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 A59DEC55178 for ; Wed, 4 Nov 2020 01:19:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 526052242E for ; Wed, 4 Nov 2020 01:19:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="BvlYY1dd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730474AbgKDBTs (ORCPT ); Tue, 3 Nov 2020 20:19:48 -0500 Received: from bilbo.ozlabs.org ([203.11.71.1]:42465 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729246AbgKDBTs (ORCPT ); Tue, 3 Nov 2020 20:19:48 -0500 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 4CQpjG2wKPz9sTK; Wed, 4 Nov 2020 12:19:46 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1604452786; bh=Pnxsopz9uW6zKe3C5IY9MA7QaAelW0hEbYa9LsvaFoc=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=BvlYY1ddLg/HgYELt5uLxAYE9rqFlO4BWVf1RSRRsdXCPf5PBsrw1XniMtXFxgejg r3urJGMGuOAeP20m+8T6ZvNKu2gvdJ1wXE07xkfWWAVJ5KEzKOOG9Bg4FOxVN5rgPw NA0eo5TlYEl3swtjwD8RsWQ9u3kwep1VXcklwkpqjVtbIfZPltXPwQcBZGpJfyY1oj 6Ll0E/m6o0Vor396c4uS7bK9P74QBfUAsCwR4kuN6gaLLTJ+Jror/l3Fiv8jRLNVfH Me6MSmjU3+gTzjBKe5yvzmBnQdikl7LSKiMj3WysoKn99VoqHkGdkVcKHfF+Vv0Pte soulluRH5vtXA== 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: <87361qug5a.fsf@mpe.ellerman.id.au> References: <20201103203232.656475008@linuxfoundation.org> <20201103203239.940977599@linuxfoundation.org> <87361qug5a.fsf@mpe.ellerman.id.au> Date: Wed, 04 Nov 2020 12:19:45 +1100 Message-ID: <87zh3xude6.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 Michael Ellerman writes: > 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. I just sent you a backport of d53c3dfb23c4 for 4.19. cheers