From 48a6d64edadbd40fa5185a890023e9b331d64a48 Mon Sep 17 00:00:00 2001
From: John Siddle <jsiddle@redhat.com>
Date: Tue, 11 Oct 2016 13:55:56 -0700
Subject: [PATCH] hung_task: allow hung_task_panic when hung_task_warnings is 0
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.
[akpm@linux-foundation.org: fix off-by-one]
Link: http://lkml.kernel.org/r/1473450214-4049-1-git-send-email-jsiddle@redhat.com
Signed-off-by: John Siddle <jsiddle@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/hung_task.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 432c3d71d1953..2b59c82cc3e1b 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -98,26 +98,26 @@ 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)
- sysctl_hung_task_warnings--;
-
/*
* 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_all_locks();
+ 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",
+ 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_all_locks();
+ }
touch_nmi_watchdog();
--
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