Am 15.10.25 um 08:36 schrieb lirongqing:

quoted

From: Li RongQing <redacted>

Currently, when 'hung_task_panic' is enabled, the kernel panics
immediately upon detecting the first hung task. However, some hung
tasks are transient and allow system recovery, while persistent hangs
should trigger a panic when accumulating beyond a threshold.

Extend the 'hung_task_panic' sysctl to accept a threshold value
specifying the number of hung tasks that must be detected before
triggering a kernel panic. This provides finer control for
environments where transient hangs may occur but persistent hangs

should be fatal.

quoted

The sysctl now accepts:
- 0: don't panic (maintains original behavior)
- 1: panic on first hung task (maintains original behavior)
- N > 1: panic after N hung tasks are detected in a single scan

This maintains backward compatibility while providing flexibility for
different hang scenarios.

Signed-off-by: Li RongQing <redacted>
Cc: Andrew Jeffery <andrew@codeconstruct.com.au>
Cc: Anshuman Khandual <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Hildenbrand <redacted>
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: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <redacted>
Cc: Lorenzo Stoakes <redacted>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
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 <redacted>
Cc: Randy Dunlap <redacted>
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>
---
diff with v3: comments modification, suggested by Lance, Masami, Randy
and Petr diff with v2: do not add a new sysctl, extend
hung_task_panic, suggested by Kees Cook

  Documentation/admin-guide/kernel-parameters.txt      | 20

+++++++++++++-------

quoted

  Documentation/admin-guide/sysctl/kernel.rst          |  9 +++++----
  arch/arm/configs/aspeed_g5_defconfig                 |  2 +-
  kernel/configs/debug.config                          |  2 +-
  kernel/hung_task.c                                   | 15

++++++++++-----

quoted

  lib/Kconfig.debug                                    |  9

+++++----

quoted

  tools/testing/selftests/wireguard/qemu/kernel.config |  2 +-
  7 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt

b/Documentation/admin-guide/kernel-parameters.txt
index a51ab46..492f0bc 100644

--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt

@@ -1992,14 +1992,20 @@
  			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

quoted

+			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

quoted

+			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)

quoted

  				terminal devices. Valid values: 0..8 diff --git
a/Documentation/admin-guide/sysctl/kernel.rst
b/Documentation/admin-guide/sysctl/kernel.rst
index f3ee807..0065a55 100644

--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst

@@ -397,13 +397,14 @@ a hung task is detected.
  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

[…]

quoted

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index

3034e294..3976c90 100644

--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug

@@ -1258,12 +1258,13 @@ config DEFAULT_HUNG_TASK_TIMEOUT
  	  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

Why not leave the sentence about the uninterruptible "D" state in there?

This seem to say a kernel bug to cause hung task, but it maybe hardware failure(or virtio backend bug); so I do not keep it

Also, it sounds like, some are actually using this in production. Maybe it
should be moved out of `Kconfig.debug` too?

I think hung task panic is a useful feature, it should move out of Kconfig.debug

Thanks

-Li

Kind regards,

Paul