zsmalloc: move migration destination zspage inuse check

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.

Link: https://lkml.kernel.org/r/20230624053120.643409-3-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Alexey Romanov <avromanov@sberdevices.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 5d60eae..4a84f78 100644 (file)
--- 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;