On 27.07.23 22:39, Matthew Wilcox wrote:
A recent patch shows that not everybody understands that "stabilise the
mapping" really means "prevent the mapping from being freed", so change
the wording to hopefully make that more clear.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
diff --git a/mm/compaction.c b/mm/compaction.c
index 9641e2131901..9be2c3504ff2 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1095,13 +1095,13 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
bool migrate_dirty;
/*
- * Only pages without mappings or that have a
- * ->migrate_folio callback are possible to migrate
- * without blocking. However, we can be racing with
- * truncation so it's necessary to lock the page
- * to stabilise the mapping as truncation holds
- * the page lock until after the page is removed
- * from the page cache.
+ * Only folios without mappings or that have
+ * a ->migrate_folio callback are possible to
+ * migrate without blocking. However, we may
+ * be racing with truncation, which can free
+ * the mapping. Truncation holds the folio lock
+ * until after the folio is removed from the page
+ * cache so holding it ourselves is sufficient.
*/
if (!folio_trylock(folio))
goto isolate_fail_put;
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
--
Cheers,
David / dhildenb
