From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751723AbaCFHVB (ORCPT ); Thu, 6 Mar 2014 02:21:01 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:28361 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751610AbaCFHVA (ORCPT ); Thu, 6 Mar 2014 02:21:00 -0500 Message-ID: <53182182.3080101@huawei.com> Date: Thu, 6 Mar 2014 15:19:30 +0800 From: Liu hua User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: Ingo Molnar CC: , , Li Zefan , Wang Nan , Subject: [PATCH] hung_task : check the value of "sysctl_hung_task_timeout_sec" References: <1394089669-18285-1-git-send-email-sdu.liu@huawei.com> In-Reply-To: <1394089669-18285-1-git-send-email-sdu.liu@huawei.com> X-Forwarded-Message-Id: <1394089669-18285-1-git-send-email-sdu.liu@huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.111.58.238] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As sysctl_hung_task_timeout_sec is unsigned long, when this value is larger then LONG_MAX, the function schedule_timeout_interruptible in watchdog will return immediately without sleep : for example (in x86_64 platform): linux# echo 0xFFFFFFFFFFFFFFFF > /proc/sys/kernel/hung_task_timeout_secs [ 66.798350] schedule_timeout: wrong timeout value ffffffffffffff06 [ 66.800064] schedule_timeout: wrong timeout value ffffffffffffff06 [ 66.801774] schedule_timeout: wrong timeout value ffffffffffffff06 [ 66.803488] schedule_timeout: wrong timeout value ffffffffffffff06 [ 66.805225] schedule_timeout: wrong timeout value ffffffffffffff06 The screen was filled with "schedule_timeout: wrong timeout value ffffffffffffff06" and the system stalled. So I do some check and correction in timeout_jiffies, to let the function schedule_timeout_interruptible allways get the valid parameter. Signed-off-by: Liu Hua --- kernel/hung_task.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 06bb141..ef96650 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -186,7 +186,16 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) static unsigned long timeout_jiffies(unsigned long timeout) { /* timeout of 0 will disable the watchdog */ - return timeout ? timeout * HZ : MAX_SCHEDULE_TIMEOUT; + if ((timeout == 0) || (timeout > MAX_SCHEDULE_TIMEOUT)) { + pr_err("%s : wrong timeout value %lx\n", + __func__, timeout); + pr_err("Timeout value is set to MAX_SCHEDULE_TIMEOUT(%lx) now.\n", + MAX_SCHEDULE_TIMEOUT); + return MAX_SCHEDULE_TIMEOUT; + } + + return (timeout * HZ) < MAX_SCHEDULE_TIMEOUT ? + timeout * HZ : MAX_SCHEDULE_TIMEOUT; } /* -- 1.8.5.5.dirty .