Messages in this thread | | | Date | Wed, 6 Apr 2016 08:54:36 +0200 | From | Ingo Molnar <> | Subject | Re: [tip:sched/core] sched/cpuacct: Split usage accounting into user_usage and sys_usage |
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* Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:
> * tip-bot for Dongsheng Yang <tipbot@zytor.com> [2016-03-31 02:27:39]: > > > Commit-ID: d740037fac7052e49450f6fa1454f1144a103b55 > > Gitweb: http://git.kernel.org/tip/d740037fac7052e49450f6fa1454f1144a103b55 > > Author: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> > > AuthorDate: Tue, 22 Mar 2016 16:37:08 +0800 > > Committer: Ingo Molnar <mingo@kernel.org> > > CommitDate: Thu, 31 Mar 2016 10:48:54 +0200 > > > > sched/cpuacct: Split usage accounting into user_usage and sys_usage > > > > Sometimes, cpuacct.usage is not detailed enough to see how much CPU > > usage a group had. We want to know how much time it used in user mode > > and how much in kernel mode. > > > > Unfortunately this commit causes boot to fail on my power 7 box. > > > @@ -238,10 +316,18 @@ static struct cftype files[] = { > > void cpuacct_charge(struct task_struct *tsk, u64 cputime) > > { > > struct cpuacct *ca; > > + int index; > > + > > + if (user_mode(task_pt_regs(tsk))) > > + index = CPUACCT_USAGE_USER; > > + else > > + index = CPUACCT_USAGE_SYSTEM; > > > > rcu_read_lock(); > > + > > for (ca = task_ca(tsk); ca; ca = parent_ca(ca)) > > - *this_cpu_ptr(ca->cpuusage) += cputime; > > + this_cpu_ptr(ca->cpuusage)->usages[index] += cputime; > > The above line seems to be the cause of oops. Attached the complete console log below.
Weird - not much changed wrt. the cpuusage logic, we only increased its size.
If you change the above loop to something like:
for (ca = task_ca(tsk); ca; ca = parent_ca(ca)) { if (WARN_ON_ONCE(!ca->cpuusage)) continue; this_cpu_ptr(ca->cpuusage)->usages[index] += cputime; }
then do you get the warning and the bootup succeeds?
Thanks,
Ingo
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