* [PATCH] hung_task: Allow hung_task_panic when hung_task_warnings is 0.
@ 2016-09-09 19:43 jsiddle
2016-09-09 20:13 ` Andrew Morton
0 siblings, 1 reply; 3+ messages in thread
From: jsiddle @ 2016-09-09 19:43 UTC (permalink / raw)
To: linux-kernel; +Cc: akpm, penguin-kernel
From: John Siddle <jsiddle@redhat.com>
Previously hung_task_panic would not be respected if enabled after
hung_task_warnings had already been decremented to 0.
Permit the kernel to panic if hung_task_panic is enabled after
hung_task_warnings has already been decremented to 0 and another task
hangs for hung_task_timeout_secs seconds.
Check if hung_task_panic is enabled so we don't return prematurely, and
check if hung_task_warnings is non-zero so we don't print the warning
unnecessarily.
Signed-off-by: John Siddle <jsiddle@redhat.com>
---
kernel/hung_task.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index d234022..938e0a0 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -98,7 +98,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
trace_sched_process_hang(t);
- if (!sysctl_hung_task_warnings)
+ if (!sysctl_hung_task_warnings && !sysctl_hung_task_panic)
return;
if (sysctl_hung_task_warnings > 0)
@@ -108,16 +108,18 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
* Ok, the task did not get scheduled for more than 2 minutes,
* complain:
*/
- pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
- t->comm, t->pid, timeout);
- pr_err(" %s %s %.*s\n",
- print_tainted(), init_utsname()->release,
- (int)strcspn(init_utsname()->version, " "),
- init_utsname()->version);
- pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
- " disables this message.\n");
- sched_show_task(t);
- debug_show_held_locks(t);
+ if (sysctl_hung_task_warnings) {
+ pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
+ t->comm, t->pid, timeout);
+ pr_err(" %s %s %.*s\n",
+ print_tainted(), init_utsname()->release,
+ (int)strcspn(init_utsname()->version, " "),
+ init_utsname()->version);
+ pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
+ " disables this message.\n");
+ sched_show_task(t);
+ debug_show_held_locks(t);
+ }
touch_nmi_watchdog();
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] hung_task: Allow hung_task_panic when hung_task_warnings is 0.
2016-09-09 19:43 [PATCH] hung_task: Allow hung_task_panic when hung_task_warnings is 0 jsiddle
@ 2016-09-09 20:13 ` Andrew Morton
2016-09-10 0:18 ` Tetsuo Handa
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2016-09-09 20:13 UTC (permalink / raw)
To: jsiddle; +Cc: linux-kernel, penguin-kernel
On Fri, 9 Sep 2016 15:43:34 -0400 jsiddle@redhat.com wrote:
> From: John Siddle <jsiddle@redhat.com>
>
> Previously hung_task_panic would not be respected if enabled after
> hung_task_warnings had already been decremented to 0.
>
> Permit the kernel to panic if hung_task_panic is enabled after
> hung_task_warnings has already been decremented to 0 and another task
> hangs for hung_task_timeout_secs seconds.
>
> Check if hung_task_panic is enabled so we don't return prematurely, and
> check if hung_task_warnings is non-zero so we don't print the warning
> unnecessarily.
>
> ...
>
> --- a/kernel/hung_task.c
> +++ b/kernel/hung_task.c
> @@ -98,7 +98,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
>
> trace_sched_process_hang(t);
>
> - if (!sysctl_hung_task_warnings)
> + if (!sysctl_hung_task_warnings && !sysctl_hung_task_panic)
> return;
>
> if (sysctl_hung_task_warnings > 0)
> @@ -108,16 +108,18 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
> * Ok, the task did not get scheduled for more than 2 minutes,
> * complain:
> */
> - pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
> - t->comm, t->pid, timeout);
> - pr_err(" %s %s %.*s\n",
> - print_tainted(), init_utsname()->release,
> - (int)strcspn(init_utsname()->version, " "),
> - init_utsname()->version);
> - pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
> - " disables this message.\n");
> - sched_show_task(t);
> - debug_show_held_locks(t);
> + if (sysctl_hung_task_warnings) {
> + pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
> + t->comm, t->pid, timeout);
> + pr_err(" %s %s %.*s\n",
> + print_tainted(), init_utsname()->release,
> + (int)strcspn(init_utsname()->version, " "),
> + init_utsname()->version);
> + pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
> + " disables this message.\n");
> + sched_show_task(t);
> + debug_show_held_locks(t);
> + }
This introduces an off-by-one error. In the old code, if
sysctl_hung_task_warnings==1 on entry, we warn. With the new code, we
no longer warn.
This?
--- a/kernel/hung_task.c~hung_task-allow-hung_task_panic-when-hung_task_warnings-is-0-fix
+++ a/kernel/hung_task.c
@@ -101,14 +101,12 @@ static void check_hung_task(struct task_
if (!sysctl_hung_task_warnings && !sysctl_hung_task_panic)
return;
- if (sysctl_hung_task_warnings > 0)
- sysctl_hung_task_warnings--;
-
/*
* Ok, the task did not get scheduled for more than 2 minutes,
* complain:
*/
if (sysctl_hung_task_warnings) {
+ sysctl_hung_task_warnings--;
pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
t->comm, t->pid, timeout);
pr_err(" %s %s %.*s\n",
_
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] hung_task: Allow hung_task_panic when hung_task_warnings is 0.
2016-09-09 20:13 ` Andrew Morton
@ 2016-09-10 0:18 ` Tetsuo Handa
0 siblings, 0 replies; 3+ messages in thread
From: Tetsuo Handa @ 2016-09-10 0:18 UTC (permalink / raw)
To: akpm, jsiddle; +Cc: linux-kernel
Andrew Morton wrote:
> This introduces an off-by-one error. In the old code, if
> sysctl_hung_task_warnings==1 on entry, we warn. With the new code, we
> no longer warn.
Since sysctl_hung_task_warnings == -1 is allowed, we should not
sysctl_hung_task_warnings-- unless sysctl_hung_task_warnings > 0.
>
> This?
>
> --- a/kernel/hung_task.c~hung_task-allow-hung_task_panic-when-hung_task_warnings-is-0-fix
> +++ a/kernel/hung_task.c
> @@ -101,14 +101,12 @@ static void check_hung_task(struct task_
> if (!sysctl_hung_task_warnings && !sysctl_hung_task_panic)
> return;
>
> - if (sysctl_hung_task_warnings > 0)
> - sysctl_hung_task_warnings--;
> -
> /*
> * Ok, the task did not get scheduled for more than 2 minutes,
> * complain:
> */
> if (sysctl_hung_task_warnings) {
+ if (sysctl_hung_task_warnings > 0)
> + sysctl_hung_task_warnings--;
> pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
> t->comm, t->pid, timeout);
> pr_err(" %s %s %.*s\n",
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-09-10 0:18 UTC | newest]
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2016-09-09 19:43 [PATCH] hung_task: Allow hung_task_panic when hung_task_warnings is 0 jsiddle
2016-09-09 20:13 ` Andrew Morton
2016-09-10 0:18 ` Tetsuo Handa
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