Re: [PATCH 06/12] mm/gup: Remove pXX_devmap usage from get_user_pages()

Dan Williams
2025-06-05T02:06:42Z

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 <dan.j.williams@intel.com>