On Tue 12-03-19 16:35:06, Oscar Salvador wrote: [...] > One thing I noticed when looking at start_isolate_page_range and > undo_isolate_page_range functions, is that start_isolate_page_range increments > the number of isolated pageblocks, while undo_isolate_page_range does the counter > part. > Since undo_isolate_page_range is really never called during offlining, > we leave zone->nr_isolate_pageblock with a stale value. > > I __think__ this does not matter much. > We only get to check whether a zone got isolated pageblocks in > has_isolate_pageblock(), and this is called from: > > free_one_page > free_pcppages_bulk > __free_one_page It forces those into slow(er) path. So it makes a difference. > With a quick glance, the only difference in has_isolate_pageblock() returning > true or false, seems to be that those functions perform some extra checks in > case the zone reports to have isolated pageblocks. > > I wonder if we should set nr_isolate_pageblock back to its original value > before start_isolate_page_range. Yes. And that would be a fixup to my 2ce13640b3f4. -- Michal Hocko SUSE Labs
