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From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Muchun Song <songmuchun@bytedance.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: "Oscar Salvador" <osalvador@suse.de>,
	"Dave Hansen" <dave.hansen@intel.com>,
	"Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	"Björn Töpel" <bjorn@rivosinc.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Kevin Brodsky" <kevin.brodsky@arm.com>,
	"Alexander Gordeev" <agordeev@linux.ibm.com>,
	"Alistair Popple" <apopple@nvidia.com>,
	linux-mm@kvack.org, linux-riscv@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	"Muchun Song" <muchun.song@linux.dev>
Subject: Re: [PATCH v2 4/4] arm64/mm: fix destructor for unconstructed hotplug page tables
Date: Mon, 12 Oct 2026 15:30:00 +0200	[thread overview]
Message-ID: <f5dcf4e4-5308-4d1f-946c-2deb4933217d@kernel.org> (raw)
In-Reply-To: <20261010112457.49485-5-songmuchun@bytedance.com>

On 10/10/26 13:24, Muchun Song wrote:
> Commit c594b83457cc ("arm64: mm: call pagetable dtor when freeing
> hot-removed page tables") made free_hotplug_pgtable_page()
> unconditionally run the page-table destructor. This matches page tables
> allocated by the arm64 mapping code, which runs the corresponding
> constructors.
> 
> However, arm64 also uses the generic sparse-vmemmap population code.
> Runtime intermediate page tables allocated by that code do not run a
> page-table constructor. Freeing one during memory hot-remove therefore
> runs a destructor without a matching constructor and corrupts
> NR_PAGETABLE accounting.
> 
> Free intermediate page-table pages through pagetable_free(). It runs the
> destructor only for constructor-backed pages and then releases the page
> through the page-table freeing path.
> 
> Fixes: c594b83457cc ("arm64: mm: call pagetable dtor when freeing hot-removed page tables")
> Cc: stable@vger.kernel.org
> Assisted-by: LLM
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David


WARNING: multiple messages have this Message-ID (diff)
From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Muchun Song <songmuchun@bytedance.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: "Oscar Salvador" <osalvador@suse.de>,
	"Dave Hansen" <dave.hansen@intel.com>,
	"Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	"Björn Töpel" <bjorn@rivosinc.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Kevin Brodsky" <kevin.brodsky@arm.com>,
	"Alexander Gordeev" <agordeev@linux.ibm.com>,
	"Alistair Popple" <apopple@nvidia.com>,
	linux-mm@kvack.org, linux-riscv@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	"Muchun Song" <muchun.song@linux.dev>
Subject: Re: [PATCH v2 4/4] arm64/mm: fix destructor for unconstructed hotplug page tables
Date: Mon, 12 Oct 2026 15:30:00 +0200	[thread overview]
Message-ID: <f5dcf4e4-5308-4d1f-946c-2deb4933217d@kernel.org> (raw)
In-Reply-To: <20261010112457.49485-5-songmuchun@bytedance.com>

On 10/10/26 13:24, Muchun Song wrote:
> Commit c594b83457cc ("arm64: mm: call pagetable dtor when freeing
> hot-removed page tables") made free_hotplug_pgtable_page()
> unconditionally run the page-table destructor. This matches page tables
> allocated by the arm64 mapping code, which runs the corresponding
> constructors.
> 
> However, arm64 also uses the generic sparse-vmemmap population code.
> Runtime intermediate page tables allocated by that code do not run a
> page-table constructor. Freeing one during memory hot-remove therefore
> runs a destructor without a matching constructor and corrupts
> NR_PAGETABLE accounting.
> 
> Free intermediate page-table pages through pagetable_free(). It runs the
> destructor only for constructor-backed pages and then releases the page
> through the page-table freeing path.
> 
> Fixes: c594b83457cc ("arm64: mm: call pagetable dtor when freeing hot-removed page tables")
> Cc: stable@vger.kernel.org
> Assisted-by: LLM
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David

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  reply	other threads:[~2026-10-12 13:30 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-10 11:24 [PATCH v2 0/4] mm: Fix page-table teardown during memory hot-remove Muchun Song
2026-10-10 11:24 ` Muchun Song
2026-10-10 11:24 ` [PATCH v2 1/4] mm: fix missing page-table destructor in pagetable_free() Muchun Song
2026-10-10 11:24   ` Muchun Song
2026-10-12 11:15   ` Jose A. Perez de Azpillaga
2026-10-12 11:15     ` Jose A. Perez de Azpillaga
2026-10-12 12:55     ` Muchun Song
2026-10-12 12:55       ` Muchun Song
2026-10-12 17:21       ` Jose A. Perez de Azpillaga
2026-10-12 17:21         ` Jose A. Perez de Azpillaga
2026-10-13  6:33         ` Muchun Song
2026-10-13  6:33           ` Muchun Song
2026-10-13  2:31       ` Andrew Morton
2026-10-13  2:31         ` Andrew Morton
2026-10-13  2:50         ` Muchun Song
2026-10-13  2:50           ` Muchun Song
2026-10-13  3:25           ` Andrew Morton
2026-10-13  3:25             ` Andrew Morton
2026-10-13  6:26             ` Muchun Song
2026-10-13  6:26               ` Muchun Song
2026-10-12 13:27   ` David Hildenbrand (Arm)
2026-10-12 13:27     ` David Hildenbrand (Arm)
2026-10-12 13:29     ` Muchun Song
2026-10-12 13:29       ` Muchun Song
2026-10-12 14:06   ` Dave Hansen
2026-10-12 14:06     ` Dave Hansen
2026-10-13 15:46   ` Kevin Brodsky
2026-10-13 15:46     ` Kevin Brodsky
2026-10-10 11:24 ` [PATCH v2 2/4] riscv/mm: fix hotplug page-table destructor handling Muchun Song
2026-10-10 11:24   ` Muchun Song
2026-10-12 13:28   ` David Hildenbrand (Arm)
2026-10-12 13:28     ` David Hildenbrand (Arm)
2026-10-12 15:32   ` Björn Töpel
2026-10-12 15:32     ` Björn Töpel
2026-10-13 15:46   ` Kevin Brodsky
2026-10-13 15:46     ` Kevin Brodsky
2026-10-10 11:24 ` [PATCH v2 3/4] riscv/mm: fix missing destructor for hotplug PUD tables Muchun Song
2026-10-10 11:24   ` Muchun Song
2026-10-12 15:35   ` Björn Töpel
2026-10-12 15:35     ` Björn Töpel
2026-10-13 15:46   ` Kevin Brodsky
2026-10-13 15:46     ` Kevin Brodsky
2026-10-10 11:24 ` [PATCH v2 4/4] arm64/mm: fix destructor for unconstructed hotplug page tables Muchun Song
2026-10-10 11:24   ` Muchun Song
2026-10-12 13:30   ` David Hildenbrand (Arm) [this message]
2026-10-12 13:30     ` David Hildenbrand (Arm)
2026-10-13 15:46   ` Kevin Brodsky
2026-10-13 15:46     ` Kevin Brodsky

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