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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 20C30C2D0A3 for ; Wed, 4 Nov 2020 00:22:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B0C85223C7 for ; Wed, 4 Nov 2020 00:22:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="MOMRL1jg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729999AbgKDAWB (ORCPT ); Tue, 3 Nov 2020 19:22:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729021AbgKDAUZ (ORCPT ); Tue, 3 Nov 2020 19:20:25 -0500 Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B775DC0613D1; Tue, 3 Nov 2020 16:20:25 -0800 (PST) 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 4CQnNk40jsz9sT6; Wed, 4 Nov 2020 11:20:22 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1604449222; bh=VC+f+ZkJ1S1VxK7q1l35M+IDDfBanUc/kXYdpGzih90=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=MOMRL1jgFBdsMZewwd+uVHelnLRMk+W3GE3jbHfafKAZoB6EK3TxyyP1jzowjSVuC EeLK+n/2Cy4NRCxid55Vrh2Fb8xTZSRrKk4/uBL4akbGdnSvv6ut/ONKxII4lAFtt8 sKwAXlTM4H4Jfrjfa4FUnchZR7YYmwSfh2Oub5A+w29z5LkqZSK5llEWs4U6iccZtJ VKYF1iL66OAK/KKH4CpMGOmy+8ot+QhXzgL6r+LkRduzIMp8/IV5T536jT1yFf8pPN UN2Cp+BxF/UOO5QLR7kzwHNhJSJj5iEemkVNv/i4TfFGd6aTUj580eMaWrphbwWV2N 4cW3d9I6XmPwQ== From: Michael Ellerman To: Greg Kroah-Hartman , linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicholas Piggin , Sasha Levin Subject: Re: [PATCH 4.19 056/191] powerpc: select ARCH_WANT_IRQS_OFF_ACTIVATE_MM In-Reply-To: <20201103203239.940977599@linuxfoundation.org> References: <20201103203232.656475008@linuxfoundation.org> <20201103203239.940977599@linuxfoundation.org> Date: Wed, 04 Nov 2020 11:20:17 +1100 Message-ID: <87361qug5a.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 Greg Kroah-Hartman writes: > From: Nicholas Piggin > > [ Upstream commit 66acd46080bd9e5ad2be4b0eb1d498d5145d058e ] > > powerpc uses IPIs in some situations to switch a kernel thread away > from a lazy tlb mm, which is subject to the TLB flushing race > described in the changelog introducing ARCH_WANT_IRQS_OFF_ACTIVATE_MM. > > Signed-off-by: Nicholas Piggin > Signed-off-by: Michael Ellerman > Link: https://lore.kernel.org/r/20200914045219.3736466-3-npiggin@gmail.com > Signed-off-by: Sasha Levin > --- > arch/powerpc/Kconfig | 1 + > arch/powerpc/include/asm/mmu_context.h | 2 +- > 2 files changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index f38d153d25861..0bc53f0e37c0f 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -152,6 +152,7 @@ config PPC > select ARCH_USE_BUILTIN_BSWAP > select ARCH_USE_CMPXCHG_LOCKREF if PPC64 > select ARCH_WANT_IPC_PARSE_VERSION > + select ARCH_WANT_IRQS_OFF_ACTIVATE_MM This depends on upstream commit: d53c3dfb23c4 ("mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race") Which I don't see in 4.19 stable, or in the email thread here. So this shouldn't be backported to 4.19 unless that commit is also backported. cheers