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t=1791578013; bh=aWnreVv1JvFvXL8LlcobuwrybBro3mW0bQFXS2LDkB4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=P9fDb5c8ZUCK3G53nUPYeOnWZCMIcbM8vk2VHvX+l5bTeZrPxUZYFohbmHv1zWTmk rX8S/tqjSEJygh17j0tdYOZL6sixizg8ly6+jfDc30Uei5aM7j/KKapi783xnm8Nyf dfWajST1ImDGiI62Q01/eIjJlTWpkUvQeye8+60Pktoi86SouECmyeL5hDKVb5QMni M/rHUeeuSao6t1O8LZP5dxIhkBc9fDi7ufELFg+EqUJ4BBZqwl/7Du0VnLsI4o/bB+ 3ckEdI09l3Td6rLBM8liiWkSc2kS05mnBiW9shA6tF5qqGJYMGDqXhVwoYRYfOW7+F wDhJVM9gZ+qRg== Message-ID: Date: Fri, 9 Oct 2026 22:33:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] x86/mm: fix missing pgtable destructor for vmemmap tables To: Muchun Song , akpm@linux-foundation.org Cc: linux-mm@kvack.org, stable@vger.kernel.org, osalvador@suse.de, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, linux-riscv@lists.infradead.org, agordeev@linux.ibm.com, kevin.brodsky@arm.com, bjorn@rivosinc.com, apopple@nvidia.com, linux-kernel@vger.kernel.org, muchun.song@linux.dev References: <20261008073021.2512665-1-songmuchun@bytedance.com> <20261008073021.2512665-2-songmuchun@bytedance.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: qi7rfpccrzryyzxcfedbzujjyxrdbyun X-Rspamd-Queue-Id: 6AC0740002 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1791578014-33440 X-HE-Meta: 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 CIuIMoeV 5EzBJzXRA8n1bunIR4Ef0cOX+V/DryBzL/Ia7+ode9jdXGpvWuPVdZoJMGzB+EuUXKHaBXXcXjixxY4bsVhETJj9/osXqqiEs6I+DxQcVuZ+0fIwG0zmkiNzZpfLnrXH63Hx6M5hVQfGTypJOUJz0ZduhOmWeQwGRwK7yPdWV8Q5/x8BZl0H1w8Ij77wkbGc44kg/0ToYfE9yN0OHqbGmSG8g2vs8hl9uz0kNe2KdKC3/QL1f362J/xNI6O4txKt1n1dIZeJscwn5Prilticr0K3uxDXvjAgGajcKIou/BvxuESB+1TLAjuAmDA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/8/26 09:30, Muchun Song wrote: > Since commit 49f599666420 ("mm: call ctor/dtor for kernel PTEs"), > pte_alloc_one_kernel() runs the page-table constructor for kernel PTE > tables. > > HugeTLB vmemmap optimization uses pte_alloc_one_kernel() when splitting > a PMD. Restoring the vmemmap backing pages does not collapse the PTE > table, so a later memory hot-remove eventually frees that table through > free_pagetable(). That path currently calls pagetable_free() directly > without decrementing NR_PAGETABLE. > > Use PageTable() to identify constructor-backed tables and run the > matching destructor before freeing them. Keep reserved and > constructor-free tables on their existing paths. This also prepares > vmemmap teardown for generic runtime allocations through the normal > pgalloc helpers. > > Fixes: 49f599666420 ("mm: call ctor/dtor for kernel PTEs") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Muchun Song > --- > arch/x86/mm/init_64.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 70e682180291..a3ea627157ab 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1003,6 +1003,8 @@ static void __meminit free_pagetable(struct page *page) > { > if (PageReserved(page)) > free_reserved_page(page); > + else if (PageTable(page)) > + pagetable_dtor_free(page_ptdesc(page)); > else > pagetable_free(page_ptdesc(page)); > } pagetable_free() will do ptdesc_test_kernel(pt) -> pagetable_free_kernel(pt) -> pagetable_dtor_free(). IIUC, pte_alloc_one_kernel() will set ptdesc_set_kernel(ptdesc); -- Cheers, David