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 D2625CD5BDE for ; Wed, 27 May 2026 07:34:36 +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:From:References:Cc:To: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=AWcI+z0XH0AfAPpv/XGcENdcfelIfuJvkL3Jp4qgI2o=; b=An92ajd2XKpDGYy/BLRPmWq9pn sIb0PsY1z3/cDeJnUFFy9DH9GUqV0Oe+kyzMzwgI90cSVQ127RtWOLkjNJeiZNdk6Hg3pk01Os/qL e48J7PyOjgoOZVj3TdB1QeMNxoqmU+yIdJSyO0pN4x0ju5YR9d6OosxV4Y5xK/4A6Ah9dQGdQp3+h O961X3GmcFduJXRC86fGzt4DFjhv9r+zmabyR6kpZ7zWqlZX2yUP1eASw2goNxi/2l8HPx8zdFflR zJ8jo2mdUOvGiD9gBGv34GEL3tyi60yIEDUKH5DbVDKal4kNuxPUdS3OwHaarir1VNrRTs6O2bdmS 5p7KowzA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wS8ma-00000003TLV-3a2H; Wed, 27 May 2026 07:34:28 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wS8mY-00000003TL0-2Q4n for linux-arm-kernel@lists.infradead.org; Wed, 27 May 2026 07:34:27 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BCDA827DC; Wed, 27 May 2026 00:34:19 -0700 (PDT) Received: from [10.57.93.47] (unknown [10.57.93.47]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8928C3F632; Wed, 27 May 2026 00:34:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1779867264; bh=HVqcxI1GFbCS7c35naKWqhplQ5379bUFtfju52VKNUI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lhpGYhy9mzLM0aQ1LmEdrgC7rB9SgaM2E0euQSb2IyT0zWRqzHJdbHCQvPWYTWPEz P7TxGZIzx/4bnsXReJ1v8DM+/x5k4r9aS3DnmQY5y6dTDxqa0kFbXyRop06qe/gjVs u16UwYDXRXQBF7Yv8VbCdByU0IIzdtVpVZ2FuHmg= Message-ID: Date: Wed, 27 May 2026 09:34:19 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arm64: mm: call pagetable dtor when freeing hot-removed page tables To: "David Hildenbrand (Arm)" , Vishal Moola , Catalin Marinas Cc: Andrew Morton , Alistair Popple , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, will@kernel.org References: <20260521032730.2104017-1-apopple@nvidia.com> <20260521153130.d7d5cd060f7522f894252333@linux-foundation.org> <92450154-e1ab-46e4-b23d-eaa59c9cdd3b@arm.com> <1be38262-53de-4a27-9841-393e12fc1475@kernel.org> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <1be38262-53de-4a27-9841-393e12fc1475@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260527_003426_772627_B2BC6A73 X-CRM114-Status: GOOD ( 12.47 ) 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 26/05/2026 14:31, David Hildenbrand (Arm) wrote: > On 5/26/26 13:54, Kevin Brodsky wrote: >> On 22/05/2026 11:36, Vishal Moola wrote: >>>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >>>> index 4c8959153ac4..9d42cbddce27 100644 >>>> --- a/arch/arm64/mm/mmu.c >>>> +++ b/arch/arm64/mm/mmu.c >>>> @@ -1441,6 +1441,9 @@ static void free_hotplug_page_range(struct page *page, size_t size, >>>> >>>> static void free_hotplug_pgtable_page(struct page *page) >>>> { >>>> + if (folio_test_pgtable(page_folio(page))) >>> This should work. >>> >>>> + pagetable_dtor(page_ptdesc(page)); >>>> + >>>> free_hotplug_page_range(page, PAGE_SIZE, NULL); >>> In the case we presumably have a page table page (ptdesc) at this >>> point, we should really be freeing it with pagetable_free() as well. >> Agreed, I think this is the right thing to do, something like: >> >> if (folio_test_pgtable(page_folio(page))) >> pagetable_dtor_free(page_ptdesc(page)); else >> free_hotplug_page_range(page, PAGE_SIZE, NULL); > That code pattern is wrong. > > folio_test_pgtable() shouldn't exist. > > In the future, something is either a pgtable or a folio, not both. > > So check the type against the page, not the folio. In other words use PageTable(page) instead? Interestingly I can see a few calls to folio_test_pgtable() across the kernel but none to PageTable(), maybe just an antipattern then? The ctor/dtor also use __folio_{set,clear}_pgtable(). - Kevin