Re: [PATCH 2/3] mm/rmap: could be partially_mapped only after no entire map

[Wei Yang <richard.weiyang@gmail.com>]

On Sat, Aug 16, 2025 at 08:31:59AM +0200, David Hildenbrand wrote:
>On 15.08.25 12:08, Lorenzo Stoakes wrote:
>> On Fri, Aug 15, 2025 at 08:49:42AM +0000, Wei Yang wrote:
>> > If it is not the last entire map, we are sure the folio is not partially
>> > mapped.
>> > 
>> > Move the check when there is no entire map.
>> > 
>> 
>> This one I don't like, you're having to sit and think about why it is that
>> this would be the case, vs. just unconditionally doing it.
>> 
>> Again, as mentioned on previous series, just because we could do something
>> doesn't mean we should, unless there's statistically reliable perf data on
>> something real-world indicating we _must_, code clarity absolutely beats
>> everything else on importance.
>> 
>> So yeah, sorry but no to this patch, please resend with just the two
>> reviewed (unless David radically disagrees with me :)
>
>The compiler can figure out that "nr == 0" if the "if (last)" branch is not
>taken.
>

Per my understanding, last is a run time value. I don't figure out how
compiler could help here.

I may miss something. Would you mind giving more hint?

>So I tend to prefer keeping it as is.
>-- 
>Cheers
>
>David / dhildenb

-- 
Wei Yang
Help you, Help me