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hung_task: add hung_task_sys_info sysctl to dump sys info on task-hung

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When task-hung happens, developers may need different kinds of system
information (call-stacks, memory info, locks, etc.) to help debugging.

Add 'hung_task_sys_info' sysctl knob to take human readable string like
"tasks,mem,timers,locks,ftrace,...", and when task-hung happens, all
requested information will be dumped.  (refer kernel/sys_info.c for more
details).

Meanwhile, the newly introduced sys_info() call is used to unify some
existing info-dumping knobs.

[feng.tang@linux.alibaba.com: maintain consistecy established behavior, per Lance and Petr]
  Link: https://lkml.kernel.org/r/aRncJo1mA5Zk77Hr@U-2FWC9VHC-2323.local
Link: https://lkml.kernel.org/r/20251113111039.22701-3-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Feng Tang
2025-11-13 19:10:37 +08:00
committed by Andrew Morton
parent 5f264c00b6
commit 8b2b9b4f6f
2 changed files with 33 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
Documentation/admin-guide/sysctl/kernel.rst
View File

@@ -422,6 +422,11 @@ the system boot.
This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
hung_task_sys_info
==================
A comma separated list of extra system information to be dumped when
hung task is detected, for example, "tasks,mem,timers,locks,...".
Refer 'panic_sys_info' section below for more details.
hung_task_timeout_secs
======================

40
kernel/hung_task.c
View File

@@ -24,6 +24,7 @@
#include <linux/sched/sysctl.h>
#include <linux/hung_task.h>
#include <linux/rwsem.h>
#include <linux/sys_info.h>
#include <trace/events/sched.h>
@@ -59,12 +60,17 @@ static unsigned long __read_mostly sysctl_hung_task_check_interval_secs;
static int __read_mostly sysctl_hung_task_warnings = 10;
static int __read_mostly did_panic;
static bool hung_task_show_lock;
static bool hung_task_call_panic;
static bool hung_task_show_all_bt;
static struct task_struct *watchdog_task;
/*
* A bitmask to control what kinds of system info to be printed when
* a hung task is detected, it could be task, memory, lock etc. Refer
* include/linux/sys_info.h for detailed bit definition.
*/
static unsigned long hung_task_si_mask;
#ifdef CONFIG_SMP
/*
* Should we dump all CPUs backtraces in a hung task event?
@@ -236,7 +242,6 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout,
if (sysctl_hung_task_panic && total_hung_task >= sysctl_hung_task_panic) {
console_verbose();
hung_task_show_lock = true;
hung_task_call_panic = true;
}
@@ -259,10 +264,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout,
" disables this message.\n");
sched_show_task(t);
debug_show_blocker(t, timeout);
hung_task_show_lock = true;
if (sysctl_hung_task_all_cpu_backtrace)
hung_task_show_all_bt = true;
if (!sysctl_hung_task_warnings)
pr_info("Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings\n");
}
@@ -304,6 +306,8 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
unsigned long last_break = jiffies;
struct task_struct *g, *t;
unsigned long prev_detect_count = sysctl_hung_task_detect_count;
int need_warning = sysctl_hung_task_warnings;
unsigned long si_mask = hung_task_si_mask;
/*
* If the system crashed already then all bets are off,
@@ -312,7 +316,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
if (test_taint(TAINT_DIE) || did_panic)
return;
hung_task_show_lock = false;
rcu_read_lock();
for_each_process_thread(g, t) {
@@ -328,14 +332,19 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
}
unlock:
rcu_read_unlock();
if (hung_task_show_lock)
debug_show_all_locks();
if (hung_task_show_all_bt) {
hung_task_show_all_bt = false;
trigger_all_cpu_backtrace();
if (!(sysctl_hung_task_detect_count - prev_detect_count))
return;
if (need_warning || hung_task_call_panic) {
si_mask |= SYS_INFO_LOCKS;
if (sysctl_hung_task_all_cpu_backtrace)
si_mask |= SYS_INFO_ALL_BT;
}
sys_info(si_mask);
if (hung_task_call_panic)
panic("hung_task: blocked tasks");
}
@@ -434,6 +443,13 @@ static const struct ctl_table hung_task_sysctls[] = {
.mode = 0444,
.proc_handler = proc_doulongvec_minmax,
},
{
.procname = "hung_task_sys_info",
.data = &hung_task_si_mask,
.maxlen = sizeof(hung_task_si_mask),
.mode = 0644,
.proc_handler = sysctl_sys_info_handler,
},
};
static void __init hung_task_sysctl_init(void)