On Mon, Jan 4, 2021 at 7:59 AM Michal Hocko <mhocko@xxxxxxxx> wrote: > > On Mon 04-01-21 16:43:49, 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. > > Exactly! > > > Let's assume this is indeed a reserved pfn in the altmap. What's the > > actual address of the memmap? > > Not sure what exactly you are asking for but crash says > crash> kmem -p 6060000 > PAGE PHYSICAL MAPPING INDEX CNT FLAGS > fffff8c600181800 6060000 0 0 0 fffffc0000000 > > > 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? > > I am not really familiar with the pmem so I would need more assistance > here. I've tried this (shot into the dark): > crash> struct page.pgmap fffff8c600181800 > pgmap = 0xfffff8c600181808 Does /proc/iomem show an active namespace in the range? You should be able to skip ahead to the first pfn in that namespace to find the first dev_pagemap. I would have expected pfn_to_online_page() to have saved you here. This address range is section aligned.
