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Date: Sat, 25 Jan 2014 06:26:01 -0800
From: tip-bot for Aaron Tomlin <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, riel@...hat.com, hpa@...or.com,
mingo@...nel.org, atomlin@...hat.com, tglx@...utronix.de,
rientjes@...gle.com
Subject: [tip:core/urgent] hung_task: Display every hung task warning
Commit-ID: 270750dbc18a71b23d660df110e433ff9616a2d4
Gitweb: http://git.kernel.org/tip/270750dbc18a71b23d660df110e433ff9616a2d4
Author: Aaron Tomlin <atomlin@...hat.com>
AuthorDate: Mon, 20 Jan 2014 17:34:13 +0000
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Sat, 25 Jan 2014 12:13:33 +0100
hung_task: Display every hung task warning
When khungtaskd detects hung tasks, it prints out
backtraces from a number of those tasks.
Limiting the number of backtraces being printed
out can result in the user not seeing the information
necessary to debug the issue. The hung_task_warnings
sysctl controls this feature.
This patch makes it possible for hung_task_warnings
to accept a special value to print an unlimited
number of backtraces when khungtaskd detects hung
tasks.
The special value is -1. To use this value it is
necessary to change types from ulong to int.
Signed-off-by: Aaron Tomlin <atomlin@...hat.com>
Reviewed-by: Rik van Riel <riel@...hat.com>
Acked-by: David Rientjes <rientjes@...gle.com>
Cc: oleg@...hat.com
Link: http://lkml.kernel.org/r/1390239253-24030-3-git-send-email-atomlin@redhat.com
[ Build warning fix. ]
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
Documentation/sysctl/kernel.txt | 42 +++++++++++++++++++++++++++++++++++++++++
include/linux/sched/sysctl.h | 2 +-
kernel/hung_task.c | 6 ++++--
kernel/sysctl.c | 8 +++++---
4 files changed, 52 insertions(+), 6 deletions(-)
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 6d48640..4205f3c 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -33,6 +33,10 @@ show up in /proc/sys/kernel:
- domainname
- hostname
- hotplug
+- hung_task_panic
+- hung_task_check_count
+- hung_task_timeout_secs
+- hung_task_warnings
- kptr_restrict
- kstack_depth_to_print [ X86 only ]
- l2cr [ PPC only ]
@@ -287,6 +291,44 @@ Default value is "/sbin/hotplug".
==============================================================
+hung_task_panic:
+
+Controls the kernel's behavior when a hung task is detected.
+This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
+
+0: continue operation. This is the default behavior.
+
+1: panic immediately.
+
+==============================================================
+
+hung_task_check_count:
+
+The upper bound on the number of tasks that are checked.
+This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
+
+==============================================================
+
+hung_task_timeout_secs:
+
+Check interval. When a task in D state did not get scheduled
+for more than this value report a warning.
+This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
+
+0: means infinite timeout - no checking done.
+
+==============================================================
+
+hung_task_warning:
+
+The maximum number of warnings to report. During a check interval
+When this value is reached, no more the warnings will be reported.
+This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
+
+-1: report an infinite number of warnings.
+
+==============================================================
+
kptr_restrict:
This toggle indicates whether restrictions are placed on
diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 31e0193..3a93f84 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -5,7 +5,7 @@
extern int sysctl_hung_task_check_count;
extern unsigned int sysctl_hung_task_panic;
extern unsigned long sysctl_hung_task_timeout_secs;
-extern unsigned long sysctl_hung_task_warnings;
+extern int sysctl_hung_task_warnings;
extern int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
void __user *buffer,
size_t *lenp, loff_t *ppos);
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 9328b80..0b9c169 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -37,7 +37,7 @@ int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
*/
unsigned long __read_mostly sysctl_hung_task_timeout_secs = CONFIG_DEFAULT_HUNG_TASK_TIMEOUT;
-unsigned long __read_mostly sysctl_hung_task_warnings = 10;
+int __read_mostly sysctl_hung_task_warnings = 10;
static int __read_mostly did_panic;
@@ -98,7 +98,9 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
if (!sysctl_hung_task_warnings)
return;
- sysctl_hung_task_warnings--;
+
+ if (sysctl_hung_task_warnings > 0)
+ sysctl_hung_task_warnings--;
/*
* Ok, the task did not get scheduled for more than 2 minutes,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c398a58..dd5b449 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -122,7 +122,8 @@ extern int blk_iopoll_enabled;
static int sixty = 60;
#endif
-static int neg_one = -1;
+static int __maybe_unused neg_one = -1;
+
static int zero;
static int __maybe_unused one = 1;
static int __maybe_unused two = 2;
@@ -978,9 +979,10 @@ static struct ctl_table kern_table[] = {
{
.procname = "hung_task_warnings",
.data = &sysctl_hung_task_warnings,
- .maxlen = sizeof(unsigned long),
+ .maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_doulongvec_minmax,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &neg_one,
},
#endif
#ifdef CONFIG_COMPAT
--
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