On Fri,  1 Jun 2018 14:53:18 +0200 [email protected] wrote:

> From: Oscar Salvador <[email protected]>
> 
> add_memory_resource() contains code to allocate a new node in case
> it is necessary.
> Since try_online_node() also hast some code for this purpose,
> let us make use of that and remove duplicate code.
> 
> This introduces __try_online_node(), which is called by add_memory_resource()
> and try_online_node().
> __try_online_node() has two new parameters, start_addr of the node,
> and if the node should be onlined and registered right away.
> This is always wanted if we are calling from do_cpu_up(), but not
> when we are calling from memhotplug code.
> Nothing changes from the point of view of the users of try_online_node(),
> since try_online_node passes start_addr=0 and online_node=true to
> __try_online_node().
> 
> ...
>
> @@ -1126,17 +1136,14 @@ int __ref add_memory_resource(int nid, struct 
> resource *res, bool online)
>        */
>       memblock_add_node(start, size, nid);
>  
> -     new_node = !node_online(nid);
> -     if (new_node) {
> -             pgdat = hotadd_new_pgdat(nid, start);
> -             ret = -ENOMEM;
> -             if (!pgdat)
> -                     goto error;
> -     }
> +     ret = __try_online_node (nid, start, false);
> +     new_node = !!(ret > 0);

I don't think __try_online_node() will ever return a value greater than
zero.  I assume what was meant was

        new_node = !!(ret >= 0);

which may as well be

        new_node = (ret >= 0);

since both sides have bool type.

The fact that testing didn't detect this is worrisome....

> +     if (ret < 0)
> +             goto error;
> +
>  
>       /* call arch's memory hotadd */
>       ret = arch_add_memory(nid, start, size, NULL, true);
> -
>       if (ret < 0)
>               goto error;
>  
> 
> ...
>

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