Commit c4f3b63f authored by Ravikiran G Thirumalai's avatar Ravikiran G Thirumalai Committed by Linus Torvalds

softlockup: add a /proc tuning parameter

Control the trigger limit for softlockup warnings.  This is useful for
debugging softlockups, by lowering the softlockup_thresh to identify
possible softlockups earlier.

This patch:
1. Adds a sysctl softlockup_thresh with valid values of 1-60s
   (Higher value to disable false positives)
2. Changes the softlockup printk to print the cpu softlockup time

[akpm@linux-foundation.org: Fix various warnings and add definition of "two"]
Signed-off-by: default avatarRavikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: default avatarShai Fultheim <shai@scalex86.org>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a5f2ce3c
......@@ -320,6 +320,14 @@ kernel. This value defaults to SHMMAX.
==============================================================
softlockup_thresh:
This value can be used to lower the softlockup tolerance
threshold. The default threshold is 10s. If a cpu is locked up
for 10s, the kernel complains. Valid values are 1-60s.
==============================================================
tainted:
Non-zero if the kernel has been tainted. Numeric values, which
......
......@@ -261,6 +261,7 @@ extern void softlockup_tick(void);
extern void spawn_softlockup_task(void);
extern void touch_softlockup_watchdog(void);
extern void touch_all_softlockup_watchdogs(void);
extern int softlockup_thresh;
#else
static inline void softlockup_tick(void)
{
......
......@@ -24,6 +24,7 @@ static DEFINE_PER_CPU(unsigned long, print_timestamp);
static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
static int did_panic;
int softlockup_thresh = 10;
static int
softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
......@@ -104,13 +105,15 @@ void softlockup_tick(void)
wake_up_process(per_cpu(watchdog_task, this_cpu));
/* Warn about unreasonable 10+ seconds delays: */
if (now <= (touch_timestamp + 10))
if (now <= (touch_timestamp + softlockup_thresh))
return;
per_cpu(print_timestamp, this_cpu) = touch_timestamp;
spin_lock(&print_lock);
printk(KERN_ERR "BUG: soft lockup detected on CPU#%d!\n", this_cpu);
printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
this_cpu, now - touch_timestamp,
current->comm, current->pid);
if (regs)
show_regs(regs);
else
......
......@@ -80,6 +80,19 @@ extern int maps_protect;
extern int sysctl_stat_interval;
extern int audit_argv_kb;
/* Constants used for minimum and maximum */
#ifdef CONFIG_DETECT_SOFTLOCKUP
static int one = 1;
static int sixty = 60;
#endif
#ifdef CONFIG_MMU
static int two = 2;
#endif
static int zero;
static int one_hundred = 100;
/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
static int maxolduid = 65535;
static int minolduid;
......@@ -711,6 +724,19 @@ static ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
#endif
#ifdef CONFIG_DETECT_SOFTLOCKUP
{
.ctl_name = CTL_UNNUMBERED,
.procname = "softlockup_thresh",
.data = &softlockup_thresh,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &one,
.extra2 = &sixty,
},
#endif
#ifdef CONFIG_COMPAT
{
.ctl_name = KERN_COMPAT_LOG,
......@@ -757,13 +783,6 @@ static ctl_table kern_table[] = {
{ .ctl_name = 0 }
};
/* Constants for minimum and maximum testing in vm_table.
We use these as one-element integer vectors. */
static int zero;
static int two = 2;
static int one_hundred = 100;
static ctl_table vm_table[] = {
{
.ctl_name = VM_OVERCOMMIT_MEMORY,
......
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