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 X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD322C432BE for ; Fri, 20 Aug 2021 04:25:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9386660FBF for ; Fri, 20 Aug 2021 04:25:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232740AbhHTE0A (ORCPT ); Fri, 20 Aug 2021 00:26:00 -0400 Received: from ozlabs.org ([203.11.71.1]:46319 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229457AbhHTEZ6 (ORCPT ); Fri, 20 Aug 2021 00:25:58 -0400 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 4GrT7x1KM1z9sW5; Fri, 20 Aug 2021 14:25:17 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1629433517; bh=TY6nLrmjoHyAzLgmjUDiH3O3rM9kTfEtWkmi+ZvE6rY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=qudDX4J8UWi+6+7ay40xF74TpJv5cn1tKDShtykYbqO0aN8uz7Dk+LBw4Gl6G5AXk /6jCrrW4nVyt2fmGYJy/vu8bu1j1y3yTDdDvMgHc0SDQRiTlnLzeJJ0UBwRIrqIvSU d/EFP6j2FHPpLCx1w5KGwNtKJ7PhGlIJuBMr/u2TdiPESqu76d2WNgpczVCBFFiH/X qidFxO9hZBiSMGIPElyGlVAsc1mtkzp2STrpSIXCawTHn6q4ne1W3x8xXP/sY8FYR1 QBM71FxIuPndLFePXsK3aY761+IdT+UOAW3HRLllVgfahmq5wBwPeAQkmPe7b66adV mJy8XZkR/kZUQ== From: Michael Ellerman To: Daniel Axtens , Lukas Bulwahn , Paul Mackerras , Benjamin Herrenschmidt , Michael Neuling , Anshuman Khandual , kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Lukas Bulwahn , kernel-janitors@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] powerpc: rectify selection to ARCH_ENABLE_SPLIT_PMD_PTLOCK In-Reply-To: <87pmu99e4j.fsf@dja-thinkpad.axtens.net> References: <20210819113954.17515-1-lukas.bulwahn@gmail.com> <20210819113954.17515-3-lukas.bulwahn@gmail.com> <87pmu99e4j.fsf@dja-thinkpad.axtens.net> Date: Fri, 20 Aug 2021 14:25:12 +1000 Message-ID: <87a6lceo9j.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Daniel Axtens writes: > Lukas Bulwahn writes: > >> Commit 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") >> selects the non-existing config ARCH_ENABLE_PMD_SPLIT_PTLOCK in >> ./arch/powerpc/platforms/Kconfig.cputype, but clearly it intends to select >> ARCH_ENABLE_SPLIT_PMD_PTLOCK here (notice the word swapping!), as this >> commit does select that for all other architectures. >> >> Rectify selection to ARCH_ENABLE_SPLIT_PMD_PTLOCK instead. >> > > Yikes, yes, 66f24fa766e3 does seem to have got that wrong. It looks like > that went into 5.13. > > I think we want to specifically target this for stable so that we don't > lose the perfomance and scalability benefits of split pmd ptlocks: > > Cc: stable@vger.kernel.org # v5.13+ > > (I don't think you need to do another revision for this, I think mpe > could add it when merging.) Yeah. I rewrote the change log a bit to make it clear this is a bug fix, not a harmless cleanup. cheers powerpc: Re-enable ARCH_ENABLE_SPLIT_PMD_PTLOCK Commit 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") broke PMD split page table lock for powerpc. It selects the non-existent config ARCH_ENABLE_PMD_SPLIT_PTLOCK in arch/powerpc/platforms/Kconfig.cputype, but clearly intended to select ARCH_ENABLE_SPLIT_PMD_PTLOCK (notice the word swapping!), as that commit did for all other architectures. Fix it by selecting the correct symbol ARCH_ENABLE_SPLIT_PMD_PTLOCK. Fixes: 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") Cc: stable@vger.kernel.org # v5.13+ Signed-off-by: Lukas Bulwahn Reviewed-by: Daniel Axtens [mpe: Reword change log to make it clear this is a bug fix] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210819113954.17515-3-lukas.bulwahn@gmail.com 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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E11F5C4338F for ; Fri, 20 Aug 2021 04:26:06 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 016A660F45 for ; 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dkim-atps=neutral Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (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 4GrT853bvfz2yxF for ; Fri, 20 Aug 2021 14:25:24 +1000 (AEST) 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 4GrT7x1KM1z9sW5; Fri, 20 Aug 2021 14:25:17 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1629433517; bh=TY6nLrmjoHyAzLgmjUDiH3O3rM9kTfEtWkmi+ZvE6rY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=qudDX4J8UWi+6+7ay40xF74TpJv5cn1tKDShtykYbqO0aN8uz7Dk+LBw4Gl6G5AXk /6jCrrW4nVyt2fmGYJy/vu8bu1j1y3yTDdDvMgHc0SDQRiTlnLzeJJ0UBwRIrqIvSU d/EFP6j2FHPpLCx1w5KGwNtKJ7PhGlIJuBMr/u2TdiPESqu76d2WNgpczVCBFFiH/X qidFxO9hZBiSMGIPElyGlVAsc1mtkzp2STrpSIXCawTHn6q4ne1W3x8xXP/sY8FYR1 QBM71FxIuPndLFePXsK3aY761+IdT+UOAW3HRLllVgfahmq5wBwPeAQkmPe7b66adV mJy8XZkR/kZUQ== From: Michael Ellerman To: Daniel Axtens , Lukas Bulwahn , Paul Mackerras , Benjamin Herrenschmidt , Michael Neuling , Anshuman Khandual , kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v2 2/2] powerpc: rectify selection to ARCH_ENABLE_SPLIT_PMD_PTLOCK In-Reply-To: <87pmu99e4j.fsf@dja-thinkpad.axtens.net> References: <20210819113954.17515-1-lukas.bulwahn@gmail.com> <20210819113954.17515-3-lukas.bulwahn@gmail.com> <87pmu99e4j.fsf@dja-thinkpad.axtens.net> Date: Fri, 20 Aug 2021 14:25:12 +1000 Message-ID: <87a6lceo9j.