Alistair Popple wrote:

GUP uses pXX_devmap() calls to see if it needs to a get a reference on
the associated pgmap data structure to ensure the pages won't go
away. However it's a driver responsibility to ensure that if pages are
mapped (ie. discoverable by GUP) that they are not offlined or removed
from the memmap so there is no need to hold a reference on the pgmap
data structure to ensure this.

Furthermore mappings with PFN_DEV are no longer created, hence this
effectively dead code anyway so can be removed.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 include/linux/huge_mm.h |   3 +-
 mm/gup.c                | 162 +----------------------------------------
 mm/huge_memory.c        |  40 +----------
 3 files changed, 5 insertions(+), 200 deletions(-)

Hooray! Goodbye dev_pagemap mess in gup.c.

Reviewed-by: Dan Williams <redacted>