[PATCH] mm: fix misleading comment for remap_pfn_range()

[PATCH] mm: fix misleading comment for remap_pfn_range()

[Minu Jin]

The function summary describes this as remapping "kernel memory",
but remap_pfn_range() operates on arbitrary PFNs, including
device MMIO regions that are not kernel memory at all.

Replace with "physical address range".
It describes accurately what the function maps.

Signed-off-by: Minu Jin <s9430939@naver.com>
---
 mm/memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index ea6568571131..4e07e03a76a4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3172,7 +3172,7 @@ static int remap_pfn_range_prepare_vma(struct vm_area_struct *vma,
 }
 
 /**
- * remap_pfn_range - remap kernel memory to userspace
+ * remap_pfn_range - remap physical address range to user space
  * @vma: user vma to map to
  * @addr: target page aligned user address to start at
  * @pfn: page frame number of kernel physical memory address
-- 
2.43.0

Re: [PATCH] mm: fix misleading comment for remap_pfn_range()

[Lorenzo Stoakes]

On Tue, May 12, 2026 at 11:35:43PM +0900, Minu Jin wrote:
> The function summary describes this as remapping "kernel memory",
> but remap_pfn_range() operates on arbitrary PFNs, including
> device MMIO regions that are not kernel memory at all.
>
> Replace with "physical address range".
> It describes accurately what the function maps.
>
> Signed-off-by: Minu Jin <s9430939@naver.com>

Hm, arguably those are 'kernel' memory in some sense. And 'physical address
range' is a little confusing vs. PFN's as PFN's != physical addresses.

Also remap_pfn_range() is, in effect, a deprecated function as we move drivers
to using mmap_prepare equivalents (implemented in remap_pfn_range_prepare()) so
I'm not sure it's really worth updating?

> ---
>  mm/memory.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index ea6568571131..4e07e03a76a4 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3172,7 +3172,7 @@ static int remap_pfn_range_prepare_vma(struct vm_area_struct *vma,
>  }
>
>  /**
> - * remap_pfn_range - remap kernel memory to userspace
> + * remap_pfn_range - remap physical address range to user space
>   * @vma: user vma to map to
>   * @addr: target page aligned user address to start at
>   * @pfn: page frame number of kernel physical memory address
> --
> 2.43.0
>

Cheers, Lorenzo