On Wed, Apr 21, 2021 at 4:21 PM Oscar Salvador <osalvador@xxxxxxx> wrote: > > On Wed, Apr 21, 2021 at 04:15:00PM +0800, Muchun Song wrote: > > > The hwpoison side of this looks really suspicious to me. It shouldn't > > > really touch the reference count of hugetlb pages without being very > > > careful (and having hugetlb_lock held). What would happen if the > > > reference count was increased after the page has been enqueed into the > > > pool? This can just blow up later. > > > > If the page has been enqueued into the pool, then the page can be > > allocated to other users. The page reference count will be reset to > > 1 in the dequeue_huge_page_node_exact(). Then memory-failure > > will free the page because of put_page(). This is wrong. Because > > there is another user. > > Note that dequeue_huge_page_node_exact() will not hand over any pages > which are poisoned, so in this case it will not be allocated. But softoffline does not set page hwpoison before __get_hwpoison_page(). So the page still can be allocated. Right? > But it is true that we might need hugetlb lock, this needs some more > thought. > > I will have a look. > > -- > Oscar Salvador > SUSE L3
