diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
index dff6543bf5..7b5839ccd6 100644
--- a/src/basic/cgroup-util.c
+++ b/src/basic/cgroup-util.c
@@ -342,7 +342,8 @@ int cg_kill(
                 return r;
 
         /* Only in case of killing with SIGKILL and when using cgroupsv2, kill remaining threads manually as
-           a workaround for kernel bug. It was fixed in 5.2-rc5 (c03cd7738a83). */
+           a workaround for kernel bug. It was fixed in 5.2-rc5 (c03cd7738a83), backported to 4.19.66
+           (4340d175b898) and 4.14.138 (feb6b123b7dd). */
         r = cg_unified_controller(controller);
         if (r < 0)
                 return r;