Hi Chirag,
Please apply this patch to your 26.5-rt9 tree for ppc64, enable
CONFIG_PROVE_LOCKING (which enables CONFIG_STACKTRACE) and give it a whirl.
If you get an oops, please post the console output.
Thanks!
-Greg
------------------
sched: add a stacktrace on enqueue_pushable error
NOT FOR INCLUSION!
This is to help debug an issue discovered by Chirag Jog in the thread
http://lkml.org/lkml/2008/9/25/189
Signed-off-by: Gregory Haskins <ghaskins@novell.com>
---
include/linux/sched.h | 6 ++++++
kernel/sched_rt.c | 20 +++++++++++++++++++-
2 files changed, 25 insertions(+), 1 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 67da014..53e8a6a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -87,6 +87,7 @@ struct sched_param {
#include <linux/task_io_accounting.h>
#include <linux/kobject.h>
#include <linux/latencytop.h>
+#include <linux/stacktrace.h>
#include <asm/processor.h>
@@ -1170,6 +1171,11 @@ struct task_struct {
struct list_head tasks;
struct plist_node pushable_tasks;
+ struct {
+ unsigned long data[15];
+ struct stack_trace trace;
+ pid_t pid;
+ } pushable_stack;
/*
* ptrace_list/ptrace_children forms the list of my children
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 57a0c0d..0e6a88c 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -55,7 +55,25 @@ static void update_rt_migration(struct rq *rq)
static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
{
- plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
+ if (plist_node_empty(&p->pushable_tasks)) {
+ struct stack_trace *trace = &p->pushable_stack.trace;
+
+ trace->nr_entries = 0;
+ trace->max_entries = sizeof(p->pushable_stack.data)/sizeof(p->pushable_stack.data[0]);
+ trace->entries = &p->pushable_stack.data[0];
+ trace->skip = 0;
+
+ save_stack_trace(trace);
+
+ p->pushable_stack.pid = current->pid;
+ } else {
+ printk(KERN_CRIT "redundant enqueue by %d detected\n",
+ p->pushable_stack.pid);
+ print_stack_trace(&p->pushable_stack.trace, 5);
+
+ BUG_ON(!plist_node_empty(&p->pushable_tasks));
+ }
+
plist_node_init(&p->pushable_tasks, p->prio);
plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
}
--
