linux-kernel - Re: [PATCH] mm/nommu: convert kobjsize() to folios

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Message-ID: <23cfeef5-8e3e-4ac9-85e1-03571ec820b5@oracle.com>
Date: Fri, 1 Aug 2025 16:17:45 -0400
From: Sidhartha Kumar <sidhartha.kumar@...cle.com>
To: SeongJae Park <sj@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, willy@...radead.org, vbabka@...e.cz,
        jannh@...gle.com, pfalcato@...e.de, lorenzo.stoakes@...cle.com,
        Liam.Howlett@...cle.com
Subject: Re: [PATCH] mm/nommu: convert kobjsize() to folios

On 8/1/25 3:35 PM, SeongJae Park wrote:
> On Thu, 31 Jul 2025 20:26:29 +0000 Sidhartha Kumar <sidhartha.kumar@...cle.com> wrote:
> 
>> Simple folio conversion to remove a user of PageSlab() and
>> PageCompound().
>>
>> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
> 
> I have a trivial comment below, but since it is just a trivial one that I don't
> really care,
> 
> Reviewed-by: SeongJae Park <sj@...nel.org>
> 

>>   	/*
>> -	 * If it's not a compound page, see if we have a matching VMA
>> +	 * If it's not a compound folio, see if we have a matching VMA
> 
> Nit.  I think "a large folio" rather than "a compound folio" is more consistent
> and easier to read/understand.  No strong opinion, though.

I agree, "large folio" is used throughout the kernel rather than 
compound folio. I'll send a v2 with this change.

Thanks,
Sid

> 
>>   	 * region. This test is intentionally done in reverse order,
>>   	 * so if there's no VMA, we still fall through and hand back
>> -	 * PAGE_SIZE for 0-order pages.
>> +	 * PAGE_SIZE for 0-order folios.
>>   	 */
>> -	if (!PageCompound(page)) {
>> +	if (!folio_test_large(folio)) {
>>   		struct vm_area_struct *vma;
>>   
>>   		vma = find_vma(current->mm, (unsigned long)objp);
>> @@ -100,7 +100,7 @@ unsigned int kobjsize(const void *objp)
>>   	 * The ksize() function is only guaranteed to work for pointers
>>   	 * returned by kmalloc(). So handle arbitrary pointers here.
>>   	 */
>> -	return page_size(page);
>> +	return folio_size(folio);
>>   }
>>   
>>   void vfree(const void *addr)
>> -- 
>> 2.43.0
> 
> 
> Thanks,
> SJ