mm: clean up redundant code

[PATCH v2] mm: clean up redundant code

Posted by Feng Lee 7 months, 1 week ago

Remove pgd_offset_gate() completely and simply make the single
caller use pgd_offset()

It appears that the gate area resides in the kernel-mapped segment
exclusively on IA64. Therefore, removing pgd_offset_k is safe since
IA64 is now obsolete.

Signed-off-by: Feng Lee <379943137@qq.com>

---
Changes in v2:
  - remove pgd_offset_gate completely
  - remove pgd_offset_k from the get_gate_page function completely
---
 include/linux/pgtable.h | 4 ----
 mm/gup.c                | 5 +----
 2 files changed, 1 insertion(+), 8 deletions(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index b50447ef1c92..f1e890b60460 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1164,10 +1164,6 @@ static inline void arch_swap_restore(swp_entry_t entry, struct folio *folio)
 }
 #endif
 
-#ifndef __HAVE_ARCH_PGD_OFFSET_GATE
-#define pgd_offset_gate(mm, addr)	pgd_offset(mm, addr)
-#endif
-
 #ifndef __HAVE_ARCH_MOVE_PTE
 #define move_pte(pte, old_addr, new_addr)	(pte)
 #endif
diff --git a/mm/gup.c b/mm/gup.c
index f32168339390..0685403fe510 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1101,10 +1101,7 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
 	/* user gate pages are read-only */
 	if (gup_flags & FOLL_WRITE)
 		return -EFAULT;
-	if (address > TASK_SIZE)
-		pgd = pgd_offset_k(address);
-	else
-		pgd = pgd_offset_gate(mm, address);
+	pgd = pgd_offset(mm, address);
 	if (pgd_none(*pgd))
 		return -EFAULT;
 	p4d = p4d_offset(pgd, address);
-- 
2.49.0

Re: [PATCH v2] mm: clean up redundant code

Posted by Barry Song 7 months, 1 week ago

On Fri, May 9, 2025 at 1:54 PM Feng Lee <379943137@qq.com> wrote:
>
> Remove pgd_offset_gate() completely and simply make the single
> caller use pgd_offset()

 "."

>
> It appears that the gate area resides in the kernel-mapped segment
> exclusively on IA64. Therefore, removing pgd_offset_k is safe since
> IA64 is now obsolete.
>
> Signed-off-by: Feng Lee <379943137@qq.com>
>

Better to rename the subject to be more specific, e.g.  "mm: remove
obsolete  pgd_offset_gate()" or similar. Otherwise,

Reviewed-by: Barry Song <baohua@kernel.org>

> ---
> Changes in v2:
>   - remove pgd_offset_gate completely
>   - remove pgd_offset_k from the get_gate_page function completely
> ---
>  include/linux/pgtable.h | 4 ----
>  mm/gup.c                | 5 +----
>  2 files changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index b50447ef1c92..f1e890b60460 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -1164,10 +1164,6 @@ static inline void arch_swap_restore(swp_entry_t entry, struct folio *folio)
>  }
>  #endif
>
> -#ifndef __HAVE_ARCH_PGD_OFFSET_GATE
> -#define pgd_offset_gate(mm, addr)      pgd_offset(mm, addr)
> -#endif
> -
>  #ifndef __HAVE_ARCH_MOVE_PTE
>  #define move_pte(pte, old_addr, new_addr)      (pte)
>  #endif
> diff --git a/mm/gup.c b/mm/gup.c
> index f32168339390..0685403fe510 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1101,10 +1101,7 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
>         /* user gate pages are read-only */
>         if (gup_flags & FOLL_WRITE)
>                 return -EFAULT;
> -       if (address > TASK_SIZE)
> -               pgd = pgd_offset_k(address);
> -       else
> -               pgd = pgd_offset_gate(mm, address);
> +       pgd = pgd_offset(mm, address);
>         if (pgd_none(*pgd))
>                 return -EFAULT;
>         p4d = p4d_offset(pgd, address);
> --
> 2.49.0
>

Thanks
barry

Re: [PATCH v2] mm: clean up redundant code

Posted by David Hildenbrand 7 months, 1 week ago

On 09.05.25 04:44, Barry Song wrote:
> On Fri, May 9, 2025 at 1:54 PM Feng Lee <379943137@qq.com> wrote:
>>
>> Remove pgd_offset_gate() completely and simply make the single
>> caller use pgd_offset()
> 
>   "."
> 
>>
>> It appears that the gate area resides in the kernel-mapped segment
>> exclusively on IA64. Therefore, removing pgd_offset_k is safe since
>> IA64 is now obsolete.
>>
>> Signed-off-by: Feng Lee <379943137@qq.com>
>>
> 
> Better to rename the subject to be more specific, e.g.  "mm: remove
> obsolete  pgd_offset_gate()" or similar. Otherwise,

With that

Acked-by: David Hildenbrand <david@redhat.com>

Thanks!

-- 
Cheers,

David / dhildenb