diff options
Diffstat (limited to 'kernel/hung_task.c')
| -rw-r--r-- | kernel/hung_task.c | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 04efa7a6e69b..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> @@ -93,6 +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; @@ -152,6 +222,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) 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) |