On 10/19/2017 09:03 PM, Michal Hocko wrote:

On Thu 19-10-17 20:26:57, Anshuman Khandual wrote:

quoted

Its already assumed that the PageActive flag is clear on the input
page, hence page_lru(page) will pick the base LRU for the page. In
the same way page_lru(page) will pick active base LRU, once the
flag PageActive is set on the page. This change of LRU list should
happen implicitly through the page flags instead of being hard
coded.

The patch description tells what but it doesn't explain _why_? Does the
resulting code is better, more optimized or is this a pure readability
thing?

Not really. Not only it removes couple of lines of code but it also
makes it look more logical from function flow point of view as well.

All I can see is that page_lru is more complex and a large part of it
can be optimized away which has been done manually here. I suspect the
compiler can deduce the same thing.

Why not ? I mean, that is the essence of the function page_lru() which
should get us the exact LRU list the page should be on and hence we
should not hand craft these manually.

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