Re: cgroup_fj tests will stick the nort kernel

[Qiang Huang <h.huangqiang@huawei.com>]

On 2013/4/25 16:44, Li Zefan wrote:
>> And the patch below, I added your signed-off-by if it looks good to you.
> 
> Don't...
> 
>> Here is the patch seems solve the problem, it looks all good in my box, my
>> only concern is how will this affect our RT code.
>>
>>
>> >From 8e4fa4e9a7b510bdaf90b8140ce1e847375abccf Mon Sep 17 00:00:00 2001
>> From: Qiang Huang <h.huangqiang@huawei.com>
>> Date: Thu, 25 Apr 2013 10:22:01 +0800
>> Subject: [PATCH] sched: don't clear PF_THREAD_BOUND in select_fallback_rq
>>
>> This is revert of "sched-clear-pf-thread-bound-on-fallback-rq.patch"
>> (commit 0d939066acdcb in v3.4-rt),.
>>
>> Select_fallback_rq() can be easilly called during system boot, because
>> select_task_rq_fair() just return task_cpu(p) for bounded kernel threads,
>> which is 0 during system boot and not in tsk_cpus_allowed, so
>> select_fallback_rq() is called and PF_THREAD_BOUND is cleared. In my
>> box, 1/3 bounded kernel threads will clear that flag after boot.
>>
>> And it will cause problems, for example:
>> # for pid in `ps -e -o pid`; do taskset -p -c 0-15 $pid; done
>> this command will cause system hung.
>>
>> What's more, I don't see why we need to clear this flag any more,
>> because "cpu/rt: Rework cpu down for PREEMPT_RT" already remove the
>> optimization for PF_THREAD_BOUND on migrate_disable/enable.
>>
>> Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
>> Signed-off-by: Li Zefan <lizefan@huawei.com>
> 
> You shoudn't have added my SOB... I didn't write this patch and I didn't
> even sugguest this fix or check if this is a correct fix.
> 
> Please read Documentation/SubmittingPatches to learn how SOB should
> be used.
> 

OK, I'll resend it.