On Wed 01-04-20 10:51:55, Mike Rapoport wrote: > Hi, > > On Wed, Apr 01, 2020 at 01:42:27PM +0800, Baoquan He wrote: [...] > > From above information, we can remove HAVE_MEMBLOCK_NODE_MAP, and > > replace it with CONFIG_NUMA. That sounds more sensible to store nid into > > memblock when NUMA support is enabled. > > Replacing CONFIG_HAVE_MEMBLOCK_NODE_MAP with CONFIG_NUMA will work, but > this will not help cleaning up the whole node/zone initialization mess and > we'll be stuck with two implementations. Yeah, this is far from optimal. > The overhead of enabling HAVE_MEMBLOCK_NODE_MAP is only for init time as > most architectures will anyway discard the entire memblock, so having it in > a UMA arch won't be a problem. The only exception is arm that uses > memblock for pfn_valid(), here we may also think about a solution to > compensate the addition of nid to the memblock structures. Well, we can make memblock_region->nid defined only for CONFIG_NUMA. memblock_get_region_node would then unconditionally return 0 on UMA. Essentially the same way we do NUMA for other MM code. I only see few direct usage of region->nid. -- Michal Hocko SUSE Labs
