[RFC][PATCH 00/12] mm: tweak page cache migration

[Dave Hansen]

First of all, I think this little slice of code is a bit
under-documented.  Perhaps this will help clarify things.

I'm pretty confident the page_count() check in the first
patch is right, which is why I removed it outright.  The
xas_load() check is a bit murkier, so I just left a
warning in for it.

Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx