From: Oscar Salvador <osalvador@xxxxxxx> Subject: mm/memory_hotplug.c: call register_mem_sect_under_node() When hotplugging memory, it is possible that two calls are being made to register_mem_sect_under_node(). One comes from __add_section()->hotplug_memory_register() and the other from add_memory_resource()->link_mem_sections() if we had to register a new node. In case we had to register a new node, hotplug_memory_register() will only handle/allocate the memory_block's since register_mem_sect_under_node() will return right away because the node it is not online yet. I think it is better if we leave hotplug_memory_register() to handle/allocate only memory_block's and make link_mem_sections() to call register_mem_sect_under_node(). So this patch removes the call to register_mem_sect_under_node() from hotplug_memory_register(), and moves the call to link_mem_sections() out of the condition, so it will always be called. In this way we only have one place where the memory sections are registered. Link: http://lkml.kernel.org/r/20180622111839.10071-3-osalvador@xxxxxxxxxxxxxxxxxx Signed-off-by: Oscar Salvador <osalvador@xxxxxxx> Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Tested-by: Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx> Tested-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> Cc: Pasha Tatashin <Pavel.Tatashin@xxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/base/memory.c | 2 -- mm/memory_hotplug.c | 32 +++++++++++--------------------- 2 files changed, 11 insertions(+), 23 deletions(-) --- a/drivers/base/memory.c~mm-memory_hotplug-call-register_mem_sect_under_node +++ a/drivers/base/memory.c @@ -736,8 +736,6 @@ int hotplug_memory_register(int nid, str mem->section_count++; } - if (mem->section_count == sections_per_block) - ret = register_mem_sect_under_node(mem, nid, false); out: mutex_unlock(&mem_sysfs_mutex); return ret; --- a/mm/memory_hotplug.c~mm-memory_hotplug-call-register_mem_sect_under_node +++ a/mm/memory_hotplug.c @@ -1123,6 +1123,7 @@ int __ref add_memory_resource(int nid, s u64 start, size; bool new_node = false; int ret; + unsigned long start_pfn, nr_pages; start = res->start; size = resource_size(res); @@ -1151,34 +1152,23 @@ int __ref add_memory_resource(int nid, s if (ret < 0) goto error; - /* we online node here. we can't roll back from here. */ - node_set_online(nid); - if (new_node) { - unsigned long start_pfn = start >> PAGE_SHIFT; - unsigned long nr_pages = size >> PAGE_SHIFT; - - ret = __register_one_node(nid); - if (ret) - goto register_fail; - - /* - * link memory sections under this node. This is already - * done when creatig memory section in register_new_memory - * but that depends to have the node registered so offline - * nodes have to go through register_node. - * TODO clean up this mess. - */ - ret = link_mem_sections(nid, start_pfn, nr_pages, false); -register_fail: - /* - * If sysfs file of new node can't create, cpu on the node + /* If sysfs file of new node can't be created, cpu on the node * can't be hot-added. There is no rollback way now. * So, check by BUG_ON() to catch it reluctantly.. + * We online node here. We can't roll back from here. */ + node_set_online(nid); + ret = __register_one_node(nid); BUG_ON(ret); } + /* link memory sections under this node.*/ + start_pfn = start >> PAGE_SHIFT; + nr_pages = size >> PAGE_SHIFT; + ret = link_mem_sections(nid, start_pfn, nr_pages, false); + BUG_ON(ret); + /* create new memmap entry */ firmware_map_add_hotplug(start, start + size, "System RAM"); _