From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68B1448B374; Fri, 9 Oct 2026 20:37:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791578260; cv=none; b=eZPiwyMrETWYn/p1tIy2wRu6raI2V3SIbmT8PuVjMJbOioYYDHh3aj7SKlNtBzT2AxURpBH1AJDlbs9AA6IRXwPUVCGhVZMmeTZOBi+RaYQUZBeZxSZo1dk3jZDadqbu8gr+Wl2+hKngYNpqeipC6ffXxRIA3w1ZF6Y+yucATsE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791578260; c=relaxed/simple; bh=u1rBGcVcuPXbewZ1ga0+eojPnhJhmPgBBl2LcxTCxYs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gjpTmyzARY0++ZOVMM/m4GYil59GcPbPDJKMJsjzbSWBXDFXdO+QPpfAQPDASG08OEuiwm2xZGyzl6Qdqb5fAvmupV2RUP2+YrgpBhRDCiUsK5qRocqz47e/k4Wt6i9XrI98FizqriwCEXW1FJIsHkPW3/SzyC7r2dovq9XxCEI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=O27aeL/A; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="O27aeL/A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 633AF1F0089A; Fri, 9 Oct 2026 20:37:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791578259; bh=f+yeFjVcsD3mWs4RmXLpWFJvwlsWddLCnZ3D+sDgQnM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=O27aeL/A2mRiLDoNKzrDT1uVXrflSw3am10n700SW41y6hC+GG5MGlriX6dfzn4Fg Jxit3FTVr8Kbzew+hraP42StynheUxDySfg0VcS6c/x9S4Jnw9ikSQN2EFh5H5bnlm gkfuB2nvqoUWAHdJyVt+VpKOpbbp7gBoPQMuInJQL6uX8GKE6gWQi1W1cVMdTYsXXQ K+Uhnkf+7Usv1EXOPi9VorJ/tdeAM6XBQbF3PwGnnssjdEj2qevxVa3B9TW1/IyIFR hy7d24L6EKK4M07DeudSftjs+uIqJfswJH8C+bPdy2M49j38/w+Tq33cAlJbq6bTlx Zv3SmbIMSDWgA== Message-ID: <664510b2-3510-499f-aab5-ceddfcc82581@kernel.org> Date: Fri, 9 Oct 2026 22:37:28 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/4] riscv/mm: fix hotplug page-table destructor handling 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> <20261008073021.2512665-3-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 On 10/8/26 09:30, Muchun Song wrote: > RISC-V uses the same memory-hotplug teardown code for the linear map and > vmemmap, although their page-table pages are not always allocated in the > same way. Late linear-map allocations run page-table constructors, while > vmemmap and early allocations may provide constructor-free pages. > > The PTE path unconditionally runs the destructor, which is wrong for > constructor-free vmemmap tables. The PMD path avoids that problem by > using is_vmemmap as a proxy for constructor state, but that assumption > will no longer hold once runtime vmemmap allocations use the normal > pgalloc helpers. > > Page-table constructors record their state in PG_table. Centralize > page-table freeing and use PageTable() to decide whether the destructor > is required. Keep reserved and constructor-free pages on their existing > freeing paths. > > Fixes: c75a74f4ba19 ("riscv: mm: Add memory hotplugging support") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Muchun Song > --- > arch/riscv/mm/init.c | 29 ++++++++++++++--------------- > 1 file changed, 14 insertions(+), 15 deletions(-) > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 857f9a55039c..429a0b015ec1 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -1486,10 +1486,19 @@ struct execmem_info __init *execmem_arch_setup(void) > #endif /* CONFIG_EXECMEM */ > > #ifdef CONFIG_MEMORY_HOTPLUG > +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)); Similar thought, can't we detect that in pagetable_free() somehow and avoid requiring callers to handle that? -- Cheers, David