Re: [PATCH -mm -v4 03/21] mm, THP, swap: Support PMD swap mapping in swap_duplicate()

["Huang\, Ying" <ying.huang@intel.com>]

Dave Hansen <dave.hansen@linux.intel.com> writes:

>> Yes.  Boolean parameter isn't good at most times.  Matthew Wilcox
>> suggested to use
>> 
>>         swap_duplicate(&entry, HPAGE_PMD_NR);
>> 
>> vs.
>> 
>>         swap_duplicate(&entry, 1);
>> 
>> He thinks this makes the interface more flexible to support other swap
>> entry size in the future.  What do you think about that?
>
> That looks great to me too.
>
>>>>  		if (likely(!non_swap_entry(entry))) {
>>>> -			if (swap_duplicate(entry) < 0)
>>>> +			if (swap_duplicate(&entry, false) < 0)
>>>>  				return entry.val;
>>>>  
>>>>  			/* make sure dst_mm is on swapoff's mmlist. */
>>>
>>> I'll also point out that in a multi-hundred-line patch, adding arguments
>>> to a existing function would not be something I'd try to include in the
>>> patch.  I'd break it out separately unless absolutely necessary.
>> 
>> You mean add another patch, which only adds arguments to the function,
>> but not change the body of the function?
>
> Yes.  Or, just add the non-THP-swap version first.

OK, will do this.

Best Regards,
Huang, Ying