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Date: Wed, 29 Jul 2026 18:02:41 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: "David Hildenbrand (Arm)" <david@kernel.org>
Cc: xueyuan.chen@vivo.com, Lorenzo Stoakes <ljs@kernel.org>,
 linux-mm@kvack.org, Zi Yan <ziy@nvidia.com>, Baolin Wang
 <baolin.wang@linux.alibaba.com>, "Liam R. Howlett" <liam@infradead.org>,
 Nico Pache <npache@redhat.com>, Ryan Roberts <ryan.roberts@arm.com>, Dev
 Jain <dev.jain@arm.com>, Barry Song <baohua@kernel.org>, Lance Yang
 <lance.yang@linux.dev>, Usama Arif <usama.arif@linux.dev>, Kiryl Shutsemau
 <kas@kernel.org>, Bob Liu <lliubbo@gmail.com>,
 linux-kernel@vger.kernel.org, Xueyuan Chen <xueyuan.chen21@gmail.com>
Subject: Re: [PATCH] mm/huge_memory: fix huge zero folio publication race
Message-Id: <20260729180241.2b8bcb2379b975b22c48d251@linux-foundation.org>
In-Reply-To: <37c40d62-51e2-45b4-9837-a4b96d1640b3@kernel.org>
References: <4ee89c27873fb4d9e598f8a5cfe71d700ecf894e.1785300563.git.xueyuan.chen@vivo.com>
	<37c40d62-51e2-45b4-9837-a4b96d1640b3@kernel.org>
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On Wed, 29 Jul 2026 08:44:12 +0200 "David Hildenbrand (Arm)" <david@kernel.org> wrote:

> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -245,8 +245,11 @@ static bool get_huge_zero_folio(void)
> >  	}
> >  	WRITE_ONCE(huge_zero_pfn, folio_pfn(zero_folio));
> >  
> > -	/* We take additional reference here. It will be put back by shrinker */
> > -	atomic_set(&huge_zero_refcount, 2);
> > +	/*
> > +	 * Publish the folio and PFN before making them available to lockless
> > +	 * users. Pairs with a successful atomic_inc_not_zero() above.
> > +	 */
> > +	atomic_set_release(&huge_zero_refcount, 2);
> >  	preempt_enable();
> >  	count_vm_event(THP_ZERO_PAGE_ALLOC);
> >  	return true;
> 
> https://lore.kernel.org/r/20260728-fix-refcounted-huge-zero-v1-0-3f261f5447b4@kernel.org

Does that actually fix the same thing?

Is so, Xueyuan's Fixes: is 97ae17497e99 ("thp: implement refcounting
for huge zero page").  Which to believe?