The hung_task_panic sysctl is currently a blunt instrument: it's all or
nothing.
Panicking on a single hung task can be an overreaction to a transient
glitch. A more reliable indicator of a systemic problem is when
multiple tasks hang simultaneously.
Extend hung_task_panic to accept an integer threshold, allowing the
kernel to panic only when N hung tasks are detected in a single scan.
This provides finer control to distinguish between isolated incidents
and system-wide failures.
The accepted values are:
- 0: Don't panic (unchanged)
- 1: Panic on the first hung task (unchanged)
- N > 1: Panic after N hung tasks are detected in a single scan
The original behavior is preserved for values 0 and 1, maintaining full
backward compatibility.
[lance.yang@linux.dev: new changelog]
Link: https://lkml.kernel.org/r/20251015063615.2632-1-lirongqing@baidu.com
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Tested-by: Lance Yang <lance.yang@linux.dev>
Acked-by: Andrew Jeffery <andrew@codeconstruct.com.au> [aspeed_g5_defconfig]
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Florian Wesphal <fw@strlen.de>
Cc: Jakub Kacinski <kuba@kernel.org>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Simon Horman <horms@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
the added memory block itself do not be affected.
hung_task_panic=
- [KNL] Should the hung task detector generate panics.
- Format: 0 | 1
+ [KNL] Number of hung tasks to trigger kernel panic.
+ Format: <int>
+
+ When set to a non-zero value, a kernel panic will be triggered if
+ the number of detected hung tasks reaches this value.
+
+ 0: don't panic
+ 1: panic immediately on first hung task
+ N: panic after N hung tasks are detected in a single scan
- A value of 1 instructs the kernel to panic when a
- hung task is detected. The default value is controlled
- by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
- option. The value selected by this boot parameter can
- be changed later by the kernel.hung_task_panic sysctl.
+ The default value is controlled by the
+ CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time option. The value
+ selected by this boot parameter can be changed later by the
+ kernel.hung_task_panic sysctl.
hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
terminal devices. Valid values: 0..8
hung_task_panic
===============
-Controls the kernel's behavior when a hung task is detected.
+When set to a non-zero value, a kernel panic will be triggered if the
+number of hung tasks found during a single scan reaches this value.
This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
-= =================================================
+= =======================================================
0 Continue operation. This is the default behavior.
-1 Panic immediately.
-= =================================================
+N Panic when N hung tasks are found during a single scan.
+= =======================================================
hung_task_check_count
CONFIG_PANIC_TIMEOUT=-1
CONFIG_SOFTLOCKUP_DETECTOR=y
CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC=y
-CONFIG_BOOTPARAM_HUNG_TASK_PANIC=y
+CONFIG_BOOTPARAM_HUNG_TASK_PANIC=1
CONFIG_WQ_WATCHDOG=y
# CONFIG_SCHED_DEBUG is not set
CONFIG_FUNCTION_TRACER=y
#
# Debug Oops, Lockups and Hangs
#
-# CONFIG_BOOTPARAM_HUNG_TASK_PANIC is not set
+CONFIG_BOOTPARAM_HUNG_TASK_PANIC=0
# CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC is not set
CONFIG_DEBUG_ATOMIC_SLEEP=y
CONFIG_DETECT_HUNG_TASK=y
* hung task is detected:
*/
static unsigned int __read_mostly sysctl_hung_task_panic =
- IS_ENABLED(CONFIG_BOOTPARAM_HUNG_TASK_PANIC);
+ CONFIG_BOOTPARAM_HUNG_TASK_PANIC;
static int
hung_task_panic(struct notifier_block *this, unsigned long event, void *ptr)
}
#endif
-static void check_hung_task(struct task_struct *t, unsigned long timeout)
+static void check_hung_task(struct task_struct *t, unsigned long timeout,
+ unsigned long prev_detect_count)
{
+ unsigned long total_hung_task;
+
if (!task_is_hung(t, timeout))
return;
*/
sysctl_hung_task_detect_count++;
+ total_hung_task = sysctl_hung_task_detect_count - prev_detect_count;
trace_sched_process_hang(t);
- if (sysctl_hung_task_panic) {
+ if (sysctl_hung_task_panic && total_hung_task >= sysctl_hung_task_panic) {
console_verbose();
hung_task_show_lock = true;
hung_task_call_panic = true;
int max_count = sysctl_hung_task_check_count;
unsigned long last_break = jiffies;
struct task_struct *g, *t;
+ unsigned long prev_detect_count = sysctl_hung_task_detect_count;
/*
* If the system crashed already then all bets are off,
last_break = jiffies;
}
- check_hung_task(t, timeout);
+ check_hung_task(t, timeout, prev_detect_count);
}
unlock:
rcu_read_unlock();
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
+ .extra2 = SYSCTL_INT_MAX,
},
{
.procname = "hung_task_check_count",
Keeping the default should be fine in most cases.
config BOOTPARAM_HUNG_TASK_PANIC
- bool "Panic (Reboot) On Hung Tasks"
+ int "Number of hung tasks to trigger kernel panic"
depends on DETECT_HUNG_TASK
+ default 0
help
- Say Y here to enable the kernel to panic on "hung tasks",
- which are bugs that cause the kernel to leave a task stuck
- in uninterruptible "D" state.
+ When set to a non-zero value, a kernel panic will be triggered
+ if the number of hung tasks found during a single scan reaches
+ this value.
The panic can be used in combination with panic_timeout,
to cause the system to reboot automatically after a
CONFIG_DETECT_HUNG_TASK=y
CONFIG_BOOTPARAM_HARDLOCKUP_PANIC=y
CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC=y
-CONFIG_BOOTPARAM_HUNG_TASK_PANIC=y
+CONFIG_BOOTPARAM_HUNG_TASK_PANIC=1
CONFIG_PANIC_TIMEOUT=-1
CONFIG_STACKTRACE=y
CONFIG_EARLY_PRINTK=y
projects / thirdparty / kernel / linux.git / commitdiff
