From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 47/93] kdb: don't play with console_loglevel Date: Mon, 08 Jun 2020 21:32:19 -0700 Message-ID: <20200609043219.kF0LCzg-q%akpm@linux-foundation.org> References: <20200608212922.5b7fa74ca3f4e2444441b7f9@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:55420 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725770AbgFIEcV (ORCPT ); Tue, 9 Jun 2020 00:32:21 -0400 In-Reply-To: <20200608212922.5b7fa74ca3f4e2444441b7f9@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, daniel.thompson@linaro.org, dianders@chromium.org, dima@arista.com, jason.wessel@windriver.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org From: Dmitry Safonov Subject: kdb: don't play with console_loglevel Print the stack trace with KERN_EMERG - it should be always visible. Playing with console_loglevel is a bad idea as there may be more messages printed than wanted. Also the stack trace might be not printed at all if printk() was deferred and console_loglevel was raised back before the trace got flushed. Unfortunately, after rebasing on commit 2277b492582d ("kdb: Fix stack crawling on 'running' CPUs that aren't the master"), kdb_show_stack() uses now kdb_dump_stack_on_cpu(), which for now won't be converted as it uses dump_stack() instead of show_stack(). Convert for now the branch that uses show_stack() and remove console_loglevel exercise from that case. Link: http://lkml.kernel.org/r/20200418201944.482088-48-dima@arista.com Signed-off-by: Dmitry Safonov Reviewed-by: Douglas Anderson Acked-by: Daniel Thompson Cc: Jason Wessel Signed-off-by: Andrew Morton --- kernel/debug/kdb/kdb_bt.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) --- a/kernel/debug/kdb/kdb_bt.c~kdb-dont-play-with-console_loglevel +++ a/kernel/debug/kdb/kdb_bt.c @@ -21,17 +21,18 @@ static void kdb_show_stack(struct task_struct *p, void *addr) { - int old_lvl = console_loglevel; 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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 E2FA0C433E0 for ; Tue, 9 Jun 2020 04:32:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9F515207F9 for ; Tue, 9 Jun 2020 04:32:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="KvbvDRIj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F515207F9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 43A216B00AC; Tue, 9 Jun 2020 00:32:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3FB1F6B00AE; Tue, 9 Jun 2020 00:32:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2DCE36B00AF; Tue, 9 Jun 2020 00:32:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0180.hostedemail.com [216.40.44.180]) by kanga.kvack.org (Postfix) with ESMTP id 13BB46B00AC for ; Tue, 9 Jun 2020 00:32:22 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id D1EE52495 for ; Tue, 9 Jun 2020 04:32:21 +0000 (UTC) X-FDA: 76908401682.03.horn18_14057d326dbf Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin03.hostedemail.com (Postfix) with ESMTP id A4535140C5 for ; Tue, 9 Jun 2020 04:32:21 +0000 (UTC) X-HE-Tag: horn18_14057d326dbf X-Filterd-Recvd-Size: 3327 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Tue, 9 Jun 2020 04:32:21 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 48E9A20801; Tue, 9 Jun 2020 04:32:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591677140; bh=aO6d2rqJF0BsqL8xyuTvVxcPABXfar8xv/cUN8kdxXk=; h=Date:From:To:Subject:In-Reply-To:From; b=KvbvDRIjall5szohi08tp3ZUXeMhABvfU0M4s9MkJ/FHfH1WJcERzYzGeLlzzkE3t r4K2An2PdcRfOQHXRPFUE6xIhaVK64l89kHgJoaBYFT50YYvKqoveDWzrFgnNzlgVu 866w7uQHO9Fv9cQ0TVSlNm+fz82VuYQQ1asV0JwE= Date: Mon, 08 Jun 2020 21:32:19 -0700 From: Andrew Morton To: akpm@linux-foundation.org, daniel.thompson@linaro.org, dianders@chromium.org, dima@arista.com, jason.wessel@windriver.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 47/93] kdb: don't play with console_loglevel Message-ID: <20200609043219.kF0LCzg-q%akpm@linux-foundation.org> In-Reply-To: <20200608212922.5b7fa74ca3f4e2444441b7f9@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: A4535140C5 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Dmitry Safonov Subject: kdb: don't play with console_loglevel Print the stack trace with KERN_EMERG - it should be always visible. Playing with console_loglevel is a bad idea as there may be more messages printed than wanted. Also the stack trace might be not printed at all if printk() was deferred and console_loglevel was raised back before the trace got flushed. Unfortunately, after rebasing on commit 2277b492582d ("kdb: Fix stack crawling on 'running' CPUs that aren't the master"), kdb_show_stack() uses now kdb_dump_stack_on_cpu(), which for now won't be converted as it uses dump_stack() instead of show_stack(). Convert for now the branch that uses show_stack() and remove console_loglevel exercise from that case. Link: http://lkml.kernel.org/r/20200418201944.482088-48-dima@arista.com Signed-off-by: Dmitry Safonov Reviewed-by: Douglas Anderson Acked-by: Daniel Thompson Cc: Jason Wessel Signed-off-by: Andrew Morton --- kernel/debug/kdb/kdb_bt.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) --- a/kernel/debug/kdb/kdb_bt.c~kdb-dont-play-with-console_loglevel +++ a/kernel/debug/kdb/kdb_bt.c @@ -21,17 +21,18 @@ static void kdb_show_stack(struct task_struct *p, void *addr) { - int old_lvl = console_loglevel; - - console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; kdb_trap_printk++; - if (!addr && kdb_task_has_cpu(p)) + if (!addr && kdb_task_has_cpu(p)) { + int old_lvl = console_loglevel; + + console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; kdb_dump_stack_on_cpu(kdb_process_cpu(p)); - else - show_stack(p, addr); + console_loglevel = old_lvl; + } else { + show_stack_loglvl(p, addr, KERN_EMERG); + } - console_loglevel = old_lvl; kdb_trap_printk--; } _