On Mon 23-07-18 13:45:18, Vlastimil Babka wrote: > On 07/20/2018 02:34 PM, David Hildenbrand wrote: > > Dumping tools (like makedumpfile) right now don't exclude reserved pages. > > So reserved pages might be access by dump tools although nobody except > > the owner should touch them. > > Are you sure about that? Or maybe I understand wrong. Maybe it changed > recently, but IIRC pages that are backing memmap (struct pages) are also > PG_reserved. And you definitely do want those in the dump. You are right. reserve_bootmem_region will make all early bootmem allocations (including those backing memmaps) PageReserved. I have asked several times but I haven't seen a satisfactory answer yet. Why do we even care for kdump about those. If they are reserved the nobody should really look at those specific struct pages and manipulate them. Kdump tools are using a kernel interface to read the content. If the specific content is backed by a non-existing memory then they should simply not return anything. -- Michal Hocko SUSE Labs
