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Date: Wed, 5 Nov 2025 15:57:52 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@kernel.org>, Wei Yang
 <richard.weiyang@gmail.com>, Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
 Baolin Wang <baolin.wang@linux.alibaba.com>, "Liam R. Howlett"
 <Liam.Howlett@oracle.com>, 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>, linux-mm@kvack.org,
 linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] mm/huge_memory: fix folio split check for anon folios
 in swapcache.
Message-Id: <20251105155752.fabace52f503424c64517735@linux-foundation.org>
In-Reply-To: <20251105162910.752266-1-ziy@nvidia.com>
References: <20251105162910.752266-1-ziy@nvidia.com>
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On Wed,  5 Nov 2025 11:29:10 -0500 Zi Yan <ziy@nvidia.com> wrote:

> Both uniform and non uniform split check missed the check to prevent
> splitting anon folios in swapcache to non-zero order. Fix the check.

Please describe the possible userspace-visible effects of the bug
especially when proposing a -stable backport.

> Fixes: 58729c04cf10 ("mm/huge_memory: add buddy allocator like (non-uniform) folio_split()")
> Reported-by: "David Hildenbrand (Red Hat)" <david@kernel.org>
> Closes: https://lore.kernel.org/all/dc0ecc2c-4089-484f-917f-920fdca4c898@kernel.org/

I was hopeful, but that's "from code inspection".

> Cc: stable@vger.kernel.org
> Signed-off-by: Zi Yan <ziy@nvidia.com>