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 A7238C55822 for ; Tue, 4 Aug 2026 13:47:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 812566B00DA; Tue, 4 Aug 2026 09:47:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7EA826B00DC; Tue, 4 Aug 2026 09:47:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 72B336B00DD; Tue, 4 Aug 2026 09:47:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 521966B00DA for ; Tue, 4 Aug 2026 09:47:57 -0400 (EDT) Received: from smtpin04.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 0DD731A0170 for ; Tue, 4 Aug 2026 13:09:27 +0000 (UTC) X-FDA: 85063618374.04.2DFCA57 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf24.hostedemail.com (Postfix) with ESMTP id 5B19818000E for ; Tue, 4 Aug 2026 13:09:25 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Ui7t6UYn; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf24.hostedemail.com: domain of chleroy@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=chleroy@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1785848965; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=4f7ucuIUW8vF4hICwF+LuP1Ke4k5i/LOY8wkqoppgQU=; b=vtpVGGd5xIHEAP3PwCJq5keymW8bAdmJlCU4JvCr9aPBh7110AKmdBo9HgrQkdmciDdiYU DJndBBy+vKgFrEyiE5mT5EDTFKa8us+5lsYhHhr6V5F7nkg4yMcfzwyiY/nCA7yJaVBjeL erSM/g6hCJt+izfBV0S4cVyTLT/OlKo= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Ui7t6UYn; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf24.hostedemail.com: domain of chleroy@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=chleroy@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785848965; b=cSj0JqKT0lhpW1fHK7PFZSdqzBi7/XkpVIUN32icelYCMyktFhgwU+aoWqYF4B+IiZuCAd hxvAnF+eNP95UhBPN6CjEumxcyN6csYeqw/KfriRDlX3c0N0kDavvZcfQ3mFwh12m2VZBF SxkJZVfylGhEel+dFQh/oIbkPPMZdUk= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id C209E60A59; Tue, 4 Aug 2026 13:09:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61BCF1F000E9; Tue, 4 Aug 2026 13:09:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785848964; bh=4f7ucuIUW8vF4hICwF+LuP1Ke4k5i/LOY8wkqoppgQU=; h=Date:From:Subject:To:Cc:References:In-Reply-To; b=Ui7t6UYnjDGA7jUXdMOZJ6Axzrun5isfzKVm2Uxl2vfraDeFP2914FnkkgGhu02mt voOMjZW+YQ46kAl40nY5yZAVMVTwc2qmAKmCz9LQhk5ulRqhzZ/m3BmyZQAM9NVgx8 FwOD9Y8T/fvcC5vlvAad/UEgX4uXdJMGHYQlatXXVZVZd+jSgiNaUDo3eXIDHUpHPb H9f3aviudsPqRTHHXbL4Vk5hI08JKwkf42AE7BMOT0rqjFGPcbbnzBwf1XrdOxPL93 HRXzP9YkSZKmWwWsTd+SDFdFB4YbPaM8pEuJ0zHw4olpd2r+ILT02xSPpdClMWKtk7 45CLGnbTDgBTw== Message-ID: <6bd4f498-6699-4d54-a43a-57c954bff958@kernel.org> Date: Tue, 4 Aug 2026 15:09:13 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: "Christophe Leroy (CS GROUP)" Subject: Re: [PATCH v2 3/6] mm/powerpc/8xx: constify ptep_get() argument To: "Lorenzo Stoakes (ARM)" Cc: Pedro Falcato , David Hildenbrand , Andrew Morton , Catalin Marinas , Will Deacon , "James E.J. Bottomley" , Helge Deller , Madhavan Srinivasan , Michael Ellerman , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kevin Brodsky , Muhammad Usama Anjum , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org References: <20260803164400.531199-1-pfalcato@suse.de> <20260803164400.531199-4-pfalcato@suse.de> Content-Language: fr-FR In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 8a8ad87bixc9td5hat45zie93zrwr9ep X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5B19818000E X-Rspam-User: X-HE-Tag: 1785848965-857781 X-HE-Meta: