[PATCH 2/2] zsmalloc: move migration destination zspage inuse check

From: Sergey Senozhatsky
Date: Fri Jun 23 2023 - 00:40:47 EST


Destination zspage fullness check need to be done after
zs_object_copy() because that's where source and destination
zspages fullness change. Checking destination zspage fullness
before zs_object_copy() may cause migration to loop through
source zspage sub-pages scanning for allocate objects just to
find out at the end that the destination zspage is full.

Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
mm/zsmalloc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 5d60eaedc3b7..4a84f7877669 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1620,10 +1620,6 @@ static void migrate_zspage(struct zs_pool *pool, struct size_class *class,
continue;
}

- /* Stop if there is no more space */
- if (zspage_full(class, get_zspage(d_page)))
- break;
-
used_obj = handle_to_obj(handle);
free_obj = obj_malloc(pool, get_zspage(d_page), handle);
zs_object_copy(class, free_obj, used_obj);
@@ -1631,6 +1627,10 @@ static void migrate_zspage(struct zs_pool *pool, struct size_class *class,
record_obj(handle, free_obj);
obj_free(class->size, used_obj);

+ /* Stop if there is no more space */
+ if (zspage_full(class, get_zspage(d_page)))
+ break;
+
/* Stop if there are no more objects to migrate */
if (zspage_empty(get_zspage(s_page)))
break;
--
2.41.0.162.gfafddb0af9-goog