Re: [PATCH v2 2/3] mm: calculate deferred pages after skipping mirrored memory

[Pavel Tatashin <pasha.tatashin@oracle.com>]

                         unsigned long *nr_initialised)
> > +static bool __meminit
> > +defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
>
> Hi Pavel,
>
> maybe I do not understand properly the __init/__meminit macros, but should not
> "defer_init" be __init instead of __meminit?
> I think that functions marked as __meminit are not freed up, right?

Not exactly. As I understand: __meminit is the same as __init when
CONFIG_MEMORY_HOTPLUG=n. But, when memory hotplug is configured,
__meminit is not freed, because code that adds memory is shared
between boot and hotplug. In this case defer_init() is called only
during boot, and could be __init, but it is called from
memmap_init_zone() which is __meminit and thus section mismatch would
happen.

We could split memmap_init_zone() into two functions: boot and hotplug
variants, or we could use __ref, but I do not think any of that is
really needed. Keeping defer_init() in __meminit is OK, it does not
take that much memory.

>
> Reviewed-by: Oscar Salvador <osalvador@suse.de>

Thank you,
Pavel