Re: [PATCH v2 03/20] mm, hugetlb: fix subpool accounting handling

[Joonsoo Kim]

Hello, Aneesh.

First of all, thank you for review!

On Wed, Aug 21, 2013 at 02:58:20PM +0530, Aneesh Kumar K.V wrote:
> Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> writes:
> 
> > If we alloc hugepage with avoid_reserve, we don't dequeue reserved one.
> > So, we should check subpool counter when avoid_reserve.
> > This patch implement it.
> 
> Can you explain this better ? ie, if we don't have a reservation in the
> area chg != 0. So why look at avoid_reserve. 

We don't consider avoid_reserve when chg != 0.
Look at following code.

+       if (chg || avoid_reserve)
+               if (hugepage_subpool_get_pages(spool, 1))

It means that if chg != 0, we skip to check avoid_reserve.

> 
> Also the code will become if you did
> 
> if (!chg && avoid_reserve)
>    chg = 1;
> 
> and then rest of the code will be able to handle the case.


We still pass avoid_reserve to dequeue_huge_page_vma() and check avoid_reserve
there, so maintaining avoid_reserve and checking it separately is better
to understand a logic. And it doesn't matter at all since I eventually unify
these in patch 13.

Thanks.
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