On Thu, Mar 18, 2021 at 12:24:16PM +0100, David Hildenbrand wrote: > I don't follow. 2MB == 2MB. And if there would be difference then we would > be in the problem I brought up: vmemmap code allocating too much via the > altmap, which can be very bad because might be populating more vmemmap than > we actually need. Yes, I meant to say nr_vmemmap_pages won't match, or IOW, won't have the same meaning. The end result is the same. > vmemmap_size = 512 * 4KiB = 2 MiB. > > That calculation wasn't very useful (/ PAGE_SIZE * PAGE_SIZE)? Yeah, somewhat redundant. > > > unsigned long remaining_size = size - vmemmap_size; > > And here we could get something like > > remaining_size = 2 GiB - 2 MiB Yes, vmemmap_size would need to scale with nr_sections to be relative to size. Just wanted to bring it up, because somene might wonder "ok, why do we have altmap->nr_pfns = X, and here nr_vmemmap_pages is Y" It was an effort to make it consistent, although I see it would bring more confusion other than anything, so disregard. -- Oscar Salvador SUSE L3
