ISOLATE_UNEVICTABLE) && is_unevictable)
 			goto isolate_fail;
 
@@ -3567,7 +3558,6 @@ static long memcg_numa_isolate_pages(struct lruvec *lruvec,
 
 		is_dirty = folio_test_dirty(folio);
 
-		/* if (is_dirty) */
 		if (((mode & ISOLATE_ASYNC_MIGRATE) && is_dirty) ||
 		    (mapping && is_unevictable)) {
 			bool migrate_dirty = true;

-- 
2.43.0