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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 048D2C64EBC for ; Wed, 3 Oct 2018 00:15:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96BDF2082A for ; Wed, 3 Oct 2018 00:15:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="TIDPavU2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 96BDF2082A Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726548AbeJCHB0 (ORCPT ); Wed, 3 Oct 2018 03:01:26 -0400 Received: from mail-it1-f172.google.com ([209.85.166.172]:52714 "EHLO mail-it1-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725953AbeJCHB0 (ORCPT ); Wed, 3 Oct 2018 03:01:26 -0400 Received: by mail-it1-f172.google.com with SMTP id 134-v6so6072575itz.2 for ; Tue, 02 Oct 2018 17:15:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=jKZXhPCiJGRHSHVYUXEiAzpUgYvEO41vGGRUtxEQ8KQ=; b=TIDPavU2GEanTlKQcQr39o/pXJJtR6z0R10waFJv4iQTSMHWnj0jGX2xX6JljSB1QQ w3Y66s5wfkzFu4KxqtUBBvuIQ6a9x5x6yIsJyE+nnYx13u/FS2QYwkMhqw87/5WeKzhy LDDSonAnIt0P4mwc5Toa8wyLyFjgN+elN6wA1cqVEXhhyHyR/t17FaiIYFP2mUc63Sod VV+AAK5AC2Ukdvl2cRSpx+oOeGA6hC7xAwgpJFaNlJFPLL/uMzLFCXlozli6P5dxWt50 THw8BgLOrFCyLpXJNm9vIw+UASGw7HSaN2itZCL9QpI3ZFPj81vQ/u1HhoyOlEHwNa7R wZXQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=jKZXhPCiJGRHSHVYUXEiAzpUgYvEO41vGGRUtxEQ8KQ=; b=lP5o141CfPZiLJI/Vah/xaWiIkpSAK+z63srP0m5FSdPg481jrkQhqx9GZ/MW9lOif hS1aApLApk84QroI/z+RGxkDHdl+vG06H3QO3fZNarQw6U7PTwe1Cq0RQvK3NDqqG34z 6iVoGpRBPnXlkAPjgw2tSftNI8Od1YRlM8zQfSsVjebhl8HPRcpX6sp+164idVIEW816 q1Pt03o0NHfzWQx6GNinTMQoXSrJvTW4fRYVv4KWnboN4AQFT3+F8XoEaNEDBRk6N+4F AnajoqauLkhKr/0gqW8cly4tVBWoOdepSyKTtSbfh6CrYjNEpfH8X2Zkkz2jMDhgXpkh 2HGg== X-Gm-Message-State: ABuFfogNJ7cz6Il/L+1QnWXE6Km2FWCvw1fFmL4vDnWc9D7i16E1lMlT 1BZTorV2DjbPbni6VkeInzt7V5k3JeF/SRBZk3ZjUw== X-Google-Smtp-Source: ACcGV63ZA4Y4nizcyZjh0yhLVr3Rv1oNohhG4JWiAbRIlfUU3BnO2VU2SCx/d+v0A479D7MHXIGQHls5Xae1nRfje6U= X-Received: by 2002:a24:2744:: with SMTP id g65-v6mr3979663ita.47.1538525729438; Tue, 02 Oct 2018 17:15:29 -0700 (PDT) MIME-Version: 1.0 References: <20180927194601.207765-1-wonderfly@google.com> <20181001152324.72a20bea@gandalf.local.home> <20181002084225.6z2b74qem3mywukx@pathway.suse.cz> In-Reply-To: <20181002084225.6z2b74qem3mywukx@pathway.suse.cz> From: Daniel Wang Date: Tue, 2 Oct 2018 17:15:17 -0700 Message-ID: Subject: Re: 4.14 backport request for dbdda842fe96f: "printk: Add console owner and waiter logic to load balance console writes" To: Petr Mladek Cc: rostedt@goodmis.org, stable@vger.kernel.org, Alexander.Levin@microsoft.com, akpm@linux-foundation.org, byungchul.park@lge.com, dave.hansen@intel.com, hannes@cmpxchg.org, jack@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mathieu Desnoyers , Mel Gorman , mhocko@kernel.org, pavel@ucw.cz, penguin-kernel@i-love.sakura.ne.jp, peterz@infradead.org, tj@kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, Cong Wang , Peter Feiner Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="0000000000009ab1e5057747efa2" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --0000000000009ab1e5057747efa2 Content-Type: text/plain; charset="UTF-8" On Tue, Oct 2, 2018 at 1:42 AM Petr Mladek wrote: > > Well, I still wonder why it helped and why you do not see it with 4.4. > I have a feeling that the console owner switch helped only by chance. > In fact, you might be affected by a race in > printk_safe_flush_on_panic() that was fixed by the commit: > > 554755be08fba31c7 printk: drop in_nmi check from printk_safe_flush_on_panic() > > The above one commit might be enough. Well, there was one more > NMI-related race that was fixed by: > > ba552399954dde1b printk: Split the code for storing a message into the log buffer > a338f84dc196f44b printk: Create helper function to queue deferred console handling > 03fc7f9c99c1e7ae printk/nmi: Prevent deadlock when accessing the main log buffer in NMI All of these commits already exist in 4.14 stable, since 4.14.68. The deadlock still exists even when built from 4.14.73 (latest tag) though. And cherrypicking dbdda842fe96 fixes it. > > Best Regards, > Petr -- Best, Daniel --0000000000009ab1e5057747efa2 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIIS7QYJKoZIhvcNAQcCoIIS3jCCEtoCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg ghBTMIIEXDCCA0SgAwIBAgIOSBtqDm4P/739RPqw/wcwDQYJKoZIhvcNAQELBQAwZDELMAkGA1UE BhMCQkUxGTAXBgNVBAoTEEdsb2JhbFNpZ24gbnYtc2ExOjA4BgNVBAMTMUdsb2JhbFNpZ24gUGVy c29uYWxTaWduIFBhcnRuZXJzIENBIC0gU0hBMjU2IC0gRzIwHhcNMTYwNjE1MDAwMDAwWhcNMjEw NjE1MDAwMDAwWjBMMQswCQYDVQQGEwJCRTEZMBcGA1UEChMQR2xvYmFsU2lnbiBudi1zYTEiMCAG A1UEAxMZR2xvYmFsU2lnbiBIViBTL01JTUUgQ0EgMTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCC AQoCggEBALR23lKtjlZW/17kthzYcMHHKFgywfc4vLIjfq42NmMWbXkNUabIgS8KX4PnIFsTlD6F GO2fqnsTygvYPFBSMX4OCFtJXoikP2CQlEvO7WooyE94tqmqD+w0YtyP2IB5j4KvOIeNv1Gbnnes 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