From: Anton Blanchard <anton@samba.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
tglx@linutronix.de, efault@gmx.de, htejun@gmail.com,
linux-kernel@vger.kernel.org, tj@kernel.org,
torvalds@linux-foundation.org, zhaolei@cn.fujitsu.com,
yangds.fnst@cn.fujitsu.com, hpa@zytor.com,
Stephen Rothwell <sfr@canb.auug.org.au>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs()
Date: Wed, 6 Apr 2016 21:59:50 +1000 [thread overview]
Message-ID: <20160406215950.04bc3f0b@kryten> (raw)
In-Reply-To: <20160406110803.GI2906@worktop>
Hi Peter,
> Ah, so sometihng like:
>
> struct pt_regs *regs = task_pt_regs();
> int index = CPUACCT_USAGE_SYSTEM;
>
> if (regs && user_mode(regs))
> index = CPUACCT_USAGE_USER;
>
> should work, right?
Looks good, and the patch below does fix the oops for me.
Anton
--
task_pt_regs() can return NULL for kernel threads, so add a check.
This fixes an oops at boot on ppc64.
Signed-off-by: Anton Blanchard <anton@samba.org>
---
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index df947e0..41f85c4 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -316,12 +316,11 @@ static struct cftype files[] = {
void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
struct cpuacct *ca;
- int index;
+ int index = CPUACCT_USAGE_SYSTEM;
+ struct pt_regs *regs = task_pt_regs(tsk);
- if (user_mode(task_pt_regs(tsk)))
+ if (regs && user_mode(regs))
index = CPUACCT_USAGE_USER;
- else
- index = CPUACCT_USAGE_SYSTEM;
rcu_read_lock();
next parent reply other threads:[~2016-04-06 12:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <aa171da036b520b51c79549e9b3215d29473f19d.1458635566.git.zhaolei@cn.fujitsu.com>
[not found] ` <tip-d740037fac7052e49450f6fa1454f1144a103b55@git.kernel.org>
[not found] ` <20160404140312.GA28495@linux.vnet.ibm.com>
[not found] ` <20160406065436.GB3078@gmail.com>
[not found] ` <20160406203219.788ae7cf@kryten>
[not found] ` <20160406110803.GI2906@worktop>
2016-04-06 11:59 ` Anton Blanchard [this message]
2016-04-06 13:26 ` [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() Srikar Dronamraju
2016-04-06 17:05 ` Zhao Lei
2016-04-13 7:43 ` Ingo Molnar
2016-04-13 11:01 ` Michael Ellerman
2016-04-13 11:21 ` Ingo Molnar
2016-04-11 6:16 ` Ping? " Michael Ellerman
2016-04-13 8:17 Anton Blanchard
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