diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst index 0ae4f564c2d6..6ec63c239616 100644 --- a/Documentation/admin-guide/cgroup-v1/memory.rst +++ b/Documentation/admin-guide/cgroup-v1/memory.rst @@ -82,6 +82,8 @@ Brief summary of control files. memory.swappiness set/show swappiness parameter of vmscan (See sysctl's vm.swappiness) memory.move_charge_at_immigrate set/show controls of moving charges + This knob is deprecated and shouldn't be + used. memory.oom_control set/show oom controls. memory.numa_stat show the number of memory usage per numa node @@ -745,8 +747,15 @@ NOTE2: It is recommended to set the soft limit always below the hard limit, otherwise the hard limit will take precedence. -8. Move charges at task migration -================================= +8. Move charges at task migration (DEPRECATED!) +=============================================== + +THIS IS DEPRECATED! + +It's expensive and unreliable! It's better practice to launch workload +tasks directly from inside their target cgroup. Use dedicated workload +cgroups to allow fine-grained policy adjustments without having to +move physical pages between control domains. Users can move charges associated with a task along with task migration, that is, uncharge task's pages from the old cgroup and charge them to the new cgroup. diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 62861daf3589..16beae167d8c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3775,6 +3775,10 @@ static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css, { struct mem_cgroup *memcg = mem_cgroup_from_css(css); + pr_warn_once("Cgroup memory moving (move_charge_at_immigrate) is deprecated. " + "Please report your usecase to linux-mm@kvack.org if you " + "depend on this functionality.\n"); + if (val & ~MOVE_MASK) return -EINVAL;