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 C0F74C0015E for ; Sat, 5 Aug 2023 12:42:25 +0000 (UTC) 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=pz2IPiZI; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4RJ2KW63lkz3cV4 for ; Sat, 5 Aug 2023 22:42:23 +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=pz2IPiZI; dkim-atps=neutral Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4RJ2JQ5nw2z2yV3 for ; Sat, 5 Aug 2023 22:41:26 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1691239286; bh=U7xpB8WP9+c+u0pETmyJj6pivsKVWoPB3NMLS1v07KM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=pz2IPiZI5tkIO4C9Az380sa4qaqxLBHJHfOtAYQ6ANM86aEMLMqVUWxTGCC4RZQqW zU4BZ8anjDIGrb0dHAU2i4nf4B1NzMn1G48UkMFWmwzumqBPwxUlU/Vp5PpFzSAuoB PrTn5iAqixO3nsXQ74SrFsc26peUhF2gFcCM7KUB5Sj9WTVmev7UxJEBEr6bpIZZPe En3P2DpCj0tmc2btK72pALbRr0QN0jd/DAJ9YxWFrxfHZ9A6WMW9n/xRF1xIL0Pa8B 0WPWj2KjCDO9w/d/WwrcPVpT6vOvRbJxRDVP1W6SEz87xBKzbpgOwDdkqZYXmbj2kQ SaaIkKhDbPB/w== 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 X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4RJ2JQ2TF7z4wqW; Sat, 5 Aug 2023 22:41:25 +1000 (AEST) From: Michael Ellerman To: Christophe Leroy , "linuxppc-dev@lists.ozlabs.org" Subject: Re: [PATCH] powerpc/mm: Reinstate ARCH_FORCE_MAX_ORDER ranges In-Reply-To: <8011d806-5b30-bf26-2bfe-a08c39d57e20@csgroup.eu> References: <20230519113806.370635-1-mpe@ellerman.id.au> <8011d806-5b30-bf26-2bfe-a08c39d57e20@csgroup.eu> Date: Sat, 05 Aug 2023 22:41:24 +1000 Message-ID: <87v8dt4q6j.fsf@mail.lhotse> 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" , "akpm@linux-foundation.org" , "rppt@kernel.org" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Christophe Leroy writes: > Le 19/05/2023 =C3=A0 13:38, Michael Ellerman a =C3=A9crit=C2=A0: >> Commit 1e8fed873e74 ("powerpc: drop ranges for definition of >> ARCH_FORCE_MAX_ORDER") removed the limits on the possible values for >> ARCH_FORCE_MAX_ORDER. >> >> However removing the ranges entirely causes some common work flows to >> break. For example building a defconfig (which uses 64K pages), changing >> the page size to 4K, and rebuilding used to work, because >> ARCH_FORCE_MAX_ORDER would be clamped to 12 by the ranges. >> >> With the ranges removed it creates a kernel that builds but crashes at >> boot: >> kernel BUG at mm/huge_memory.c:470! >> Oops: Exception in kernel mode, sig: 5 [#1] >> ... >> NIP hugepage_init+0x9c/0x278 >> LR do_one_initcall+0x80/0x320 >> Call Trace: >> do_one_initcall+0x80/0x320 >> kernel_init_freeable+0x304/0x3ac >> kernel_init+0x30/0x1a0 >> ret_from_kernel_user_thread+0x14/0x1c >> >> The reasoning for removing the ranges was that some of the values were >> too large. So take that into account and limit the maximums to 10 which >> is the default max, except for the 4K case which uses 12. > > There is something wrong: > > ~# echo 1 > /sys/kernel/mm/hugepages/hugepages-8192kB/nr_hugepages > sh: write error: Invalid argument > > $ grep -e MAX_ORDER -e K_PAGES .config > CONFIG_PPC_4K_PAGES=3Dy > # CONFIG_PPC_16K_PAGES is not set > CONFIG_ARCH_FORCE_MAX_ORDER=3D10 That's 32-bit I guess? So you're hitting the default case, ie. range 10 10. I see we have: arch/powerpc/configs/fsl-emb-nonhw.config:CONFIG_ARCH_FORCE_MAX_ORDER=3D12 And that config fragment is included by: mpc85xx_defconfig mpc85xx_smp_defconfig corenet32_smp_defconfig corenet64_smp_defconfig mpc86xx_defconfig mpc86xx_smp_defconfig So for a lot of platforms the "default" was actually 12 in the past, despite what it says in Kconfig. > In the past MAX_ORDER used to be 12 but now it is force to 10. This should fix it? cheers diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 0b1172cbeccb..b3fdb3d26836 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -917,7 +917,7 @@ config ARCH_FORCE_MAX_ORDER default "6" if PPC32 && PPC_64K_PAGES range 4 10 if PPC32 && PPC_256K_PAGES default "4" if PPC32 && PPC_256K_PAGES - range 10 10 + range 10 12 default "10" help The kernel page allocator limits the size of maximal physically