Re: [PATCH 1/3] mm: document zone device struct page reserved fields

[Ralph Campbell <rcampbell@nvidia.com>]

On 7/16/19 9:38 PM, Christoph Hellwig wrote:
> On Tue, Jul 16, 2019 at 09:31:33PM -0700, John Hubbard wrote:
>> OK, so just delete all the _zd_pad_* fields? Works for me. It's misleading to
>> calling something padding, if it's actually unavailable because it's used
>> in the other union, so deleting would be even better than commenting.
>>
>> In that case, it would still be nice to have this new snippet, right?:
> 
> I hope willy can chime in a bit on his thoughts about how the union in
> struct page should look like.  The padding at the end of the sub-structs
> certainly looks pointless, and other places don't use it either.  But if
> we are using the other fields it almost seems to me like we only want to
> union the lru field in the first sub-struct instead of overlaying most
> of it.
>

I like this approach.
I'll work on an updated patch that makes "struct list_head lru" part
of a union with the ZONE_DEVICE struct without the padding and update
the comments and change log.

I will also wait a day or two for others to add their comments.