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[213.151.95.130]) by smtp.gmail.com with ESMTPSA id a13sm5808318wrt.55.2020.02.25.02.02.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Feb 2020 02:02:26 -0800 (PST) Date: Tue, 25 Feb 2020 11:02:26 +0100 From: Michal Hocko To: David Hildenbrand Cc: Baoquan He , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, richardw.yang@linux.intel.com, osalvador@suse.de, dan.j.williams@intel.com, rppt@linux.ibm.com, robin.murphy@arm.com Subject: Re: [PATCH v2 0/7] mm/hotplug: Only use subsection map in VMEMMAP case Message-ID: <20200225100226.GM22443@dhcp22.suse.cz> References: <20200220043316.19668-1-bhe@redhat.com> <20200220103849.GG20509@dhcp22.suse.cz> <20200221142847.GG4937@MiWiFi-R3L-srv> <75b4f840-7454-d6d0-5453-f0a045c852fa@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <75b4f840-7454-d6d0-5453-f0a045c852fa@redhat.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 25-02-20 10:10:45, David Hildenbrand wrote: > >>> include/linux/mmzone.h | 2 + > >>> mm/sparse.c | 178 +++++++++++++++++++++++++++++------------ > >>> 2 files changed, 127 insertions(+), 53 deletions(-) > >> > >> Why do we need to add so much code to remove a functionality from one > >> memory model? > > > > Hmm, Dan also asked this before. > > > > The adding mainly happens in patch 2, 3, 4, including the two newly > > added function defitions, the code comments above them, and those added > > dummy functions for !VMEMMAP. > > AFAIKS, it's mostly a bunch of newly added comments on top of functions. > E.g., the comment for fill_subsection_map() alone spans 12 LOC in total. > I do wonder if we have to be that verbose. We are barely that verbose on > MM code (and usually I don't see much benefit unless it's a function > with many users from many different places). I would tend to agree here. Not that I am against kernel doc documentation but these are internal functions and the comment doesn't really give any better insight IMHO. I would be much more inclined if this was the general pattern in the respective file but it just stands out. -- Michal Hocko SUSE Labs