On Thu 26-04-18 11:58:34, Pavel Tatashin wrote: > Memory hotplug, and hotremove operate with per-block granularity. If > machine has large amount of memory (more than 64G), the size of memory > block can span multiple sections. By mistake, during hotremove we set > only the first section to offline state. > > The bug was discovered because kernel selftest started to fail: > https://lkml.kernel.org/r/20180423011247.GK5563@yexl-desktop > > After commit, "mm/memory_hotplug: optimize probe routine". But, the bug is > older than this commit. In this optimization we also added a check for > sections to be in a proper state during hotplug operation. > > Fixes: 2d070eab2e82 ("mm: consider zone which is not fully populated to have holes") Dohh. When I saw this I've had that feeling that I have fixed this already and it must have get lost somewhere. But no, this was the same bug in a different path b4ccec41af82 ("mm/sparse.c: fix typo in online_mem_sections"). I wonder why I haven't noticed the same pattern in the offline path. Thanks for noticing and fixing this. > Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > mm/sparse.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index 62eef264a7bd..73dc2fcc0eab 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -629,7 +629,7 @@ void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn) > unsigned long pfn; > > for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { > - unsigned long section_nr = pfn_to_section_nr(start_pfn); > + unsigned long section_nr = pfn_to_section_nr(pfn); > struct mem_section *ms; > > /* > -- > 1.8.3.1 > -- Michal Hocko SUSE Labs
