On 04.01.21 16:43, David Hildenbrand wrote: > On 04.01.21 16:33, Michal Hocko wrote: >> On Mon 04-01-21 16:15:23, David Hildenbrand wrote: >>> On 04.01.21 16:10, Michal Hocko wrote: >> [...] >>> Do the physical addresses you see fall into the same section as boot >>> memory? Or what's around these addresses? >> >> Yes I am getting a garbage for the first struct page belonging to the >> pmem section [1] >> [ 0.020161] ACPI: SRAT: Node 0 PXM 0 [mem 0x100000000-0x603fffffff] >> [ 0.020163] ACPI: SRAT: Node 4 PXM 4 [mem 0x6060000000-0x11d5fffffff] non-volatile >> >> The pfn without the initialized struct page is 0x6060000. This is a >> first pfn in a section. > > Okay, so we're not dealing with the "early section" mess I described, > different story. > > Due to [1], is_mem_section_removable() called > pfn_to_page(PHYS_PFN(0x6060000)). page_zone(page) made it crash, as not > initialized. > > Let's assume this is indeed a reserved pfn in the altmap. What's the > actual address of the memmap? > > I do wonder what hosts pfn_to_page(PHYS_PFN(0x6060000)) - is it actually > part of the actual altmap (i.e. > 0x6060000) or maybe even self-hosted? > > If it's not self-hosted, initializing the relevant memmaps should work > just fine I guess. Otherwise things get more complicated. Oh, I forgot: pfn_to_online_page() should at least in your example make sure other pfn walkers are safe. It was just an issue of is_mem_section_removable(). -- Thanks, David / dhildenb
