On Wed 16-10-19 15:55:00, David Hildenbrand wrote: > On 16.10.19 15:45, Michal Hocko wrote: [...] > > There is state stored in the struct page. In other words this shouldn't > > be really different from HWPoison pages. I cannot find the code that is > > doing that and maybe we don't handle that. But we cannot simply online > > hwpoisoned page. Offlining the range will not make a broken memory OK > > all of the sudden. And your usecase sounds similar to me. > > Sorry to say, but whenever we online memory the memmap is overwritten, > because there is no way you could tell it contains garbage or not. You have > to assume it is garbage. (my recent patch even poisons the memmap when > offlining, which helped to find a lot of these "garbage memmap" BUGs) > > online_pages() > ... > move_pfn_range_to_zone(zone, pfn, nr_pages, NULL); > ... > memmap_init_zone() > -> memmap initialized > > So yes, offlining memory with HWPoison and re-onlining it effectively drops > HWPoison markers. On the next access, you will trigger a new HWPoison. Right you are! I need to sit on this much more and think about it with a clean head. -- Michal Hocko SUSE Labs
