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Violators will be prosecuted for from ; Wed, 31 Jul 2019 13:26:45 +0100 Date: Wed, 31 Jul 2019 15:26:32 +0300 From: Mike Rapoport Subject: Re: [PATCH v2 0/5] mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA References: <586ae736-a429-cf94-1520-1a94ffadad88@os.amperecomputing.com> <20190712121223.GR29483@dhcp22.suse.cz> <20190712143730.au3662g4ua2tjudu@willie-the-truck> <20190712150007.GU29483@dhcp22.suse.cz> <730368c5-1711-89ae-e3ef-65418b17ddc9@os.amperecomputing.com> <20190730081415.GN9330@dhcp22.suse.cz> <20190731062420.GC21422@rapoport-lnx> <20190731080309.GZ9330@dhcp22.suse.cz> <20190731111422.GA14538@rapoport-lnx> <20190731114016.GI9330@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190731114016.GI9330@dhcp22.suse.cz> Message-Id: <20190731122631.GB14538@rapoport-lnx> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Michal Hocko Cc: Hoan Tran OS , Will Deacon , Catalin Marinas , Heiko Carstens , "open list:MEMORY MANAGEMENT" , Paul Mackerras , "H . Peter Anvin" , "sparclinux@vger.kernel.org" , Alexander Duyck , "linux-s390@vger.kernel.org" , Michael Ellerman , "x86@kernel.org" , Christian Borntraeger , Ingo Molnar , Vlastimil Babka , Benjamin Herrenschmidt , Open Source Submission , Pavel Tatashin , Vasily Gorbik , Will Deacon , Borislav Petkov , Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" , Oscar Salvador , "linux-kernel@vger.kernel.org" , Andrew Morton , "linuxppc-dev@lists.ozlabs.org" , "David S . Miller" , "willy@infradead.org" On Wed, Jul 31, 2019 at 01:40:16PM +0200, Michal Hocko wrote: > On Wed 31-07-19 14:14:22, Mike Rapoport wrote: > > On Wed, Jul 31, 2019 at 10:03:09AM +0200, Michal Hocko wrote: > > > On Wed 31-07-19 09:24:21, Mike Rapoport wrote: > > > > [ sorry for a late reply too, somehow I missed this thread before ] > > > > > > > > On Tue, Jul 30, 2019 at 10:14:15AM +0200, Michal Hocko wrote: > > > > > [Sorry for a late reply] > > > > > > > > > > On Mon 15-07-19 17:55:07, Hoan Tran OS wrote: > > > > > > Hi, > > > > > > > > > > > > On 7/12/19 10:00 PM, Michal Hocko wrote: > > > > > [...] > > > > > > > Hmm, I thought this was selectable. But I am obviously wrong here. > > > > > > > Looking more closely, it seems that this is indeed only about > > > > > > > __early_pfn_to_nid and as such not something that should add a config > > > > > > > symbol. This should have been called out in the changelog though. > > > > > > > > > > > > Yes, do you have any other comments about my patch? > > > > > > > > > > Not really. Just make sure to explicitly state that > > > > > CONFIG_NODES_SPAN_OTHER_NODES is only about __early_pfn_to_nid and that > > > > > doesn't really deserve it's own config and can be pulled under NUMA. > > > > > > > > > > > > Also while at it, does HAVE_MEMBLOCK_NODE_MAP fall into a similar > > > > > > > bucket? Do we have any NUMA architecture that doesn't enable it? > > > > > > > > > > > > > > > HAVE_MEMBLOCK_NODE_MAP makes huge difference in node/zone initialization > > > > sequence so it's not only about a singe function. > > > > > > The question is whether we want to have this a config option or enable > > > it unconditionally for each NUMA system. > > > > We can make it 'default NUMA', but we can't drop it completely because > > microblaze uses sparse_memory_present_with_active_regions() which is > > unavailable when HAVE_MEMBLOCK_NODE_MAP=n. > > I suppose you mean that microblaze is using > sparse_memory_present_with_active_regions even without CONFIG_NUMA, > right? Yes. > I have to confess I do not understand that code. What is the deal > with setting node id there? The sparse_memory_present_with_active_regions() iterates over memblock.memory regions and uses the node id of each region as the parameter to memory_present(). The assumption here is that sometime before each region was assigned a proper non-negative node id. microblaze uses device tree for memory enumeration and the current FDT code does memblock_add() that implicitly sets nid in memblock.memory regions to -1. So in order to have proper node id passed to memory_present() microblaze has to call memblock_set_node() before it can use sparse_memory_present_with_active_regions(). > -- > Michal Hocko > SUSE Labs -- Sincerely yours, Mike.