On Thu, Sep 22, 2022 at 09:31:12AM -0500, Tom Lendacky wrote: > On 9/8/22 14:28, Mike Rapoport wrote: > > On Thu, Sep 08, 2022 at 09:23:07AM -0700, Dionna Amalie Glaze wrote: > > > > > > > > Looks like the first access to the memory map fails, although I think > > > > it's not in INIT_LIST_HEAD() but rather in init_page_count(). > > > > > > > > I'd start with making sure that page_alloc::memmap_alloc() actually returns > > > > accepted memory. If you build kernel with CONFIG_DEBUG_VM=y the memory map > > > > will poisoned in this function, so my guess is it'd crash there. > > > > > > > > > > That's a wonderful hint, thank you! I did not run this test > > > CONFIG_DEBUG_VM set, but you think it's possible it could still be > > > here? > > > > It depends on how you configured your kernel. Say, defconfig does not set > > it. > > > > I also hit the issue at 256GB. My config is using CONFIG_SPARSEMEM_VMEMMAP > and fails in memmap_init_range() when attempting to add the first PFN. It > looks like the underlying page that is backing the vmemmap has not been > accepted (I receive a #VC 0x404 => page not validated). > > Kirill, is this a path that you've looked at? It would appear that somewhere > in the vmemmap_populate_hugepages() path, some memory acceptance needs to be > done for the pages that are used to back vmemmap. I'm not very familiar with > this code, so I'm not sure why everything works for a guest with 255GB of > memory, but then fails for a guest with 256GB of memory. Hm. I don't have machine that large at hands at the moment. And I have not looked at the codepath before. I will try to look into the issue. -- Kiryl Shutsemau / Kirill A. Shutemov
