Commit fd4fd0a8 authored by Michal Koutný's avatar Michal Koutný Committed by Tejun Heo
Browse files

mm: Add transformation message for per-memcg swappiness 

The concept of per-memcg swappiness has never landed well in memcg for
cgroup v2. Add a message to users who use it on v1 hierarchy.
Decreased swappiness transforms to memory.swap.max=0 whereas
increased swappiness transforms into active memory.reclaim operation.

Link: https://lore.kernel.org/r/1577252208-32419-1-git-send-email-teawater@gmail.com/


Signed-off-by: default avatarMichal Koutný <mkoutny@suse.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 103149a0

Documentation/admin-guide/cgroup-v1/memory.rst

+1 −0
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ Brief summary of control files. 
                                     used.

 memory.swappiness		     set/show swappiness parameter of vmscan

				     (See sysctl's vm.swappiness)

				     Per memcg knob does not exist in cgroup v2.

 memory.move_charge_at_immigrate     This knob is deprecated.

 memory.oom_control		     set/show oom controls.

                                     This knob is deprecated and shouldn't be

mm/memcontrol-v1.c

+4 −2
Original line number Diff line number Diff line
@@ -1855,9 +1855,11 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css, 
	if (val > MAX_SWAPPINESS)

		return -EINVAL;



	if (!mem_cgroup_is_root(memcg))

	if (!mem_cgroup_is_root(memcg)) {

		pr_info_once("Per memcg swappiness does not exist in cgroup v2. "

			     "See memory.reclaim or memory.swap.max there\n ")

		WRITE_ONCE(memcg->swappiness, val);

	else

	} else

		WRITE_ONCE(vm_swappiness, val);



	return 0;