From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755087AbdC2J24 (ORCPT ); Wed, 29 Mar 2017 05:28:56 -0400 Received: from mail-pg0-f68.google.com ([74.125.83.68]:34715 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754673AbdC2J2y (ORCPT ); Wed, 29 Mar 2017 05:28:54 -0400 From: Sergey Senozhatsky To: Steven Rostedt , Petr Mladek Cc: Jan Kara , Andrew Morton , Linus Torvalds , Peter Zijlstra , "Rafael J . Wysocki" , Eric Biederman , Greg Kroah-Hartman , Jiri Slaby , Pavel Machek , Len Brown , linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [RFC][PATCHv2 0/8] printk: introduce printing kernel thread Date: Wed, 29 Mar 2017 18:25:03 +0900 Message-Id: <20170329092511.3958-1-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.12.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello RFC This patch set adds a printk() kernel thread which lets us to print kernel messages to the console from a non-atomic/schedule-able context, avoiding different sort of lockups, stalls, etc. The biggest difference compared to v1 is a further expansion of "switch to old printk() mode", which we now call printk_emergency mode, annotations (pm, kexec, sysrq). We also have a bunch of other ideas to try out/consider (not in this patch set). E.g. automatic printk_emergency switch on printk_kthread stalls (when we can't run printk_kthread), moving klogd irq_work out of per-CPU memory, and so on. v1->v2: -- introduce printk_emergency mode and API to switch it on/off -- move printk_pending out of per-CPU memory -- add printk emergency_mode sysfs node -- switch sysrq handlers (some of them) to printk_emergency -- cleanus/etc. Sergey Senozhatsky (8): printk: move printk_pending out of per-cpu printk: introduce printing kernel thread printk: offload printing from wake_up_klogd_work_func() pm: switch to printk.emergency mode in unsafe places sysrq: switch to printk.emergency mode in unsafe places kexec: switch to printk.emergency mode in unsafe places printk: add printk emergency_mode parameter printk: enable printk offloading drivers/tty/sysrq.c | 7 ++ include/linux/console.h | 3 + kernel/kexec_core.c | 4 ++ kernel/power/hibernate.c | 8 +++ kernel/power/suspend.c | 4 ++ kernel/printk/printk.c | 178 +++++++++++++++++++++++++++++++++++++++++------ 6 files changed, 182 insertions(+), 22 deletions(-) -- 2.12.2