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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 E5479C433E0 for ; Thu, 11 Jun 2020 07:27:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1D402074B for ; Thu, 11 Jun 2020 07:27:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TxQNPxCd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726719AbgFKH1g (ORCPT ); Thu, 11 Jun 2020 03:27:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726375AbgFKH1g (ORCPT ); Thu, 11 Jun 2020 03:27:36 -0400 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0E4FC08C5C1 for ; Thu, 11 Jun 2020 00:27:35 -0700 (PDT) Received: by mail-pf1-x444.google.com with SMTP id d66so2299920pfd.6 for ; Thu, 11 Jun 2020 00:27:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=F9YRyl1QH8nNLxQb6YLXx+y0EshlCzJxB+jfKLjlAqM=; b=TxQNPxCdxCFIlxp1IRQ0D8Vg8XFC00Bg44uvyzsUqyx/qoeEbJWb3Mnt5q6gUimqT7 T25vKLwTHkwlPT/ja4Cfdhlny+1HZBqfBwTnX1lgltBfscYNxT8xBAX2YQAgzwhDEa60 GdfWj4jhMDxUKdQMlK62NwFZ0n6OlvWmEkeHonIv3Qq3NZOe2gkw38y8cEhu69qalJjl FGq2+yPg3xe7Wh47U9W/R8HuIlY6E2ELpAezBXHuvX4HVM1Adz+bBpEIBBHizDPmDExV Wi/JAI/TmK9L5DuunYFH56e6fG3wJEPkeC68iUkcKc7s3+m5RCT0RrILg4QdEEysMndO 8qpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=F9YRyl1QH8nNLxQb6YLXx+y0EshlCzJxB+jfKLjlAqM=; b=ZANCzuyWTJX/OtRU/EGJ0WezeiEitajYJFY38IwsgOqvKH3GMGRhwWfG/dJs7MfCSW 4bJKiPLAkD5JKIXWotZCISxkaiJjK25WbPVt1RR1jV6O06WpPhhNLm/2o/zfQLGqxce8 ZIwOTGWnz2hTGpEA2tKL9LEDSW1SiPh1VW+lvQaKojFdXFJDY10oy4g42c+Q9yzPWRwH iANmqHY8ar5SYcJE0qPlUbBalhUQUVSM2GaJJ1HWO/pVFpPiez10jaFvkLZG8dKaHWQV yqK9E9o53TNlvIVWE4kQSf5SxDpxV16HicnLrI1pUUBpk9EURe6wWO0jJfQJitfNkAB4 VzSw== X-Gm-Message-State: AOAM532bz/hSkB14wwOHOJmX7qdapZEoywosOKVhGzpJP177LLMAM7q6 xx2BhhRH3wo5eJ5AUDgOrRo= X-Google-Smtp-Source: ABdhPJwhkrcAHfXYK9Qyr3n+8oV1pTLg7pFg4+NYq8gkVla26gxDRMXpFWipLKzcxbjwfYs46M449A== X-Received: by 2002:a62:5ec2:: with SMTP id s185mr2426106pfb.0.1591860455453; Thu, 11 Jun 2020 00:27:35 -0700 (PDT) Received: from localhost ([2409:10:2e40:5100:6e29:95ff:fe2d:8f34]) by smtp.gmail.com with ESMTPSA id 15sm2152353pfw.189.2020.06.11.00.27.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Jun 2020 00:27:34 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Thu, 11 Jun 2020 16:27:32 +0900 To: Daniel Thompson Cc: Sergey Senozhatsky , Sumit Garg , Petr Mladek , Jason Wessel , Douglas Anderson , kgdb-bugreport@lists.sourceforge.net, Linux Kernel Mailing List , Arnd Bergmann , Andrew Morton , Peter Zijlstra , Steven Rostedt , John Ogness Subject: Re: [PATCH] printk/kdb: Redirect printk messages into kdb in any context Message-ID: <20200611072732.GA429@jagdpanzerIV.localdomain> References: <1589273314-12060-1-git-send-email-sumit.garg@linaro.org> <20200512142533.ta4uejwmq5gchtlx@holly.lan> <20200514084230.GO17734@linux-b0ei> <20200515085021.GS17734@linux-b0ei> <20200515103308.GD42471@jagdpanzerIV.localdomain> <20200515163638.GI42471@jagdpanzerIV.localdomain> <20200610164140.tgzcn5oip2gzgmze@holly.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200610164140.tgzcn5oip2gzgmze@holly.lan> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/06/10 17:41), Daniel Thompson wrote: > > Thanks for the link. I'm slightly surprised it took so many years > > to notice the addition of printk_nmi/printk_safe :) > > Rather by coincidence (at least I think its a coincidence) the problem > has recently become much more obvious. > > 0d00449c7a28 ("x86: Replace ist_enter() with nmi_enter()") just brought > this to the surface by treating debug traps as NMIs. This means the CPU > that takes a breakpoint, and where almost all of the kdb printk() calls > take place, will now unconditionally have printk() interception enabled. Interesting. Feels like ist_enter() should have been using printk_nmi_enter/exit() in the first place. -ss