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=-5.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 9CA9CC3F2CE for ; Thu, 5 Mar 2020 01:30:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 722DF20866 for ; Thu, 5 Mar 2020 01:30:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="g06UWHHu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725852AbgCEBaS (ORCPT ); Wed, 4 Mar 2020 20:30:18 -0500 Received: from mail-pl1-f193.google.com ([209.85.214.193]:38178 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725773AbgCEBaR (ORCPT ); Wed, 4 Mar 2020 20:30:17 -0500 Received: by mail-pl1-f193.google.com with SMTP id p7so1889741pli.5 for ; Wed, 04 Mar 2020 17:30:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=bukUsdEeXOt13OEWxPTm2hiZd36XqTTzhqAt335l4G0=; b=g06UWHHudkUqv2Q5AMjN7eznXNf7KlfgLUS9XYjThsRrt2bpLxNqrfuc7CYFTBhld8 A7LvLmR+sDZpyzCLbdj0nuqvGxMr4KfSLG3vBSn7ny5LgcnpJ+gadAYneIYcIq53Pd/M LT+KwJcui2ixJK5WJx3IfpxgjBW7XYeo5twjjR+7yVMfQet3V5KvdTpH8rN5Vo54brMZ dZRLv2b3U9GRVZDgCvKIFjpVdBCWwZ1sJ3vSobLFbkv3XvVF5EfYpu963WtrxxCpufEh XCL32NsKi/KBoSUtLAmcPYMFtzFOj+2jLw45+diZqlA5ldnB2S9jVL6z1sl0zXiQOXyo TPPg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=bukUsdEeXOt13OEWxPTm2hiZd36XqTTzhqAt335l4G0=; b=aFYlE/ADBGV05+hi0+dPALhmnfvw7D7eglslfCUR/JK2lkiIwWQW09lNpS4uZ9b/Ew ALGTEVPeeBPPGzLJfV7znHAPwOT57rU7kecCe0rIb/7/xlKqt+zyaR4vPVQaiJIHK3Iq 2az+HE31ZpZIHSkOx9cidamngHgjh2irNcMTHTIcdc8LjO0mz73Bqg7bT5mjaht5D5SC MaO1yc+LXO94E0v7/bzw+MmisRwp+Xnx16d+ftQa/vMfiHWwfqJQi77LOic3CZWxQD+D 1UI2TbrdyI3yq4lU1Z0buPVVJX0+M8nl5vSpb8lYlnGbYWrSwNH1pGV0gxtedmiTDmpR tNVQ== X-Gm-Message-State: ANhLgQ1NjRLtSNdpnFcexavaYKaNHdAiMzaEGTX8MLLopK38mJFuBMP6 r3NPipXXfeuOUT73byz9h4w= X-Google-Smtp-Source: ADFU+vvYsXGf0bkXDkX5x/pZMUrDxHK7vZ7Xid5HkW+02zq0MKJqpZfm4vxjY2y0saJSucWiww1Rwg== X-Received: by 2002:a17:902:2e:: with SMTP id 43mr5762803pla.326.1583371816977; Wed, 04 Mar 2020 17:30:16 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:5bbb:c872:f2b1:f53b]) by smtp.gmail.com with ESMTPSA id k5sm13521893pfp.67.2020.03.04.17.30.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Mar 2020 17:30:16 -0800 (PST) Date: Thu, 5 Mar 2020 10:30:14 +0900 From: Sergey Senozhatsky To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , linux-kernel@vger.kernel.org, Lech Perczak , Greg Kroah-Hartman , Theodore Ts'o , John Ogness Subject: Re: [PATCHv2] printk: queue wake_up_klogd irq_work only if per-CPU areas are ready Message-ID: <20200305013014.GA174444@google.com> References: <20200303113002.63089-1-sergey.senozhatsky@gmail.com> <20200304152159.2p7d7dnztf433i24@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200304152159.2p7d7dnztf433i24@pathway.suse.cz> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/03/04 16:21), Petr Mladek wrote: [..] > > Fix printk_deferred() and do not queue per-CPU irq_work > > before per-CPU areas are initialized. > > > > [0] https://lore.kernel.org/lkml/aa0732c6-5c4e-8a8b-a1c1-75ebe3dca05b@camlintechnologies.com/ > > > > Signed-off-by: Sergey Senozhatsky > > Reported-by: Lech Perczak > > Cc: Greg Kroah-Hartman > > Cc: Theodore Ts'o > > Cc: John Ogness > > Reviewed-by: Petr Mladek Thanks! > Now, the question is whether to hurry this fix into 5.6 or if > it could wait for 5.7. > > I think that it could wait because 5.6 is not affected by > the particular printk_deferred(). This patch fixes a long-term > generic problem. But I am open for other opinions. Good question. My 5 cents, I would _probably_ push it now. Not because it fixes any known issues on 5.6, but because we have a number of LTS kernel (4.19, 4.14, 4.9, 4.4, 3.16) that can be affected should 1b710b1b10eff9d4 be backported to those kernels. Which is quite likely, I suspect. The sooner we fix printk_deferred(), the sooner -stable/LTS picks up the fix, so that we don't have same regression reports in the future. The regression in question is pretty hard to track down, git-bisect, perhaps, is the only reasonably fast way. -ss