On Wed 02-09-20 08:53:49, Pavel Tatashin wrote:
On Wed, Sep 2, 2020 at 7:32 AM Michal Hocko mhocko@suse.com 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.