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authorMatthew Wilcox <willy@infradead.org>2023-07-27 21:39:44 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-08-21 13:37:30 -0700
commit866ff80176aa1f9c0ba65f2164cf608c5cde4851 (patch)
treee574ac80ff0b938a30c16576a86bf30ad671a4e5 /mm/compaction.c
parent108c3dc6cd3dbe36824469b7ea860337978e0439 (diff)
mm: improve the comment in isolate_migratepages_block()
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. Link: https://lkml.kernel.org/r/ZMLWEB4m3zvX6SBN@casper.infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/compaction.c')
-rw-r--r--mm/compaction.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index e6ac0ef4c178..c4d3a3129fd5 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1100,13 +1100,13 @@ 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;