diff options
Diffstat (limited to 'kernel/hung_task.c')
| -rw-r--r-- | kernel/hung_task.c | 98 |
1 files changed, 94 insertions, 4 deletions
diff --git a/kernel/hung_task.c b/kernel/hung_task.c index b2fc2727d654..d2432df2b905 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -22,6 +22,7 @@ #include <linux/sched/signal.h> #include <linux/sched/debug.h> #include <linux/sched/sysctl.h> +#include <linux/hung_task.h> #include <trace/events/sched.h> @@ -31,6 +32,11 @@ static int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT; /* + * Total number of tasks detected as hung since boot: + */ +static unsigned long __read_mostly sysctl_hung_task_detect_count; + +/* * Limit number of tasks checked in a batch. * * This value controls the preemptibility of khungtaskd since preemption @@ -88,6 +94,75 @@ static struct notifier_block panic_block = { .notifier_call = hung_task_panic, }; + +#ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER +static void debug_show_blocker(struct task_struct *task) +{ + struct task_struct *g, *t; + unsigned long owner, blocker, blocker_type; + + RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "No rcu lock held"); + + blocker = READ_ONCE(task->blocker); + if (!blocker) + return; + + blocker_type = hung_task_get_blocker_type(blocker); + + switch (blocker_type) { + case BLOCKER_TYPE_MUTEX: + owner = mutex_get_owner( + (struct mutex *)hung_task_blocker_to_lock(blocker)); + break; + case BLOCKER_TYPE_SEM: + owner = sem_last_holder( + (struct semaphore *)hung_task_blocker_to_lock(blocker)); + break; + default: + WARN_ON_ONCE(1); + return; + } + + + if (unlikely(!owner)) { + switch (blocker_type) { + case BLOCKER_TYPE_MUTEX: + pr_err("INFO: task %s:%d is blocked on a mutex, but the owner is not found.\n", + task->comm, task->pid); + break; + case BLOCKER_TYPE_SEM: + pr_err("INFO: task %s:%d is blocked on a semaphore, but the last holder is not found.\n", + task->comm, task->pid); + break; + } + return; + } + + /* Ensure the owner information is correct. */ + for_each_process_thread(g, t) { + if ((unsigned long)t != owner) + continue; + + switch (blocker_type) { + case BLOCKER_TYPE_MUTEX: + pr_err("INFO: task %s:%d is blocked on a mutex likely owned by task %s:%d.\n", + task->comm, task->pid, t->comm, t->pid); + break; + case BLOCKER_TYPE_SEM: + pr_err("INFO: task %s:%d blocked on a semaphore likely last held by task %s:%d\n", + task->comm, task->pid, t->comm, t->pid); + break; + } + sched_show_task(t); + return; + } +} +#else +static inline void debug_show_blocker(struct task_struct *task) +{ +} +#endif + static void check_hung_task(struct task_struct *t, unsigned long timeout) { unsigned long switch_count = t->nvcsw + t->nivcsw; @@ -115,6 +190,12 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) if (time_is_after_jiffies(t->last_switch_time + timeout * HZ)) return; + /* + * This counter tracks the total number of tasks detected as hung + * since boot. + */ + sysctl_hung_task_detect_count++; + trace_sched_process_hang(t); if (sysctl_hung_task_panic) { @@ -127,7 +208,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) * Ok, the task did not get scheduled for more than 2 minutes, * complain: */ - if (sysctl_hung_task_warnings) { + if (sysctl_hung_task_warnings || hung_task_call_panic) { if (sysctl_hung_task_warnings > 0) sysctl_hung_task_warnings--; pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n", @@ -136,9 +217,12 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) print_tainted(), init_utsname()->release, (int)strcspn(init_utsname()->version, " "), init_utsname()->version); + if (t->flags & PF_POSTCOREDUMP) + pr_err(" Blocked by coredump.\n"); pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\"" " disables this message.\n"); sched_show_task(t); + debug_show_blocker(t); hung_task_show_lock = true; if (sysctl_hung_task_all_cpu_backtrace) @@ -239,7 +323,7 @@ static long hung_timeout_jiffies(unsigned long last_checked, /* * Process updating of timeout sysctl */ -static int proc_dohung_task_timeout_secs(struct ctl_table *table, int write, +static int proc_dohung_task_timeout_secs(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { @@ -261,7 +345,7 @@ static int proc_dohung_task_timeout_secs(struct ctl_table *table, int write, * and hung_task_check_interval_secs */ static const unsigned long hung_task_timeout_max = (LONG_MAX / HZ); -static struct ctl_table hung_task_sysctls[] = { +static const struct ctl_table hung_task_sysctls[] = { #ifdef CONFIG_SMP { .procname = "hung_task_all_cpu_backtrace", @@ -314,7 +398,13 @@ static struct ctl_table hung_task_sysctls[] = { .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_NEG_ONE, }, - {} + { + .procname = "hung_task_detect_count", + .data = &sysctl_hung_task_detect_count, + .maxlen = sizeof(unsigned long), + .mode = 0444, + .proc_handler = proc_doulongvec_minmax, + }, }; static void __init hung_task_sysctl_init(void) |