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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6F06CCD6E41 for ; Wed, 27 May 2026 09:30:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AFB526B0005; Wed, 27 May 2026 05:30:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AACC56B008A; Wed, 27 May 2026 05:30:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 998AA6B008C; Wed, 27 May 2026 05:30:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 85F9E6B0005 for ; Wed, 27 May 2026 05:30:50 -0400 (EDT) Received: from smtpin29.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id BF170161920 for ; Wed, 27 May 2026 09:30:49 +0000 (UTC) X-FDA: 84812680218.29.C75404B Received: from mail-wm1-f53.google.com (mail-wm1-f53.google.com [209.85.128.53]) by imf31.hostedemail.com (Postfix) with ESMTP id D994F20004 for ; Wed, 27 May 2026 09:30:47 +0000 (UTC) Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=iAn2tyN3; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf31.hostedemail.com: domain of vishal.moola@gmail.com designates 209.85.128.53 as permitted sender) smtp.mailfrom=vishal.moola@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1779874248; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=UeNp5zNgXhh9w9gen/mqg7KXpKPshnm2ZyOIypYk7Gw=; b=eYmGi/NCHT3hxydivij5U8MlGnYCg7DYwOtvPseCefqHa/FoOM2U1I8E8kkaeF9eN3dL9o 2HrRfZm6gsoYTFrrXJOMzlIs/8TVTFJGlBgTX0ah/l4W/CBsNJtVoXLWauuFOa+b0EESwR zYyGfcpipL29r3BZz++uZyPJnG+cIYw= ARC-Authentication-Results: i=1; imf31.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=iAn2tyN3; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf31.hostedemail.com: domain of vishal.moola@gmail.com designates 209.85.128.53 as permitted sender) smtp.mailfrom=vishal.moola@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779874248; a=rsa-sha256; cv=none; b=aTbbe7mX0pvyje9D7yXD8mT0Vuf46cLUdnesW1Zs5wMawRZ7KN9keEnzw9xZnwo0zcJoY8 otDzhVxQvc49gAawpF20+ttrpObO+qTY11PJjMbRGxFlyDad22TVROtPjOvFoFuWF9Rkw3 /c72121Qkisf3D5Vb0xf7ipXpr9ywmo= Received: by mail-wm1-f53.google.com with SMTP id 5b1f17b1804b1-49050bfe053so19041715e9.3 for ; Wed, 27 May 2026 02:30:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779874246; x=1780479046; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=UeNp5zNgXhh9w9gen/mqg7KXpKPshnm2ZyOIypYk7Gw=; b=iAn2tyN3jzT+xdlmXoEw6sRsPQwP1s5awaO4U1GQYUFfOBqhQPwdURkQ6b5m1i+UvP 9rEToT0kT3hmtirVOewbTYWVFZFqnrt8i7RUhgqNFZuhiVQwIyd+CxCF0wHvbFvpKC11 xBfIjTsVqx+Gm2C/0KuDJI9GhUO4BFO0wh4WvTnb4FfpaI4U254rr+41HQ6iYdFfv9ez cK30WqZWF544tdwrwWq8cjkgrh9QZAvSYlsnGcBDnrlAp4FTmHieUErzq+1Oh+kZEo1S XmwAcHZ7gj9EMLZwU1ypazbbhIABeZ9cysAs/zGDxS7LgZXiUucuHtBQ3zsEkNy8PndW YHyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779874246; x=1780479046; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=UeNp5zNgXhh9w9gen/mqg7KXpKPshnm2ZyOIypYk7Gw=; b=PJVJLcpnvgGfaUCkhjzHIalzh5fJEUq2XiLyhA76S+QMxc4IbwgdYDUM1xbk4V5Eev 1U0yWWBWw6M0z1lqhMuKt+oDOiChRvFrlI/O/zUjB19rgoLxZ9XfK8afpQxOfejHqDpv iHPPtt9BkPPaqXLqaPW+4bkPUiGxQ1hAbYe16FRg70b4DOxdjZdZ/Cmfg9madum9ha7h PHK/3R1woqGc4KBy1cywDj5m9F8e3in8CB8RfywxjYyJ1VCJBw8KxQdKgA8dTRTOU+jM tPk+M2qj4xxBxVCIdHhu8sMelos4OKeTCtUt+LdVDgcjmW2HdNeSRY5JgGbERPlqPOGj 61SA== X-Forwarded-Encrypted: i=1; AFNElJ+ujg7Dlk+hos5XUhDwo2E6rSvT0rePMlbs0s0Q00EItQePrXyURj6/+xttqmtbAh2y0CSo7k7aMg==@kvack.org X-Gm-Message-State: AOJu0Yw0KBszP5hLEAthXCz+8ona7VdK/R9bO8JmSg9SxoYXRpwtYef+ JCX+xEJf1NaGkk5qjjYbpokr2T0uxn0X4OxP2k0z2LNybWS8DHMPqINw X-Gm-Gg: Acq92OGJO809j1wzId+HeGdfaPUT1VKNn5FAQHrFLVxZtwCItnkfunmP5h40kMHksDg