From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4DD84CA9EBB for ; Fri, 9 Oct 2026 20:36:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:References:Cc:To:From:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=qsvSQTb/mkLW7ftqjoW8EveuRC0YRtADluZX056tD6s=; b=wHbKBOMe1y7ubLS04h24piebPE f8kH/EAIxWeAyt2Bf5yt2vwbx50dxcP6IWqSOFeKQAYYw6mKXiXm8sSXxN3J4JRLipWVRv8egDv94 /5ZIHPow6tlUY+01O+iV7opiqXj+BUkTaFEk9wRPGzegMfRexframyY0aN8NxSKgpOxv25XP9xyb5 rdgV5sbiyIK9Cr+te40+WX66ETsvqisrzfKs6mVC8fVPtdfd00Dd2rNccsz1cBCUwMsl0VAGv5ggb UHvC406G9vf3BZTr89xyP5OtS2c/Orl5YGmZ5qsPSU7ffZYaUzvUJB2sUNA/TvF08QWOVbFujCvEF N9IWKb5w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xFHKU-00000007AsM-4BXu; Fri, 09 Oct 2026 20:36:35 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xFHKT-00000007Arz-0eaW; Fri, 09 Oct 2026 20:36:33 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id EFA5D60120; Fri, 9 Oct 2026 20:36:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5E1C1F000FF; Fri, 9 Oct 2026 20:36:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791578191; bh=qsvSQTb/mkLW7ftqjoW8EveuRC0YRtADluZX056tD6s=; h=Date:Subject:From:To:Cc:References:In-Reply-To; b=GLg1cnuJ6do1U7xESKZK430UTlifVgIdS04Wit5vk4OfnCoWthVvEQWbUXYt8mX30 0/IFQUAJXsPkfEYmpvaVVmc07kPx74p5T2FLl26XFDkliiFbqCIdI6Frhu9gN3S5q/ lqswPDyNyFXCYw+5XjMSu4eeohk7I6KZAPNJsVZnTc9fKvCU4ZOQR03N9jY7p8Cu3s QuqPJ0VKJBXqgMvfaaumrRgQIgbFjfBiYdyiKYvH1Hx+iXrWt5Ykyhcd/2pPgyrBJD EN6OBqmIGEix8m1WtBV5guB1BJuQDWtbOW+cnvJpNVemIC52kNxFo4rAONufCe3C+7 UjLoQted9mjXw== Message-ID: <39ae6c48-7fcc-41d5-bfaf-fe626071861e@kernel.org> Date: Fri, 9 Oct 2026 22:36:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] x86/mm: fix missing pgtable destructor for vmemmap tables From: "David Hildenbrand (Arm)" 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> Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 10/9/26 22:33, David Hildenbrand (Arm) wrote: > 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(). Ah, behavior depends on CONFIG_ASYNC_KERNEL_PGTABLE_FREE$ ... Why not do the right thing in pagetable_free() instead? -- Cheers, David