Re: [PATCH -mm] mm, pagemap: Fix swap offset value for PMD migration entry

[Andrew Morton]

On Sun,  8 Apr 2018 11:37:37 +0800 "Huang, Ying" <ying.huang@xxxxxxxxx> wrote:

> From: Huang Ying <ying.huang@xxxxxxxxx>
> 
> The swap offset reported by /proc/<pid>/pagemap may be not correct for
> PMD migration entry.  If addr passed into pagemap_range() isn't

pagemap_pmd_range(), yes?

> aligned with PMD start address,

How can this situation come about?

> the swap offset reported doesn't
> reflect this.  And in the loop to report information of each sub-page,
> the swap offset isn't increased accordingly as that for PFN.
> 
> BTW: migration swap entries have PFN information, do we need to
> restrict whether to show them?

For what reason?  Address obfuscation?