From: Yuyang Du <yuyang.du@intel.com>
To: Chuck Ebbert <cebbert.lkml@gmail.com>
Cc: Fengguang Wu <fengguang.wu@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 06:23:20 +0800 [thread overview]
Message-ID: <20141010222320.GA5044@intel.com> (raw)
In-Reply-To: <20141011010048.7b9bfd54@as>
Yes, thanks.
How come it is sent to whole list. Please ignore this. Sorry.
On Sat, Oct 11, 2014 at 01:00:48AM -0500, Chuck Ebbert wrote:
> 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.
> --
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prev parent reply other threads:[~2014-10-11 6:23 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
2014-10-10 22:23 ` Yuyang Du [this message]
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