linux-kernel - Re: [PATCH v7 4/7] mm,hugetlb: Split prep_new_huge

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Message-ID: <YHZ2xCeo+aVgD28c@localhost.localdomain>
Date:   Wed, 14 Apr 2021 06:59:48 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        David Hildenbrand <david@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        Muchun Song <songmuchun@...edance.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 4/7] mm,hugetlb: Split prep_new_huge_page functionality

On Tue, Apr 13, 2021 at 02:33:41PM -0700, Mike Kravetz wrote:
> > -static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
> > +/*
> > + * Must be called with the hugetlb lock held
> > + */
> > +static void __prep_account_new_huge_page(struct hstate *h, int nid)
> > +{
> > +	h->nr_huge_pages++;
> > +	h->nr_huge_pages_node[nid]++;
> 
> I would prefer if we also move setting the destructor to this routine.
> 	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);

Uhm, but that is the routine that does the accounting, it feels wrong
here, plus...

> 
> That way, PageHuge() will be false until it 'really' is a huge page.
> If not, we could potentially go into that retry loop in
> dissolve_free_huge_page or alloc_and_dissolve_huge_page in patch 5.

...I do not follow here, could you please elaborate some more?
Unless I am missing something, behaviour should not be any different with this
patch.

Thanks


-- 
Oscar Salvador
SUSE L3