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rcu: refer RCU CPU stall-warning victims to stallwarn.txt 

There is some documentation on RCU CPU stall warnings contained in
Documentation/RCU/stallwarn.txt, but it will not be apparent to someone
who runs into such a warning while under time pressure.  This commit
therefore adds comments preceding the printk()s pointing out the
location of this documentation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2010-08-09 14:23:03 -07:00
parent 9079fd7c2e
commit 8cdd32a918
1 changed files with 10 additions and 2 deletions
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12
kernel/rcutree.c
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@ -487,8 +487,11 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
rcu_print_task_stall(rnp); rcu_print_task_stall(rnp);
raw_spin_unlock_irqrestore(&rnp->lock, flags); raw_spin_unlock_irqrestore(&rnp->lock, flags);
/* OK, time to rat on our buddy... */ /*
* OK, time to rat on our buddy...
* See Documentation/RCU/stallwarn.txt for info on how to debug
* RCU CPU stall warnings.
*/
printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {", printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {",
rsp->name); rsp->name);
rcu_for_each_leaf_node(rsp, rnp) { rcu_for_each_leaf_node(rsp, rnp) {
@ -517,6 +520,11 @@ static void print_cpu_stall(struct rcu_state *rsp)
unsigned long flags; unsigned long flags;
struct rcu_node *rnp = rcu_get_root(rsp); struct rcu_node *rnp = rcu_get_root(rsp);
/*
* OK, time to rat on ourselves...
* See Documentation/RCU/stallwarn.txt for info on how to debug
* RCU CPU stall warnings.
*/
printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n",
rsp->name, smp_processor_id(), jiffies - rsp->gp_start); rsp->name, smp_processor_id(), jiffies - rsp->gp_start);
trigger_all_cpu_backtrace(); trigger_all_cpu_backtrace();