5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zi Yan <ziy@xxxxxxxxxx> commit 1640a0ef80f6d572725f5b0330038c18e98ea168 upstream. When dealing with hugetlb pages, manipulating struct page pointers directly can get to wrong struct page, since struct page is not guaranteed to be contiguous on SPARSEMEM without VMEMMAP. Use pfn calculation to handle it properly. Without the fix, a wrong number of page might be skipped. Since skip cannot be negative, scan_movable_page() will end early and might miss a movable page with -ENOENT. This might fail offline_pages(). No bug is reported. The fix comes from code inspection. Link: https://lkml.kernel.org/r/20230913201248.452081-4-zi.yan@xxxxxxxx Fixes: eeb0efd071d8 ("mm,memory_hotplug: fix scan_movable_pages() for gigantic hugepages") Signed-off-by: Zi Yan <ziy@xxxxxxxxxx> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Acked-by: David Hildenbrand <david@xxxxxxxxxx> Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/memory_hotplug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1677,7 +1677,7 @@ static int scan_movable_pages(unsigned l */ if (HPageMigratable(head)) goto found; - skip = compound_nr(head) - (page - head); + skip = compound_nr(head) - (pfn - page_to_pfn(head)); pfn += skip - 1; } return -ENOENT;