WYGVhVr8bQr3Pjt0IvqMrPvVb9RN34zNiboShsF2p/y7chkfcNBiIT1Vy7r9K3jApdRTNLPEbye boRV7TA/eGtPSCrhQctF6LrAsC2ffvwYpcQTperpykwR1hrRFLtdkSBvF+Fs37gzFwCrVBbLvlf CQJAFlRxJ/wr8bx9zrW9QXM5jrnGAL1ZDKUppyx16nv8YQORvrBnK3Y+Zo5bT3eqrPSB5scOKhH KgNq0ZrAV1KVDGt+7dEDp5XCU+CKpYOM9XCsfOVCvzdyW3q3p2WiPk4ZXcbpUmviWHDY2tm6e64 XT+dObYg0q9/squ493QO6s7HSQgZigJGvJGtmxbIHJrOchiEyvXXs4nk9t9+f1rqS+wmkTcv0IX 5karDXGAIhnNByN1fplkBzDlLzwTj1DVJAgs3449YlBccV9EOVVNc1ejZqctl1PnrfY0JJFWWIu qz74VXt6VEMHARjsynANPL+u6Ry/FXu2A== X-Received: by 2002:a05:600c:8b23:b0:48f:d5b2:7c1a with SMTP id 5b1f17b1804b1-490425aa7a4mr390195565e9.13.1779874246051; Wed, 27 May 2026 02:30:46 -0700 (PDT) Received: from fedora (cpc92878-cmbg18-2-0-cust539.5-4.cable.virginm.net. [86.16.54.28]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49045282201sm427410665e9.8.2026.05.27.02.30.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2026 02:30:45 -0700 (PDT) Date: Wed, 27 May 2026 10:30:43 +0100 From: Vishal Moola To: Kevin Brodsky Cc: Will Deacon , Catalin Marinas , Andrew Morton , Alistair Popple , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org Subject: Re: [PATCH] arm64: mm: call pagetable dtor when freeing hot-removed page tables Message-ID: References: <20260521032730.2104017-1-apopple@nvidia.com> <20260521153130.d7d5cd060f7522f894252333@linux-foundation.org> <92450154-e1ab-46e4-b23d-eaa59c9cdd3b@arm.com> <423a2656-e1a3-473e-abeb-5e301c6f7c2a@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <423a2656-e1a3-473e-abeb-5e301c6f7c2a@arm.com> X-Stat-Signature: eg91n6aa4k195jzsocanj6758xxnqr3k X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D994F20004 X-Rspam-User: X-HE-Tag: 1779874247-266696 X-HE-Meta: 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 jOM4eXaB 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, May 27, 2026 at 09:35:50AM +0200, Kevin Brodsky wrote: > On 26/05/2026 17:07, Will Deacon wrote: > > On Tue, May 26, 2026 at 01:54:00PM +0200, 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); > >> > >> > >> Strangely enough x86 calls pagetable_free() in both cases. > >> > >> My series protecting page tables with pkeys has a patch [1] to get > >> vmemmap to allocate page tables with pagetable_alloc(). The diff above > >> will require pagetable_*_ctor() to be called as well, but I think that's > >> the right thing to do anyway. That could be posted as a separate series, > >> but I'm hesitant due to the lack of NUMA awareness in pagetable_alloc(). > > I agree that calling the ctor()/dtor() functions consistently is the > > cleanest approach and that will need something like your patch to call > > the constructor from vmemmap_alloc_block_zero(). Trying to elide these > > calls for the page-table pages used to map the altmap just feels odd to > > me, as there isn't anything particularly special about them afaik. > > I don't think they're really special either, most likely they just got > missed/ignored for the purpose of ctor/dtor like many other kernel page > tables (until recently). > > I'll prepare a series refactoring that code then - that will also > require changing most arch implementations of vmemmap_free() to call > pagetable_dtor_free(). Take a look at Matthew's series[1]. I think thats the ideal approach for page table accounting. He hasn't had time to iterate on it though. I doubt he'd mind if someone picked it up. > In the meantime we should probably use the logic above to avoid the BUG > that Alistair reported. Agreed. [1] https://lore.kernel.org/linux-mm/20251113140448.1814860-4-willy@infradead.org/