The patch titled
Subject: mm/memory_hotplug: make sure the pfn is aligned to the order when onlining
has been added to the -mm tree. Its filename is
mm-memory_hotplug-make-sure-the-pfn-is-aligned-to-the-order-when-onlining.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-make-sure-the-pfn-is-aligned-to-the-order-when-onlining.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory_hotplug-make-sure-the-pfn-is-aligned-to-the-order-when-onlining.patch
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/memory_hotplug: make sure the pfn is aligned to the order when onlining
Commit a9cd410a3d29 ("mm/page_alloc.c: memory hotplug: free pages as
higher order") assumed that any PFN we get via memory resources is aligned
to to MAX_ORDER - 1, I am not convinced that is always true. Let's play
safe, check the alignment and fallback to single pages.
akpm: warn in this situation so we get to find out if and why this ever
occurs.
Link: http://lkml.kernel.org/r/20190814154109.3448-5-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Arun KS <arunks@xxxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Nadav Amit <namit@xxxxxxxxxx>
Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 3 +++
1 file changed, 3 insertions(+)
--- a/mm/memory_hotplug.c~mm-memory_hotplug-make-sure-the-pfn-is-aligned-to-the-order-when-onlining
+++ a/mm/memory_hotplug.c
@@ -646,6 +646,9 @@ static int online_pages_range(unsigned l
*/
for (pfn = start_pfn; pfn < end_pfn; pfn += 1ul << order) {
order = min(MAX_ORDER - 1, get_order(PFN_PHYS(end_pfn - pfn)));
+ /* __free_pages_core() wants pfns to be aligned to the order */
+ if (unlikely(!IS_ALIGNED(pfn, 1ul << order)))
+ order = 0;
(*online_page_callback)(pfn_to_page(pfn), order);
}
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-memory_hotplug-remove-move_pfn_range.patch
drivers-base-nodec-simplify-unregister_memory_block_under_nodes.patch
drivers-base-memoryc-fixup-documentation-of-removable-phys_index-block_size_bytes.patch
driver-base-memoryc-validate-memory-block-size-early.patch
drivers-base-memoryc-dont-store-end_section_nr-in-memory-blocks.patch
resource-use-pfn_up-pfn_down-in-walk_system_ram_range.patch
mm-memory_hotplug-drop-pagereserved-check-in-online_pages_range.patch
mm-memory_hotplug-simplify-online_pages_range.patch
mm-memory_hotplug-make-sure-the-pfn-is-aligned-to-the-order-when-onlining.patch
mm-memory_hotplug-online_pages-cannot-be-0-in-online_pages.patch
