From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH] mm: Make mem_cgroup_id_get_many dependent on MMU and MEMCG_SWAP Date: Thu, 5 Mar 2020 11:00:23 +0100 Message-ID: <20200305100023.GR16139@dhcp22.suse.cz> References: <20200304142348.48167-1-vincenzo.frascino@arm.com> <20200304165336.GO16139@dhcp22.suse.cz> <8c489836-b824-184e-7cfe-25e55ab73000@arm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <8c489836-b824-184e-7cfe-25e55ab73000-5wv7dgnIgG8@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="utf-8" To: Vincenzo Frascino Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Johannes Weiner , Vladimir Davydov , Andrew Morton On Thu 05-03-20 09:49:23, Vincenzo Frascino wrote: > Hi Michal, > > On 3/4/20 4:53 PM, Michal Hocko wrote: > > On Wed 04-03-20 14:23:48, Vincenzo Frascino wrote: > >> mem_cgroup_id_get_many() is currently used only when MMU or MEMCG_SWAP > >> configuration options are enabled. Having them disabled triggers the > >> following warning at compile time: > >> > >> linux/mm/memcontrol.c:4797:13: warning: ‘mem_cgroup_id_get_many’ defined > >> but not used [-Wunused-function] > >> static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned > >> int n) > >> > >> Make mem_cgroup_id_get_many() dependent on MMU and MEMCG_SWAP to address > >> the issue. > > > > A similar patch has been proposed recently > > http://lkml.kernel.org/r/87fthjh2ib.wl-kuninori.morimoto.gx-zM6kxYcvzFDowKkBSvOlow@public.gmane.org > > The conclusion was that the warning is not really worth adding code. > > > > Thank you for pointing this out, I was not aware of it. I understand that you > are against "#ifdeffery" in this case, but isn't it the case of adding at least > __maybe_unused? This would prevent people from reporting it over and over again > and you to have to push them back :) Let me know what do you think, in case I am > happy to change my patch accordingly. We have discussed __maybe_unused in the email thread as well. I am not a great fan of that as mentioed there. -- Michal Hocko SUSE Labs