1 files changed, 13 insertions, 1 deletions

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index e7414cec220b..2d7c4c11fc63 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -309,7 +309,12 @@ static void free_handle(struct zs_pool *pool, unsigned long handle)
 
 static void record_obj(unsigned long handle, unsigned long obj)
 {
-        *(unsigned long *)handle = obj;
+        /*
+         * lsb of @obj represents handle lock while other bits
+         * represent object value the handle is pointing so
+         * updating shouldn't do store tearing.
+         */
+        WRITE_ONCE(*(unsigned long *)handle, obj);
 }
 
 /* zpool driver */
@@ -1635,6 +1640,13 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
                 free_obj = obj_malloc(d_page, class, handle);
                 zs_object_copy(free_obj, used_obj, class);
                 index++;
+                /*
+                 * record_obj updates handle's value to free_obj and it will
+                 * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
+                 * breaks synchronization using pin_tag(e,g, zs_free) so
+                 * let's keep the lock bit.
+                 */
+                free_obj |= BIT(HANDLE_PIN_BIT);
                 record_obj(handle, free_obj);
                 unpin_tag(handle);
                 obj_free(pool, class, used_obj);