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Diffstat (limited to 'kernel/lockdep.c')
-rw-r--r--kernel/lockdep.c53
1 files changed, 43 insertions, 10 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 24f176c9fc9f..8889f7dd7c46 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -431,6 +431,7 @@ unsigned int max_lockdep_depth;
* about it later on, in lockdep_info().
*/
static int lockdep_init_error;
+static const char *lock_init_error;
static unsigned long lockdep_init_trace_data[20];
static struct stack_trace lockdep_init_trace = {
.max_entries = ARRAY_SIZE(lockdep_init_trace_data),
@@ -564,11 +565,12 @@ static void lockdep_print_held_locks(struct task_struct *curr)
}
}
-static void print_kernel_version(void)
+static void print_kernel_ident(void)
{
- printk("%s %.*s\n", init_utsname()->release,
+ printk("%s %.*s %s\n", init_utsname()->release,
(int)strcspn(init_utsname()->version, " "),
- init_utsname()->version);
+ init_utsname()->version,
+ print_tainted());
}
static int very_verbose(struct lock_class *class)
@@ -652,6 +654,7 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
if (unlikely(!lockdep_initialized)) {
lockdep_init();
lockdep_init_error = 1;
+ lock_init_error = lock->name;
save_stack_trace(&lockdep_init_trace);
}
#endif
@@ -719,7 +722,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
class = look_up_lock_class(lock, subclass);
if (likely(class))
- return class;
+ goto out_set_class_cache;
/*
* Debug-check: all keys must be persistent!
@@ -804,6 +807,7 @@ out_unlock_set:
graph_unlock();
raw_local_irq_restore(flags);
+out_set_class_cache:
if (!subclass || force)
lock->class_cache[0] = class;
else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
@@ -1145,7 +1149,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth,
printk("\n");
printk("======================================================\n");
printk("[ INFO: possible circular locking dependency detected ]\n");
- print_kernel_version();
+ print_kernel_ident();
printk("-------------------------------------------------------\n");
printk("%s/%d is trying to acquire lock:\n",
curr->comm, task_pid_nr(curr));
@@ -1484,7 +1488,7 @@ print_bad_irq_dependency(struct task_struct *curr,
printk("======================================================\n");
printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
irqclass, irqclass);
- print_kernel_version();
+ print_kernel_ident();
printk("------------------------------------------------------\n");
printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
curr->comm, task_pid_nr(curr),
@@ -1713,7 +1717,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
printk("\n");
printk("=============================================\n");
printk("[ INFO: possible recursive locking detected ]\n");
- print_kernel_version();
+ print_kernel_ident();
printk("---------------------------------------------\n");
printk("%s/%d is trying to acquire lock:\n",
curr->comm, task_pid_nr(curr));
@@ -2220,7 +2224,7 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
printk("\n");
printk("=================================\n");
printk("[ INFO: inconsistent lock state ]\n");
- print_kernel_version();
+ print_kernel_ident();
printk("---------------------------------\n");
printk("inconsistent {%s} -> {%s} usage.\n",
@@ -2285,7 +2289,7 @@ print_irq_inversion_bug(struct task_struct *curr,
printk("\n");
printk("=========================================================\n");
printk("[ INFO: possible irq lock inversion dependency detected ]\n");
- print_kernel_version();
+ print_kernel_ident();
printk("---------------------------------------------------------\n");
printk("%s/%d just changed the state of lock:\n",
curr->comm, task_pid_nr(curr));
@@ -3171,6 +3175,7 @@ print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
printk("\n");
printk("=====================================\n");
printk("[ BUG: bad unlock balance detected! ]\n");
+ print_kernel_ident();
printk("-------------------------------------\n");
printk("%s/%d is trying to release lock (",
curr->comm, task_pid_nr(curr));
@@ -3615,6 +3620,7 @@ print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
printk("\n");
printk("=================================\n");
printk("[ BUG: bad contention detected! ]\n");
+ print_kernel_ident();
printk("---------------------------------\n");
printk("%s/%d is trying to contend lock (",
curr->comm, task_pid_nr(curr));
@@ -3970,7 +3976,8 @@ void __init lockdep_info(void)
#ifdef CONFIG_DEBUG_LOCKDEP
if (lockdep_init_error) {
- printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
+ printk("WARNING: lockdep init error! lock-%s was acquired"
+ "before lockdep_init\n", lock_init_error);
printk("Call stack leading to lockdep invocation was:\n");
print_stack_trace(&lockdep_init_trace, 0);
}
@@ -3989,6 +3996,7 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
printk("\n");
printk("=========================\n");
printk("[ BUG: held lock freed! ]\n");
+ print_kernel_ident();
printk("-------------------------\n");
printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
@@ -4046,6 +4054,7 @@ static void print_held_locks_bug(struct task_struct *curr)
printk("\n");
printk("=====================================\n");
printk("[ BUG: lock held at task exit time! ]\n");
+ print_kernel_ident();
printk("-------------------------------------\n");
printk("%s/%d is exiting with locks still held!\n",
curr->comm, task_pid_nr(curr));
@@ -4143,6 +4152,7 @@ void lockdep_sys_exit(void)
printk("\n");
printk("================================================\n");
printk("[ BUG: lock held when returning to user space! ]\n");
+ print_kernel_ident();
printk("------------------------------------------------\n");
printk("%s/%d is leaving the kernel with locks still held!\n",
curr->comm, curr->pid);
@@ -4162,10 +4172,33 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
printk("\n");
printk("===============================\n");
printk("[ INFO: suspicious RCU usage. ]\n");
+ print_kernel_ident();
printk("-------------------------------\n");
printk("%s:%d %s!\n", file, line, s);
printk("\nother info that might help us debug this:\n\n");
printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
+
+ /*
+ * If a CPU is in the RCU-free window in idle (ie: in the section
+ * between rcu_idle_enter() and rcu_idle_exit(), then RCU
+ * considers that CPU to be in an "extended quiescent state",
+ * which means that RCU will be completely ignoring that CPU.
+ * Therefore, rcu_read_lock() and friends have absolutely no
+ * effect on a CPU running in that state. In other words, even if
+ * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
+ * delete data structures out from under it. RCU really has no
+ * choice here: we need to keep an RCU-free window in idle where
+ * the CPU may possibly enter into low power mode. This way we can
+ * notice an extended quiescent state to other CPUs that started a grace
+ * period. Otherwise we would delay any grace period as long as we run
+ * in the idle task.
+ *
+ * So complain bitterly if someone does call rcu_read_lock(),
+ * rcu_read_lock_bh() and so on from extended quiescent states.
+ */
+ if (rcu_is_cpu_idle())
+ printk("RCU used illegally from extended quiescent state!\n");
+
lockdep_print_held_locks(curr);
printk("\nstack backtrace:\n");
dump_stack();