On Sat, 11 Oct 2014 13:15:30 +0800
Fengguang Wu <fengguang...@intel.com> wrote:
> FYI, we noticed the below changes on commit
>
> 445d95d7c384741d133251a9adac935866591c92 ("sched: Remove
> update_rq_runnable_avg")
>
> [ 67.303839] BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000040
> [ 67.304014] IP: [<ffffffff810b1d52>] print_cfs_rq+0x4a3/0xa96
Well that one's pretty obvious:
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -68,14 +68,6 @@ static void print_cfs_group_stats(struct seq_file *m, int
cpu, struct task_group
#define PN(F) \
SEQ_printf(m, " .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
- if (!se) {
- struct sched_avg *avg = &cpu_rq(cpu)->avg;
- P(avg->runnable_avg_sum);
- P(avg->runnable_avg_period);
- return;
- }
-
-
PN(se->exec_start);
PN(se->vruntime);
PN(se->sum_exec_runtime);
You can remove the P() calls from that if statement, but you can't
remove the whole thing because you will try to dereference a NULL se
immediately afterward if you do.
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