From: Chuck Ebbert <cebbert.lkml@gmail.com>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Yuyang Du <yuyang.du@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
lkp@01.org
Subject: Re: [sched] BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
Date: Sat, 11 Oct 2014 01:00:48 -0500 [thread overview]
Message-ID: <20141011010048.7b9bfd54@as> (raw)
In-Reply-To: <20141011051530.GA21803@wfg-t540p.sh.intel.com>
On Sat, 11 Oct 2014 13:15:30 +0800
Fengguang Wu <fengguang.wu@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.
next prev parent reply other threads:[~2014-10-11 6:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-11 5:15 Fengguang Wu
2014-10-11 6:00 ` Chuck Ebbert [this message]
2014-10-10 22:23 ` Yuyang Du
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