From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757400AbcCUR2N (ORCPT ); Mon, 21 Mar 2016 13:28:13 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:34903 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757348AbcCUR2H (ORCPT ); Mon, 21 Mar 2016 13:28:07 -0400 From: Sergey Senozhatsky To: Andrew Morton Cc: Jan Kara , Petr Mladek , Tejun Heo , Tetsuo Handa , linux-kernel@vger.kernel.org, Byungchul Park , Sergey Senozhatsky , Sergey Senozhatsky , Jan Kara Subject: [RFC][PATCH v6 2/2] printk: Make wake_up_klogd_work_func() async Date: Tue, 22 Mar 2016 02:25:30 +0900 Message-Id: <1458581130-8677-3-git-send-email-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.8.0.rc3.12.g047057b In-Reply-To: <1458581130-8677-1-git-send-email-sergey.senozhatsky@gmail.com> References: <1458581130-8677-1-git-send-email-sergey.senozhatsky@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jan Kara Offload printing of scheduler deferred messages from IRQ context to a schedulable printing kthread, when possible (the same way we do it in vprintk_emit()). Otherwise, the CPU can spend unbounded amount of time doing printing in console_unlock() from IRQ. Signed-off-by: Jan Kara Signed-off-by: Sergey Senozhatsky --- kernel/printk/printk.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 99c105d6..70cde26 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -349,9 +349,16 @@ static void wake_up_klogd_work_func(struct irq_work *irq_work) int pending = __this_cpu_xchg(printk_pending, 0); if (pending & PRINTK_PENDING_OUTPUT) { - /* If trylock fails, someone else is doing the printing */ - if (console_trylock()) - console_unlock(); + if (!printk_sync && printk_kthread) { + wake_up_process(printk_kthread); + } else { + /* + * If trylock fails, someone else is doing + * the printing + */ + if (console_trylock()) + console_unlock(); + } } if (pending & PRINTK_PENDING_WAKEUP) -- 2.8.0.rc3.12.g047057b