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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,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 A8F57C432BE for ; Fri, 20 Aug 2021 00:03:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9154860ED3 for ; Fri, 20 Aug 2021 00:03:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237168AbhHTADu (ORCPT ); Thu, 19 Aug 2021 20:03:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236976AbhHTADt (ORCPT ); Thu, 19 Aug 2021 20:03:49 -0400 Received: from mail-pg1-x532.google.com (mail-pg1-x532.google.com [IPv6:2607:f8b0:4864:20::532]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40CA6C061757 for ; Thu, 19 Aug 2021 17:03:12 -0700 (PDT) Received: by mail-pg1-x532.google.com with SMTP id k14so7452384pga.13 for ; Thu, 19 Aug 2021 17:03:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axtens.net; s=google; h=from:to:cc:subject:in-reply-to:references:date:message-id :mime-version; bh=vRFO+rG5NKULoNq4nrGremPyKJ3sp4O0aBsDwvD+Jws=; b=bUVS0z1tbTEuTnJpUI0DCsREOWqYBS393adFo6vkPpAcDd3VFldkcu6Bu8+NPNkVIr zVB/aqzwm03BccvSPAo1MxAZoGqM1V3G7Ml6IdOp9vADp+ZnRlfr9+qSxRd7e6+I4Agi 5JhMzvnd1IByLpNrXS8swwAmSNZRyvnAn463M= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=vRFO+rG5NKULoNq4nrGremPyKJ3sp4O0aBsDwvD+Jws=; b=sKw66jzlqLgeI/j5gsMBht49FTHh0y+7M0kL5NnCwxDAjrXxuSahYliAgineSDKlW2 WWy9LFdNqZa2K7Zv25/oJkrfLR723XPh62PLkCMyUkWvWk2DONy82hB06O++TG7Uak79 ZQSQWnZKtl/J0X257VNXovcrtieVzyMqDaGIgnCyHfEtN12YkR1O9Waxn/htb9gK318P KGFdj7W1n6J7xSI9snvpb65rsD513Adco3RV6EonnwuUgY80lJldm2ZoOR7nOUe8hWPy kOftDDcWDXpRz6Eu30/E+STUBIEktmHNX9Az6DHgQkxgpfmVK8gd3sLsDzN4xN8SQ8IY 6C7g== X-Gm-Message-State: AOAM531oEGnFDIKBF1s2qsAUz8XG5GwLKO+yG8cFQZRzAeEOMR1QxMdv WZP0B6xI69RawyismFvvyjw66w== X-Google-Smtp-Source: ABdhPJxUAM4AJRANovdfNIBfj6aTNBPXbXy30qW0KYGlBj+lnS2H5nQpOUOt6OPGf27oUrWy+/Ipjg== X-Received: by 2002:a63:2242:: with SMTP id t2mr15735424pgm.111.1629417791779; Thu, 19 Aug 2021 17:03:11 -0700 (PDT) Received: from localhost ([2001:4479:e000:e400:3a83:f47e:d5a3:378a]) by smtp.gmail.com with ESMTPSA id d15sm3189825pfh.34.2021.08.19.17.03.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Aug 2021 17:03:11 -0700 (PDT) From: Daniel Axtens To: Lukas Bulwahn , Paul Mackerras , Michael Ellerman , 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: <20210819113954.17515-3-lukas.bulwahn@gmail.com> References: <20210819113954.17515-1-lukas.bulwahn@gmail.com> <20210819113954.17515-3-lukas.bulwahn@gmail.com> Date: Fri, 20 Aug 2021 10:03:08 +1000 Message-ID: <87pmu99e4j.fsf@dja-thinkpad.axtens.net> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.) I tried to check whether we accidentally broke SPLIT_PMD_PTLOCKs while they were disabled: - There hasn't been any change to the pgtable_pmd_page_ctor or _dtor prototypes, and we haven't made any relevant changes to any of the files in arch/powerpc that called it. - I checked out v5.13 and powerpc/merge, applied this patch, built a pseries_le_defconfig and boot tested it in qemu. It didn't crash on boot or with /bin/sh and some shell commands, but I didn't exactly stress test the VM subsystem either. This gives me some confidence it's both good for powerpc and stable-worthy. Overall: Reviewed-by: Daniel Axtens Kind regards, Daniel > Fixes: 66f24fa766e3 ("mm: drop redundant ARCH_ENABLE_SPLIT_PMD_PTLOCK") > Signed-off-by: Lukas Bulwahn > --- > arch/powerpc/platforms/Kconfig.cputype | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype > index 6794145603de..a208997ade88 100644 > --- a/arch/powerpc/platforms/Kconfig.cputype > +++ b/arch/powerpc/platforms/Kconfig.cputype > @@ -98,7 +98,7 @@ config PPC_BOOK3S_64 > select PPC_HAVE_PMU_SUPPORT > select HAVE_ARCH_TRANSPARENT_HUGEPAGE > select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION > - select ARCH_ENABLE_PMD_SPLIT_PTLOCK > + select ARCH_ENABLE_SPLIT_PMD_PTLOCK > select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE > select ARCH_SUPPORTS_HUGETLBFS > select ARCH_SUPPORTS_NUMA_BALANCING > -- > 2.26.2