From: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Subject: mm: sections are not offlined during memory hotremove Memory hotplug and hotremove operate with per-block granularity. If the machine has a large amount of memory (more than 64G), the size of a memory block can span multiple sections. By mistake, during hotremove we set only the first section to offline state. The bug was discovered because kernel selftest started to fail: https://lkml.kernel.org/r/20180423011247.GK5563@yexl-desktop After commit, "mm/memory_hotplug: optimize probe routine". But, the bug is older than this commit. In this optimization we also added a check for sections to be in a proper state during hotplug operation. Link: http://lkml.kernel.org/r/20180427145257.15222-1-pasha.tatashin@xxxxxxxxxx Fixes: 2d070eab2e82 ("mm: consider zone which is not fully populated to have holes") Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Steven Sistare <steven.sistare@xxxxxxxxxx> Cc: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/sparse.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN mm/sparse.c~mm-sections-are-not-offlined-during-memory-hotremove mm/sparse.c --- a/mm/sparse.c~mm-sections-are-not-offlined-during-memory-hotremove +++ a/mm/sparse.c @@ -629,7 +629,7 @@ void offline_mem_sections(unsigned long unsigned long pfn; for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { - unsigned long section_nr = pfn_to_section_nr(start_pfn); + unsigned long section_nr = pfn_to_section_nr(pfn); struct mem_section *ms; /* _
