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watchdog: add sys_info sysctls to dump sys info on system lockup

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

Add 'softlockup_sys_info' and 'hardlockup_sys_info' sysctl knobs to take
human readable string like "tasks,mem,timers,locks,ftrace,...", and when
system lockup happens, all requested information will be printed out. 
(refer kernel/sys_info.c for more details).

Link: https://lkml.kernel.org/r/20251113111039.22701-4-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
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 19:10:38 +08:00
committed by Andrew Morton
parent 8b2b9b4f6f
commit a9af76a787
2 changed files with 46 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

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

@@ -582,6 +582,11 @@ if leaking kernel pointer values to unprivileged users is a concern.
When ``kptr_restrict`` is set to 2, kernel pointers printed using
%pK will be replaced with 0s regardless of privileges.
softlockup_sys_info & hardlockup_sys_info
=========================================
A comma separated list of extra system information to be dumped when
soft/hard lockup is detected, for example, "tasks,mem,timers,locks,...".
Refer 'panic_sys_info' section below for more details.
modprobe
========

44
kernel/watchdog.c
View File

@@ -25,6 +25,7 @@
#include <linux/stop_machine.h>
#include <linux/sysctl.h>
#include <linux/tick.h>
#include <linux/sys_info.h>
#include <linux/sched/clock.h>
#include <linux/sched/debug.h>
@@ -65,6 +66,13 @@ int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
unsigned int __read_mostly hardlockup_panic =
IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC);
/*
* bitmasks to control what kinds of system info to be printed when
* hard lockup is detected, it could be task, memory, lock etc.
* Refer include/linux/sys_info.h for detailed bit definition.
*/
static unsigned long hardlockup_si_mask;
#ifdef CONFIG_SYSFS
static unsigned int hardlockup_count;
@@ -178,11 +186,15 @@ static void watchdog_hardlockup_kick(void)
void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
{
int hardlockup_all_cpu_backtrace;
if (per_cpu(watchdog_hardlockup_touched, cpu)) {
per_cpu(watchdog_hardlockup_touched, cpu) = false;
return;
}
hardlockup_all_cpu_backtrace = (hardlockup_si_mask & SYS_INFO_ALL_BT) ?
1 : sysctl_hardlockup_all_cpu_backtrace;
/*
* Check for a hardlockup by making sure the CPU's timer
* interrupt is incrementing. The timer interrupt should have
@@ -205,7 +217,7 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
* Prevent multiple hard-lockup reports if one cpu is already
* engaged in dumping all cpu back traces.
*/
if (sysctl_hardlockup_all_cpu_backtrace) {
if (hardlockup_all_cpu_backtrace) {
if (test_and_set_bit_lock(0, &hard_lockup_nmi_warn))
return;
}
@@ -234,12 +246,13 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
trigger_single_cpu_backtrace(cpu);
}
if (sysctl_hardlockup_all_cpu_backtrace) {
if (hardlockup_all_cpu_backtrace) {
trigger_allbutcpu_cpu_backtrace(cpu);
if (!hardlockup_panic)
clear_bit_unlock(0, &hard_lockup_nmi_warn);
}
sys_info(hardlockup_si_mask & ~SYS_INFO_ALL_BT);
if (hardlockup_panic)
nmi_panic(regs, "Hard LOCKUP");
@@ -330,6 +343,13 @@ static void lockup_detector_update_enable(void)
int __read_mostly sysctl_softlockup_all_cpu_backtrace;
#endif
/*
* bitmasks to control what kinds of system info to be printed when
* soft lockup is detected, it could be task, memory, lock etc.
* Refer include/linux/sys_info.h for detailed bit definition.
*/
static unsigned long softlockup_si_mask;
static struct cpumask watchdog_allowed_mask __read_mostly;
/* Global variables, exported for sysctl */
@@ -746,7 +766,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
unsigned long touch_ts, period_ts, now;
struct pt_regs *regs = get_irq_regs();
int duration;
int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
int softlockup_all_cpu_backtrace;
unsigned long flags;
if (!watchdog_enabled)
@@ -758,6 +778,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
if (panic_in_progress())
return HRTIMER_NORESTART;
softlockup_all_cpu_backtrace = (softlockup_si_mask & SYS_INFO_ALL_BT) ?
1 : sysctl_softlockup_all_cpu_backtrace;
watchdog_hardlockup_kick();
/* kick the softlockup detector */
@@ -846,6 +869,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
}
add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
sys_info(softlockup_si_mask & ~SYS_INFO_ALL_BT);
if (softlockup_panic)
panic("softlockup: hung tasks");
}
@@ -1197,6 +1221,13 @@ static const struct ctl_table watchdog_sysctls[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
{
.procname = "softlockup_sys_info",
.data = &softlockup_si_mask,
.maxlen = sizeof(softlockup_si_mask),
.mode = 0644,
.proc_handler = sysctl_sys_info_handler,
},
#ifdef CONFIG_SMP
{
.procname = "softlockup_all_cpu_backtrace",
@@ -1219,6 +1250,13 @@ static const struct ctl_table watchdog_sysctls[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
{
.procname = "hardlockup_sys_info",
.data = &hardlockup_si_mask,
.maxlen = sizeof(hardlockup_si_mask),
.mode = 0644,
.proc_handler = sysctl_sys_info_handler,
},
#ifdef CONFIG_SMP
{
.procname = "hardlockup_all_cpu_backtrace",