On Thu, Jul 02, 2020 at 11:09:26AM -0700, Roman Gushchin wrote: > Historically the kernel memory accounting was an opt-in feature, which > could be enabled for individual cgroups. But now it's not true, and > it's on by default both on cgroup v1 and cgroup v2. And as long as a > user has at least one non-root memory cgroup, the kernel memory > accounting is on. So in most setups it's either always on (if memory > cgroups are in use and kmem accounting is not disabled), either always > off (otherwise). > > memcg_kmem_enabled() is used in many places to guard the kernel memory > accounting code. If memcg_kmem_enabled() can reverse from returning > true to returning false (as now), we can't rely on it on release paths > and have to check if it was on before. > > If we'll make memcg_kmem_enabled() irreversible (always returning true > after returning it for the first time), it'll make the general logic > more simple and robust. It also will allow to guard some checks which > otherwise would stay unguarded. > > Signed-off-by: Roman Gushchin <guro@xxxxxx> > Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> > Tested-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> > Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > Acked-by: Michal Hocko <mhocko@xxxxxxxx> Andrew, can you, please, put this patch before my slab series? Thank you! Roman
