We might use the nid of memmaps that were never initialized. For
example, if the memmap was poisoned, we will crash the kernel in
pfn_to_nid() right now. Let's use the calculated boundaries of the separate
zones instead. This now also avoids having to iterate over a whole bunch of
subsections again, after shrinking one zone.
Before commit d0dc12e86b31 ("mm/memory_hotplug: optimize memory
hotplug"), the memmap was initialized to 0 and the node was set to the
right value. After that commit, the node might be garbage.
We'll have to fix shrink_zone_span() next.
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Fixes: d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug")
Reported-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/memory_hotplug.c | 72 ++++++++++-----------------------------------
1 file changed, 15 insertions(+), 57 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 680b4b3e57d9..86b4dc18e831 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -436,67 +436,25 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
zone_span_writeunlock(zone);
}
-static void shrink_pgdat_span(struct pglist_data *pgdat,
- unsigned long start_pfn, unsigned long end_pfn)
+static void update_pgdat_span(struct pglist_data *pgdat)
{
- unsigned long pgdat_start_pfn = pgdat->node_start_pfn;
- unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */
- unsigned long pgdat_end_pfn = p;
- unsigned long pfn;
- int nid = pgdat->node_id;
-
- if (pgdat_start_pfn == start_pfn) {
- /*
- * If the section is smallest section in the pgdat, it need
- * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages.
- * In this case, we find second smallest valid mem_section
- * for shrinking zone.
- */
- pfn = find_smallest_section_pfn(nid, NULL, end_pfn,
- pgdat_end_pfn);
- if (pfn) {
- pgdat->node_start_pfn = pfn;
- pgdat->node_spanned_pages = pgdat_end_pfn - pfn;
- }
- } else if (pgdat_end_pfn == end_pfn) {
- /*
- * If the section is biggest section in the pgdat, it need
- * shrink pgdat->node_spanned_pages.
- * In this case, we find second biggest valid mem_section for
- * shrinking zone.
- */
- pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn,
- start_pfn);
- if (pfn)
- pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1;
- }
-
- /*
- * If the section is not biggest or smallest mem_section in the pgdat,
- * it only creates a hole in the pgdat. So in this case, we need not
- * change the pgdat.
- * But perhaps, the pgdat has only hole data. Thus it check the pgdat
- * has only hole or not.
- */
- pfn = pgdat_start_pfn;
- for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SUBSECTION) {
- if (unlikely(!pfn_valid(pfn)))
- continue;
-
- if (pfn_to_nid(pfn) != nid)
- continue;
+ unsigned long node_start_pfn = 0, node_end_pfn = 0;
+ struct zone *zone;
- /* Skip range to be removed */
- if (pfn >= start_pfn && pfn < end_pfn)
- continue;
+ for (zone = pgdat->node_zones;
+ zone < pgdat->node_zones + MAX_NR_ZONES; zone++) {
+ unsigned long zone_end_pfn = zone->zone_start_pfn +
+ zone->spanned_pages;
- /* If we find valid section, we have nothing to do */
- return;
+ /* No need to lock the zones, they can't change. */
+ if (zone_end_pfn > node_end_pfn)
+ node_end_pfn = zone_end_pfn;
+ if (zone->zone_start_pfn < node_start_pfn)
+ node_start_pfn = zone->zone_start_pfn;
}
- /* The pgdat has no valid section */
- pgdat->node_start_pfn = 0;
- pgdat->node_spanned_pages = 0;
+ pgdat->node_start_pfn = node_start_pfn;
+ pgdat->node_spanned_pages = node_end_pfn - node_start_pfn;
}
static void __remove_zone(struct zone *zone, unsigned long start_pfn,
@@ -507,7 +465,7 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn,
pgdat_resize_lock(zone->zone_pgdat, &flags);
shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
- shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages);
+ update_pgdat_span(pgdat);
pgdat_resize_unlock(zone->zone_pgdat, &flags);
}
--
2.21.0
