The patch titled
Subject: mm/memory_hotplug: fix updating the node span
has been added to the -mm tree. Its filename is
mm-memory_hotplug-fix-updating-the-node-span.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-fix-updating-the-node-span.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory_hotplug-fix-updating-the-node-span.patch
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/memory_hotplug: fix updating the node span
We recently started updating the node span based on the zone span to avoid
touching uninitialized memmaps.
Currently, we will always detect the node span to start at 0, meaning a
node can easily span too many pages. pgdat_is_empty() will still work
correctly if all zones span no pages. We should skip over all zones
without spanned pages and properly handle the first detected zone that
spans pages.
Unfortunately, in contrast to the zone span (/proc/zoneinfo), the node
span cannot easily be inspected and tested. The node span gives no real
guarantees when an architecture supports memory hotplug, meaning it can
easily contain holes or span pages of different nodes.
The node span is not really used after init on architectures that support
memory hotplug. E.g., we use it in mm/memory_hotplug.c:try_offline_node()
and in mm/kmemleak.c:kmemleak_scan(). These users seem to be fine.
Link: http://lkml.kernel.org/r/20191027222714.5313-1-david@xxxxxxxxxx
Fixes: 00d6c019b5bc ("mm/memory_hotplug: don't access uninitialized memmaps in shrink_pgdat_span()")
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/mm/memory_hotplug.c~mm-memory_hotplug-fix-updating-the-node-span
+++ a/mm/memory_hotplug.c
@@ -447,6 +447,14 @@ static void update_pgdat_span(struct pgl
zone->spanned_pages;
/* No need to lock the zones, they can't change. */
+ if (!zone->spanned_pages)
+ continue;
+ if (!node_end_pfn) {
+ node_start_pfn = zone->zone_start_pfn;
+ node_end_pfn = zone_end_pfn;
+ continue;
+ }
+
if (zone_end_pfn > node_end_pfn)
node_end_pfn = zone_end_pfn;
if (zone->zone_start_pfn < node_start_pfn)
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-memory_hotplug-fix-updating-the-node-span.patch
mm-memory_hotplug-export-generic_online_page.patch
hv_balloon-use-generic_online_page.patch
mm-memory_hotplug-remove-__online_page_free-and-__online_page_increment_counters.patch
mm-memory_hotplug-dont-access-uninitialized-memmaps-in-shrink_zone_span.patch
mm-memory_hotplug-shrink-zones-when-offlining-memory.patch
mm-memory_hotplug-poison-memmap-in-remove_pfn_range_from_zone.patch
mm-memory_hotplug-we-always-have-a-zone-in-find_smallestbiggest_section_pfn.patch
mm-memory_hotplug-dont-check-for-all-holes-in-shrink_zone_span.patch
mm-memory_hotplug-drop-local-variables-in-shrink_zone_span.patch
mm-memory_hotplug-cleanup-__remove_pages.patch
mm-page_allocc-dont-set-pages-pagereserved-when-offlining.patch
mm-page_isolationc-convert-skip_hwpoison-to-memory_offline.patch
mm-memory_hotplug-fix-try_offline_node.patch
