mm: pgtable: add missing pt_index to struct ptdesc

In s390, the page->index field is used for gmap (see gmap_shadow_pgt()),
so add the corresponding pt_index to struct ptdesc and add a comment to
clarify this.

Link: https://lkml.kernel.org/r/283624c2af45fb2090b41a6b1b5481bb0a45bad7.1709541697.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Claudio Imbrenda <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Janosch Frank <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions