On Wed, May 11, 2022 at 05:11:17PM +0200, David Hildenbrand wrote: > On 09.05.22 12:53, Miaohe Lin wrote: > > On 2022/5/9 17:58, Oscar Salvador wrote: > >> On Mon, May 09, 2022 at 05:04:54PM +0800, Miaohe Lin wrote: > >>>>> So that leaves us with either > >>>>> > >>>>> 1) Fail offlining -> no need to care about reonlining > >>> > >>> Maybe fail offlining will be a better alternative as we can get rid of many races > >>> between memory failure and memory offline? But no strong opinion. :) > >> > >> If taking care of those races is not an herculean effort, I'd go with > >> allowing offlining + disallow re-onlining. > >> Mainly because memory RAS stuff. > > > > This dose make sense to me. Thanks. We can try to solve those races if > > offlining + disallow re-onlining is applied. :) > > > >> > >> Now, to the re-onlining thing, we'll have to come up with a way to check > >> whether a section contains hwpoisoned pages, so we do not have to go > >> and check every single page, as that will be really suboptimal. > > > > Yes, we need a stable and cheap way to do that. > > My simplistic approach would be a simple flag/indicator in the memory block devices > that indicates that any page in the memory block was hwpoisoned. It's easy to > check that during memory onlining and fail it. > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index 084d67fd55cc..3d0ef812e901 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -183,6 +183,9 @@ static int memory_block_online(struct memory_block *mem) > struct zone *zone; > int ret; > > + if (mem->hwpoisoned) > + return -EHWPOISON; > + > zone = zone_for_pfn_range(mem->online_type, mem->nid, mem->group, > start_pfn, nr_pages); > Thanks for the idea, a simple flag could work if we don't have to consider unpoison. If we need consider unpoison, we need remember the last hwpoison page in the memory block, so mem->hwpoisoned should be the counter of hwpoison pages. > > > Once the problematic DIMM would actually get unplugged, the memory block devices > would get removed as well. So when hotplugging a new DIMM in the same > location, we could online that memory again. What about PG_hwpoison flags? struct pages are also freed and reallocated in the actual DIMM replacement? Thanks, Naoya Horiguchi > > Another place to store that would be the memory section, we'd then have to check > all underlying sections here. > > We're a bit short on flags in the memory section I think, but they are easier to > lookup from other code eventually then memory block devices.
