pfn_section_valid() determines pfn validity on subsection granularity.
pfn_valid_within() internally uses pfn_section_valid(), but gates it
with early_section() to preserve the traditional behavior of pfn_valid()
before subsection support was added.
pfn_to_online_page() wants the explicit precision that pfn_valid() does
not offer, so use pfn_section_valid() directly. Since
pfn_to_online_page() already open codes the validity of the section
number vs NR_MEM_SECTIONS, there's not much value to using
pfn_valid_within(), just use pfn_section_valid(). This loses the
valid_section() check that pfn_valid_within() was performing, but that
was already redundant with the online check.
Fixes: b13bc35193d9 ("mm/hotplug: invalid PFNs from pfn_to_online_page()")
Cc: Qian Cai <cai@xxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Reported-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/memory_hotplug.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 55a69d4396e7..a845b3979bc0 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -308,11 +308,19 @@ 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;
+
+ 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);
