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Subject: Re: [RFC v11 08/14] mm: page_frag: some minor refactoring before
 adding new API
To: Alexander H Duyck <alexander.duyck@gmail.com>
CC: <davem@davemloft.net>, <kuba@kernel.org>, <pabeni@redhat.com>,
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On 2024/7/30 23:12, Alexander H Duyck wrote:

...

>>         }
>>
>>         nc->pagecnt_bias--;
>>         nc->remaining = remaining - fragsz;
>>
>>         return encoded_page_address(encoded_va) +
>>                 (page_frag_cache_page_size(encoded_va) - remaining);
> 
> Parenthesis here shouldn't be needed, addition and subtractions
> operations can happen in any order with the result coming out the same.

I am playing safe to avoid overflow here, as I am not sure if the allocator
will give us the last page. For example, '0xfffffffffffff000 + 0x1000' will
have a overflow.