From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH v3] memcg: refactor mem_cgroup_resize_limit() Date: Tue, 13 Jun 2017 13:35:45 +0200 Message-ID: <20170613113545.GH10819@dhcp22.suse.cz> References: <20170601230212.30578-1-yuzhao@google.com> <20170604211807.32685-1-yuzhao@google.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20170604211807.32685-1-yuzhao-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Yu Zhao Cc: Johannes Weiner , Vladimir Davydov , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, n.borisov.lkml-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org [Sorry for a late reponse] On Sun 04-06-17 14:18:07, Yu Zhao wrote: > mem_cgroup_resize_limit() and mem_cgroup_resize_memsw_limit() have > identical logics. Refactor code so we don't need to keep two pieces > of code that does same thing. > > Signed-off-by: Yu Zhao > Acked-by: Vladimir Davydov It is nice to see removal of the code duplication. I have one comment though [...] > @@ -2498,22 +2449,24 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg, > } > > mutex_lock(&memcg_limit_mutex); > - if (limit < memcg->memory.limit) { > + inverted = memsw ? limit < memcg->memory.limit : > + limit > memcg->memsw.limit; > + if (inverted) { > mutex_unlock(&memcg_limit_mutex); > ret = -EINVAL; > break; > } This is just too ugly and hard to understand. inverted just doesn't give you a good clue what is going on. What do you think about something like /* * Make sure that the new limit (memsw or hard limit) doesn't * break our basic invariant that memory.limit <= memsw.limit */ limits_invariant = memsw ? limit >= memcg->memory.limit : limit <= mmecg->memsw.limit; if (!limits_invariant) { mutex_unlock(&memcg_limit_mutex); ret = -EINVAL; break; } with that feel free to add Acked-by: Michal Hocko -- Michal Hocko SUSE Labs