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charset=utf-8 Content-Transfer-Encoding: quoted-printable ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662290674; a=rsa-sha256; cv=none; b=7PxxsPdPc8GHoVSvugpXVXM28QefVeIM++VsA3lFroNecQ1YOFX7I1pFR6/vGs7dB8ITc/ reapiVoee57YxwbvUZJw41zp+K114Vj1zfV/qoYNFcIA+tJH1k020PmmMKIDWj9Z4CEWXs m1aIQ9hlGRgyexI6CxIe/FXtVGfQb2w= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=ellerman.id.au header.s=201909 header.b=pLWU3vik; spf=pass (imf21.hostedemail.com: domain of mpe@ellerman.id.au designates 150.107.74.76 as permitted sender) smtp.mailfrom=mpe@ellerman.id.au; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662290674; 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=SkbbySYMzjN681JuXWKI64my/YXEjiJSMepW8ZINa6s=; b=I5Tf0np2Y1Wgvuf2WB7OuU8m4YTCGKqEoe88hRdlqVaBmWX3CXShYLIWbaNPvZ6QttwTL1 TEsUURMWmO+XmzA+Luf51ovhJl3FJPh4ZzCJV1R2/uaQoPgklRIqgjIofrjE0Hv4KtDQMI +OAxF4/cwmR+ZVX6AbIxoUFe5GsO4kg= Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=ellerman.id.au header.s=201909 header.b=pLWU3vik; spf=pass (imf21.hostedemail.com: domain of mpe@ellerman.id.au designates 150.107.74.76 as permitted sender) smtp.mailfrom=mpe@ellerman.id.au; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: rdmptzeobfnbtwc5ymgmagmjth179t1i X-Rspamd-Queue-Id: 8FA571C006C X-HE-Tag: 1662290673-639023 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000003, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Christophe Leroy writes: > Le 03/09/2022 =C3=A0 14:36, Michael Ellerman a =C3=A9crit=C2=A0: > > ... > >>=20 >> However in commit ba95b5d03596 ("powerpc/mm/book3s/64: Rework page table >> geometry for lower memory usage") the page table layout was reworked to >> shrink the size of the PGD. >>=20 >> As a result the 16GB page size now fits at the PUD level when using 64K >> base page size. >>=20 >> Therefore there are no longer any supported configurations where >> pgd_huge() can be true, so drop the definitions for pgd_huge(), and >> fallback to the generic definition which is always false. > > We also have pgd_huge defined as always false in: > arch/powerpc/include/asm/page.h > arch/powerpc/include/asm/nohash/pgtable.h > > Those could be removed as well as there is a default definition in=20 > include/linux/hugetlb.h =20 Yep. > And then all uses of pgd_huge() in the core mm can be dropped because=20 > powerpc was the only user. The original reason I looked at this is because Mike was looking at things on the mm side and noticed that we were the only user of pgd_huge(). So yeah I think it can be removed from core mm, but I'll leave that up to the mm folks. There are already some other changes in that area in flight that could conflict if I try to do more extensive changes in this series. cheers 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 31B41ECAAD3 for ; Sun, 4 Sep 2022 11:25:13 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4ML8T40yWPz3bVB for ; Sun, 4 Sep 2022 21:25:12 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=pLWU3vik; dkim-atps=neutral Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4ML8SH6bJWz2xJF for ; Sun, 4 Sep 2022 21:24:31 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=pLWU3vik; dkim-atps=neutral Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4ML8SD6XYnz4xD3; Sun, 4 Sep 2022 21:24:28 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1662290669; bh=SkbbySYMzjN681JuXWKI64my/YXEjiJSMepW8ZINa6s=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=pLWU3vikvJcfF6Zr9d88cqXSzuA9+HNfmlheNkAlLN3tzYR2MD2I5LbPXWfJ1GlP3 83o5WLJze5vFcVWcK6brd+2l2mTBUxE2tHJlsnr5M8SQo70Q1oh+cK2wE3dMjmKoo0 Yi04j6y3C1aDDIesv0GWXSe375VUay62WL2iIj0V/nTrTfqgbuOavVz5TGfgR1P7LH qSC2/v4FvctidpicN2Kzt2M/KZOzISMpDjleo+PC75HTs4YjAkbNesuO3VorlxmdXY laAvbcj3wV3mtJ+jmFoNnDzFsmcpyIsaTdPKCxhhk1ew3xMXh/vv7fZrYEp76P4qC7 o+CRFsSyKvoyQ== From: Michael Ellerman To: Christophe Leroy , "linuxppc-dev@lists.ozlabs.org" Subject: Re: [PATCH 1/2] powerpc/mm/64s: Drop pgd_huge() In-Reply-To: <9534a2bd-57d7-400c-500b-4a591dbb3fbc@csgroup.eu> References: <20220903123640.719846-1-mpe@ellerman.id.au> <9534a2bd-57d7-400c-500b-4a591dbb3fbc@csgroup.eu> Date: Sun, 04 Sep 2022 21:24:23 +1000 Message-ID: <87o7vvtmag.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-mm@kvack.org" , "aneesh.kumar@linux.ibm.com" , "mike.kravetz@oracle.com" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Christophe Leroy writes: > Le 03/09/2022 =C3=A0 14:36, Michael Ellerman a =C3=A9crit=C2=A0: > > ... > >>=20 >> However in commit ba95b5d03596 ("powerpc/mm/book3s/64: Rework page table >> geometry for lower memory usage") the page table layout was reworked to >> shrink the size of the PGD. >>=20 >> As a result the 16GB page size now fits at the PUD level when using 64K >> base page size. >>=20 >> Therefore there are no longer any supported configurations where >> pgd_huge() can be true, so drop the definitions for pgd_huge(), and >> fallback to the generic definition which is always false. > > We also have pgd_huge defined as always false in: > arch/powerpc/include/asm/page.h > arch/powerpc/include/asm/nohash/pgtable.h > > Those could be removed as well as there is a default definition in=20 > include/linux/hugetlb.h =20 Yep. > And then all uses of pgd_huge() in the core mm can be dropped because=20 > powerpc was the only user. The original reason I looked at this is because Mike was looking at things on the mm side and noticed that we were the only user of pgd_huge(). So yeah I think it can be removed from core mm, but I'll leave that up to the mm folks. There are already some other changes in that area in flight that could conflict if I try to do more extensive changes in this series. cheers