1 files changed, 19 insertions, 2 deletions

diff --git a/drivers/acpi/acpica/exmutex.c b/drivers/acpi/acpica/exmutex.c
index d7cb030a21f8..77a592aa53c0 100644
--- a/drivers/acpi/acpica/exmutex.c
+++ b/drivers/acpi/acpica/exmutex.c
@@ -83,6 +83,15 @@ void acpi_ex_unlink_mutex(union acpi_operand_object *obj_desc)
 
         if (obj_desc->mutex.prev) {
                 (obj_desc->mutex.prev)->mutex.next = obj_desc->mutex.next;
+
+                /*
+                 * Migrate the previous sync level associated with this mutex to the
+                 * previous mutex on the list so that it may be preserved. This handles
+                 * the case where several mutexes have been acquired at the same level,
+                 * but are not released in opposite order.
+                 */
+                (obj_desc->mutex.prev)->mutex.original_sync_level =
+                    obj_desc->mutex.original_sync_level;
         } else {
                 thread->acquired_mutex_list = obj_desc->mutex.next;
         }
@@ -349,6 +358,7 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
                       struct acpi_walk_state *walk_state)
 {
         acpi_status status = AE_OK;
+        u8 previous_sync_level;
 
         ACPI_FUNCTION_TRACE(ex_release_mutex);
 
@@ -404,14 +414,21 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
                 return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
         }
 
+        /*
+         * Get the previous sync_level from the head of the acquired mutex list.
+         * This handles the case where several mutexes at the same level have been
+         * acquired, but are not released in reverse order.
+         */
+        previous_sync_level =
+            walk_state->thread->acquired_mutex_list->mutex.original_sync_level;
+
         status = acpi_ex_release_mutex_object(obj_desc);
 
         if (obj_desc->mutex.acquisition_depth == 0) {
 
                 /* Restore the original sync_level */
 
-                walk_state->thread->current_sync_level =
-                    obj_desc->mutex.original_sync_level;
+                walk_state->thread->current_sync_level = previous_sync_level;
         }
         return_ACPI_STATUS(status);
 }