U2FsdGVkX1+5px5hoWt6PoMD6YlytZvBh/r/kxYX9e6uAGAnyq1NYR0HfmjWknlz2gqYJmGTW3MK0YvZ4wlP4mKV7ir4KXGGYFfNlettufll1jVVk9CcZ7PuOITfcUqJfcqX4oi8fqIaj9RrpTJHtnp+O3qz2A6U7fQtsaoKPXEU0oIj23ewET1EVAf68tzgkTHCk1QLgruveDSJLKCPHvl4qrbzi5f+3A5fdXx4umq4u2pbXZMZtKKX5xM0L+7nhE0xzaxpn4QLSjeyZh2GobO6XlyrS57rHqRSqc/KMHNk3/ZrK7RaiXmKPsFFrZaau0HHi4h96ORL0JInNBM8z+oatIh2ZoByBvp7CXZmsIHbS/bERpFyPdMQweE+WurCzjDtHYGiTI1RyZyDd7W6kWd2Bg90GYSt05wrOHKgj/lliHZdmrp8PXEtrPLdAgVxo+8GyalC5Z5K0Jj+Ie1llMStvyC/6ixN9sPINmofxGIUXSu5tlntsG18XoRtGPMgqfC2gmSLoMCo6lLO8IjRmayC2CjOptdkXGRG1Ilb0s6v2TqkCHV0MnHZ0IMeBhXCluA3TS6weN/jJfnvbbcFjfLvDm9su8SdI5mJemh02Zm3aw9bx3Dc+4phGHFiO7BgQGA0tNIeAPxYYfAuIRqdSWTmnjHAxY/XYySYhzzozWGJbr9ExkBh0QK+/iPkbBIn/LFAWFEgHwd2Na5i7Mpqun68VVcogTuvf8CzGMJCX8Pw1U0xVuf8L98WNsYNyzaRakk/z0LVorx49TBeWFuU4chkvYoAtvDz/QPhjB7OtBkziyRSCq/eeNGszGU74B79sjSXnRaljmf0jZ54b29k0UEnZbV/9XQ8Vaa4dIpqg4zGyHhtO18wFA5Nf0olrWo40HOvEd2KE7AqTi7pnIAgm80sCJwWf4qI/+GQVgcHS37F1qlwa9iihKcnzjAepvzGs8Jj4GTMF1wYqbwpNe/ mERflapX 8WMZv397AdYGdks9SMzAWH+uYqSdnj0480RIPeW7S+Rw427d+meYTZpOWy1JA1GOzgWYF4ddm26mxFiKcw9rTfKhRc6+JDmvCW2TWvLPqI9BfNt4D/aXHKQisVk7VAxf5UBAdLFh+hpvsxZlgwr+Gd+/GkpIPgw+OJBzFYW9m4WZlWTOjyUFHeQnt5uzgb7uUKyJC6EaQHmBiOwi21Y96tM+UpUFFfY4yJWp8ZyfS1wMC0wk9+/XLwL3BiNqFkISMhVY1k1KUB20muHrjFhvQwlNCfjwbJzzcjz/S7/uXF/76GoKQ8gOaSIpQPnpSIdoR11VWxtYFWPWyk53uiKe4RZjyzVOUnh0i2zTASV10qvxdWXUwSJtltpLvNmpAkVhPduJg1DHsqWAybLeu1rcF+wYJKmZzPE4ovjr4onuNFGgLjBc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Le 04/08/2026 à 14:59, Lorenzo Stoakes (ARM) a écrit : > On Tue, Aug 04, 2026 at 02:50:19PM +0200, Christophe Leroy (CS GROUP) wrote: >> Hi Lorenzo, >> >> Le 04/08/2026 à 13:13, Lorenzo Stoakes (ARM) a écrit : >>> On Mon, Aug 03, 2026 at 05:43:57PM +0100, Pedro Falcato wrote: >>>> There is no need for write access to the PTE. >>>> >>>> Signed-off-by: Pedro Falcato >>> >>> With below addressed LGTM so: >>> >>> Reviewed-by: Lorenzo Stoakes (ARM) >>> >>>> --- >>>> arch/powerpc/include/asm/nohash/32/pte-8xx.h | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/arch/powerpc/include/asm/nohash/32/pte-8xx.h b/arch/powerpc/include/asm/nohash/32/pte-8xx.h >>>> index e2ea8ba9f8ca..f2bab31040c7 100644 >>>> --- a/arch/powerpc/include/asm/nohash/32/pte-8xx.h >>>> +++ b/arch/powerpc/include/asm/nohash/32/pte-8xx.h >>>> @@ -226,7 +226,7 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p >>>> >>>> #ifdef CONFIG_PPC_16K_PAGES >>>> #define ptep_get ptep_get >>>> -static inline pte_t ptep_get(pte_t *ptep) >>>> +static inline pte_t ptep_get(const pte_t *ptep) >>>> { >>>> pte_basic_t val = READ_ONCE(ptep->pte); >>>> pte_t pte = {val, val, val, val}; >>> >>> Worth making these const too (that {val, val, val, val} horrifies me btw :)? >> >> Any suggestion welcome. > > I'm being super nitty, all I mean is: > > - pte_basic_t val = READ_ONCE(ptep->pte); > - pte_t pte = {val, val, val, val}; > + const pte_basic_t val = READ_ONCE(ptep->pte); > + const pte_t pte = {val, val, val, val}; > > :) I'm fine with that, I was reacting on the "horrifying". > >> >> powerpc 8xx page table is independant on page size. When you use 16k pages, >> depending on the address you hit the page for the first time, the HW assist >> page table walk will fetch one of four 4k cells in page table that need to >> be identical as they all four define the same 16k page. Not sure I'm clear. > > No that's clear, thanks! > > (I say 'horrifying' because I am looking into RCU page table freeing which this > may complicate, though perhaps not in practice, to be continued :) A few more details here if needed: 55c8fc3f4930 ("powerpc/8xx: reintroduce 16K pages with HW assistance") Christophe