On Wed 02-09-20 08:53:49, Pavel Tatashin wrote: > On Wed, Sep 2, 2020 at 7:32 AM Michal Hocko <mhocko@xxxxxxxx> wrote: > > > > On Wed 02-09-20 11:53:00, Vlastimil Babka wrote: > > > >> > > Thread #2: ccs killer kthread > > > >> > > css_killed_work_fn > > > >> > > cgroup_mutex <- Grab this Mutex > > > >> > > mem_cgroup_css_offline > > > >> > > memcg_offline_kmem.part > > > >> > > memcg_deactivate_kmem_caches > > > >> > > get_online_mems > > > >> > > mem_hotplug_lock <- waits for Thread#1 to get read access > > > > And one more thing. THis has been brought up several times already. > > Maybe I have forgoten but why do we take hotplug locks in this path in > > the first place? Memory hotplug notifier takes slab_mutex so this > > shouldn't be really needed. > > Good point, it seems this lock can be completely removed from > memcg_deactivate_kmem_caches I am pretty sure we have discussed that in the past. But I do not remember the outcome. Either we have concluded that this is indeed the case but nobody came up with a patch or we have hit some obscure issue... Maybe David/Roman rememeber more than I do. -- Michal Hocko SUSE Labs
