linux-kernel - Re: [PATCH V2] mm/hugetlb: add is_resv_equal

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Message-ID: <YyTmJUsKqAPVk6BH@monkey>
Date:   Fri, 16 Sep 2022 14:09:57 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Xin Hao <xhao@...ux.alibaba.com>, songmuchun@...edance.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] mm/hugetlb: add is_resv_equal_free() func

On 09/16/22 13:12, Andrew Morton wrote:
> On Fri, 16 Sep 2022 14:41:27 +0800 Xin Hao <xhao@...ux.alibaba.com> wrote:
> 
> > In hugetlb.c file, there are several places to compare the values of
> > 'h->free_huge_pages' and 'h->resv_huge_pages', it looks a bit messy, so
> > there add a new is_resv_equal_free() func to do these.
> > 
> > ...
> >
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -1191,6 +1191,11 @@ static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask,
> >  	return NULL;
> >  }
> > 
> > +static inline bool is_resv_equal_free(struct hstate *h)
> 
> I'm not sure that's a well chosen name.  A better name would reflect
> the *meaning* of free_huge_pages being equal to resv_huge_pages.  Maybe
> something like reserves_exhausted()?

How about calling it free_non_reserved_huge_pages() and returning the actual
value (h->free_huge_pages - h->resv_huge_pages)?

Perhaps available_huge_pages()?

It could then be used in at least one other place
- if (h->free_huge_pages - h->resv_huge_pages > 0)

> This would all be clearer if we'd bothered to document the fields of
> struct hstate :(

Agree, and discussed elsewhwere some may even be able to be eliminated.  I can
add that to my todo list.
-- 
Mike Kravetz

> 
> 
> > +{
> > +	return (h->free_huge_pages - h->resv_huge_pages == 0) ? true : false;
> 
> 	return h->free_huge_pages == h->resv_huge_pages;
> 
> > +}
>