In add_memory_resource() the memory range to be hot added first gets into the memblock via memblock_add() before arch_add_memory() is called on it. Reverse sequence should be followed during memory hot removal which already is being followed in add_memory_resource() error path. This now ensures required re-order between memblock_[free|remove]() and arch_remove_memory() during memory hot-remove. Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Oscar Salvador <osalvador@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> --- Original patch https://lkml.org/lkml/2019/9/3/327 Memory hot remove now works on arm64 without this because a recent commit 60bb462fc7ad ("drivers/base/node.c: simplify unregister_memory_block_under_nodes()"). David mentioned that re-ordering should still make sense for consistency purpose (removing stuff in the reverse order they were added). This patch is now detached from arm64 hot-remove series. https://lkml.org/lkml/2019/9/3/326 mm/memory_hotplug.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index c73f09913165..355c466e0621 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1770,13 +1770,13 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size) /* remove memmap entry */ firmware_map_remove(start, start + size, "System RAM"); - memblock_free(start, size); - memblock_remove(start, size); /* remove memory block devices before removing memory */ remove_memory_block_devices(start, size); arch_remove_memory(nid, start, size, NULL); + memblock_free(start, size); + memblock_remove(start, size); __release_memory_resource(start, size); try_offline_node(nid); -- 2.20.1
