linux-kernel - Re: [PATCH v2] mm: clean up redundant code

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Message-ID: <tencent_40ADC102E7DD9065891B95206EF54025F10A@qq.com>
Date: Fri,  9 May 2025 11:06:34 +0800
From: Feng Lee <379943137@...com>
To: 21cnbao@...il.com
Cc: 379943137@...com,
	akpm@...ux-foundation.org,
	anshuman.khandual@....com,
	david@...hat.com,
	jgg@...pe.ca,
	jhubbard@...dia.com,
	lance.yang@...ux.dev,
	linux-kernel@...r.kernel.org,
	maobibo@...ngson.cn,
	mingo@...nel.org,
	peterx@...hat.com,
	trivial@...nel.org
Subject: Re: [PATCH v2] mm: clean up redundant code

>On Fri, May 9, 2025 at 1:54 PM Feng Lee <379943137@...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@...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@...nel.org>

Thank you very much for your review comments. I will promptly implement 
the suggested revisions.

>> ---
>> 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

Best regards,
Feng