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain 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: Lukas Bulwahn , kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Daniel Axtens writes: > Lukas Bulwahn writes: > >> Commit 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") >> selects the non-existing config ARCH_ENABLE_PMD_SPLIT_PTLOCK in >> ./arch/powerpc/platforms/Kconfig.cputype, but clearly it intends to select >> ARCH_ENABLE_SPLIT_PMD_PTLOCK here (notice the word swapping!), as this >> commit does select that for all other architectures. >> >> Rectify selection to ARCH_ENABLE_SPLIT_PMD_PTLOCK instead. >> > > Yikes, yes, 66f24fa766e3 does seem to have got that wrong. It looks like > that went into 5.13. > > I think we want to specifically target this for stable so that we don't > lose the perfomance and scalability benefits of split pmd ptlocks: > > Cc: stable@vger.kernel.org # v5.13+ > > (I don't think you need to do another revision for this, I think mpe > could add it when merging.) Yeah. I rewrote the change log a bit to make it clear this is a bug fix, not a harmless cleanup. cheers powerpc: Re-enable ARCH_ENABLE_SPLIT_PMD_PTLOCK Commit 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") broke PMD split page table lock for powerpc. It selects the non-existent config ARCH_ENABLE_PMD_SPLIT_PTLOCK in arch/powerpc/platforms/Kconfig.cputype, but clearly intended to select ARCH_ENABLE_SPLIT_PMD_PTLOCK (notice the word swapping!), as that commit did for all other architectures. Fix it by selecting the correct symbol ARCH_ENABLE_SPLIT_PMD_PTLOCK. Fixes: 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") Cc: stable@vger.kernel.org # v5.13+ Signed-off-by: Lukas Bulwahn Reviewed-by: Daniel Axtens [mpe: Reword change log to make it clear this is a bug fix] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210819113954.17515-3-lukas.bulwahn@gmail.com From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Ellerman Date: Fri, 20 Aug 2021 04:25:12 +0000 Subject: Re: [PATCH v2 2/2] powerpc: rectify selection to ARCH_ENABLE_SPLIT_PMD_PTLOCK Message-Id: <87a6lceo9j.fsf@mpe.ellerman.id.au> List-Id: References: <20210819113954.17515-1-lukas.bulwahn@gmail.com> <20210819113954.17515-3-lukas.bulwahn@gmail.com> <87pmu99e4j.fsf@dja-thinkpad.axtens.net> In-Reply-To: <87pmu99e4j.fsf@dja-thinkpad.axtens.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Daniel Axtens , Lukas Bulwahn , Paul Mackerras , Benjamin Herrenschmidt , Michael Neuling , Anshuman Khandual , kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Lukas Bulwahn , kernel-janitors@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org Daniel Axtens writes: > Lukas Bulwahn writes: > >> Commit 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") >> selects the non-existing config ARCH_ENABLE_PMD_SPLIT_PTLOCK in >> ./arch/powerpc/platforms/Kconfig.cputype, but clearly it intends to select >> ARCH_ENABLE_SPLIT_PMD_PTLOCK here (notice the word swapping!), as this >> commit does select that for all other architectures. >> >> Rectify selection to ARCH_ENABLE_SPLIT_PMD_PTLOCK instead. >> > > Yikes, yes, 66f24fa766e3 does seem to have got that wrong. It looks like > that went into 5.13. > > I think we want to specifically target this for stable so that we don't > lose the perfomance and scalability benefits of split pmd ptlocks: > > Cc: stable@vger.kernel.org # v5.13+ > > (I don't think you need to do another revision for this, I think mpe > could add it when merging.) Yeah. I rewrote the change log a bit to make it clear this is a bug fix, not a harmless cleanup. cheers powerpc: Re-enable ARCH_ENABLE_SPLIT_PMD_PTLOCK Commit 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") broke PMD split page table lock for powerpc. It selects the non-existent config ARCH_ENABLE_PMD_SPLIT_PTLOCK in arch/powerpc/platforms/Kconfig.cputype, but clearly intended to select ARCH_ENABLE_SPLIT_PMD_PTLOCK (notice the word swapping!), as that commit did for all other architectures. Fix it by selecting the correct symbol ARCH_ENABLE_SPLIT_PMD_PTLOCK. Fixes: 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") Cc: stable@vger.kernel.org # v5.13+ Signed-off-by: Lukas Bulwahn Reviewed-by: Daniel Axtens [mpe: Reword change log to make it clear this is a bug fix] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210819113954.17515-3-lukas.bulwahn@gmail.com