linux-kernel - Re: [PATCH v2 2/5] huge_memory: add huge_zero_page_shrinker

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Message-ID: <fyvz7637sirugvc3yv2qzohpzybgk6zjkuaif4v6k5w5psnckw@3pjssnjpt57p>
Date: Wed, 16 Jul 2025 10:01:24 +0200
From: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
To: David Hildenbrand <david@...hat.com>
Cc: Suren Baghdasaryan <surenb@...gle.com>, 
	Ryan Roberts <ryan.roberts@....com>, Baolin Wang <baolin.wang@...ux.alibaba.com>, 
	Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>, 
	"H . Peter Anvin" <hpa@...or.com>, Vlastimil Babka <vbabka@...e.cz>, Zi Yan <ziy@...dia.com>, 
	Mike Rapoport <rppt@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, 
	Michal Hocko <mhocko@...e.com>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Thomas Gleixner <tglx@...utronix.de>, 
	Nico Pache <npache@...hat.com>, Dev Jain <dev.jain@....com>, 
	"Liam R . Howlett" <Liam.Howlett@...cle.com>, Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org, 
	willy@...radead.org, linux-mm@...ck.org, x86@...nel.org, linux-block@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, "Darrick J . Wong" <djwong@...nel.org>, mcgrof@...nel.org, 
	gost.dev@...sung.com, hch@....de, Pankaj Raghav <p.raghav@...sung.com>
Subject: Re: [PATCH v2 2/5] huge_memory: add
 huge_zero_page_shrinker_(init|exit) function

On Tue, Jul 15, 2025 at 04:18:26PM +0200, David Hildenbrand wrote:
> On 07.07.25 16:23, Pankaj Raghav (Samsung) wrote:
> > From: Pankaj Raghav <p.raghav@...sung.com>
> > 
> > Add huge_zero_page_shrinker_init() and huge_zero_page_shrinker_exit().
> > As shrinker will not be needed when static PMD zero page is enabled,
> > these two functions can be a no-op.
> > 
> > This is a preparation patch for static PMD zero page. No functional
> > changes.
> > 
> > Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> > ---
> >   mm/huge_memory.c | 38 +++++++++++++++++++++++++++-----------
> >   1 file changed, 27 insertions(+), 11 deletions(-)
> > 
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index d3e66136e41a..101b67ab2eb6 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -289,6 +289,24 @@ static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
> >   }
> >   static struct shrinker *huge_zero_page_shrinker;
> > +static int huge_zero_page_shrinker_init(void)
> > +{
> > +	huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero");
> > +	if (!huge_zero_page_shrinker)
> > +		return -ENOMEM;
> > +
> > +	huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count;
> > +	huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan;
> > +	shrinker_register(huge_zero_page_shrinker);
> > +	return 0;
> > +}
> > +
> > +static void huge_zero_page_shrinker_exit(void)
> > +{
> > +	shrinker_free(huge_zero_page_shrinker);
> > +	return;
> > +}
> 
> While at it, we should rename most of that to "huge_zero_folio" I assume.
Sounds good.
> 
> -- 
> Cheers,
> 
> David / dhildenb
>