On Tue, Jan 12, 2021 at 11:35:27PM -0800, Dan Williams wrote: > pfn_section_valid() determines pfn validity on subsection granularity > where pfn_valid() may be limited to coarse section granularity. > Explicitly validate subsections after pfn_valid() succeeds. > > Fixes: b13bc35193d9 ("mm/hotplug: invalid PFNs from pfn_to_online_page()") > Cc: Qian Cai <c...@lca.pw> > Cc: Michal Hocko <mho...@suse.com> > Cc: Oscar Salvador <osalva...@suse.de> > Reported-by: David Hildenbrand <da...@redhat.com> > Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
Reviewed-by: Oscar Salvador <osalva...@suse.de> > --- > mm/memory_hotplug.c | 24 ++++++++++++++++++++---- > 1 file changed, 20 insertions(+), 4 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 55a69d4396e7..9f37f8a68da4 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -308,11 +308,27 @@ static int check_hotplug_memory_addressable(unsigned > long pfn, > struct page *pfn_to_online_page(unsigned long pfn) > { > unsigned long nr = pfn_to_section_nr(pfn); > + struct mem_section *ms; > + > + if (nr >= NR_MEM_SECTIONS) > + return NULL; > + > + ms = __nr_to_section(nr); > + if (!online_section(ms)) > + return NULL; > + > + /* > + * Save some code text when online_section() + > + * pfn_section_valid() are sufficient. > + */ > + if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID)) > + if (!pfn_valid(pfn)) > + return NULL; > + > + if (!pfn_section_valid(ms, pfn)) > + return NULL; > > - if (nr < NR_MEM_SECTIONS && online_section_nr(nr) && > - pfn_valid_within(pfn)) > - return pfn_to_page(pfn); > - return NULL; > + return pfn_to_page(pfn); > } > EXPORT_SYMBOL_GPL(pfn_to_online_page); > > -- Oscar Salvador SUSE L3