On Fri 28-04-17 08:50:50, Michal Hocko wrote: > [Drop Wen Congyang because his address bounces - we will have to find > out ourselves...] Ble, for real this time. Sorry about spamming > On Fri 28-04-17 08:30:48, Michal Hocko wrote: > > On Wed 26-04-17 03:13:04, Naoya Horiguchi wrote: > > > On Wed, Apr 26, 2017 at 12:10:15PM +1000, Balbir Singh wrote: > > > > On Tue, 2017-04-25 at 16:27 +0200, Laurent Dufour wrote: > > > > > The commit b023f46813cd ("memory-hotplug: skip HWPoisoned page when > > > > > offlining pages") skip the HWPoisoned pages when offlining pages, but > > > > > this should be skipped when onlining the pages too. > > > > > > > > > > Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx> > > > > > --- > > > > > mm/memory_hotplug.c | 4 ++++ > > > > > 1 file changed, 4 insertions(+) > > > > > > > > > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > > > > > index 6fa7208bcd56..741ddb50e7d2 100644 > > > > > --- a/mm/memory_hotplug.c > > > > > +++ b/mm/memory_hotplug.c > > > > > @@ -942,6 +942,10 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, > > > > > if (PageReserved(pfn_to_page(start_pfn))) > > > > > for (i = 0; i < nr_pages; i++) { > > > > > page = pfn_to_page(start_pfn + i); > > > > > + if (PageHWPoison(page)) { > > > > > + ClearPageReserved(page); > > > > > > > > Why do we clear page reserved? Also if the page is marked PageHWPoison, it > > > > was never offlined to begin with? Or do you expect this to be set on newly > > > > hotplugged memory? Also don't we need to skip the entire pageblock? > > > > > > If I read correctly, to "skip HWPoiosned page" in commit b023f46813cd means > > > that we skip the page status check for hwpoisoned pages *not* to prevent > > > memory offlining for memblocks with hwpoisoned pages. That means that > > > hwpoisoned pages can be offlined. > > > > Is this patch actually correct? I am trying to wrap my head around it > > but it smells like it tries to avoid the problem rather than fix it > > properly. I might be wrong here of course but to me it sounds like > > poisoned page should simply be offlined and keep its poison state all > > the time. If the memory is hot-removed and added again we have lost the > > struct page along with the state which is the expected behavior. If it > > is still broken we will re-poison it. > > > > Anyway a patch to skip over poisoned pages during online makes perfect > > sense to me. The PageReserved fiddling around much less so. > > > > Or am I missing something. Let's CC Wen Congyang for the clarification > > here. > > -- > Michal Hocko > SUSE Labs -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>