linux-kernel - Re: [PATCH RESEND v4] sched: fix llc shared map unreleased during cpu hotplug

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Date:	Tue, 9 Sep 2014 00:40:22 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Wanpeng Li <wanpeng.li@...ux.intel.com>
Cc:	Mike Galbraith <umgwanakikbuti@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"x86@...nel.org" <x86@...nel.org>, Borislav Petkov <bp@...en8.de>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	David Rientjes <rientjes@...gle.com>,
	Prarit Bhargava <prarit@...hat.com>,
	Steven Rostedt <srostedt@...hat.com>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Toshi Kani <toshi.kani@...com>,
	Zhang Yang <yang.z.zhang@...el.com>
Subject: Re: [PATCH RESEND v4] sched: fix llc shared map unreleased during cpu hotplug

I didn't look at it that hard since it claimed to be a sched patch.  I prioritize things in my inbox which say x86 for obvious reasons.  Since I have over 12,000 unread messages in my inbox alone...

Sent from my tablet, pardon any formatting problems.

> On Sep 9, 2014, at 0:24, Wanpeng Li <wanpeng.li@...ux.intel.com> wrote:
> 
> Hi Mike,
>> On Tue, Sep 09, 2014 at 09:06:32AM +0200, Mike Galbraith wrote:
>> Hm, this patchlet seems to be having trouble taking wing.
>> 
>> (tosses it up in the air.. flap yer little wings patchlet)
>> 
>> I thought you had changed the title to..
>> 
>> x86,cpu-hotplug: clear llc_shared_mask at CPU hotplug
>> 
>> ..due to Peter saying sched is only a consumer, but v4 somehow reverted
>> back to being a sched patch.
> 
> I send out the RESEND v4 by a mistake, please refer the below link for the patch.
> https://lkml.org/lkml/2014/7/29/159
> 
> Regards,
> Wanpeng Li 
> 
>>> On Mon, 2014-08-25 at 13:49 +0800, Wanpeng Li wrote: 
>>> [  220.262245] Call Trace:
>>> [  220.262252]  [<ffffffff810e8396>] load_balance+0x156/0x980
>>> [  220.262259]  [<ffffffff816eeffe>] ? _raw_spin_unlock_irqrestore+0x2e/0xa0
>>> [  220.262266]  [<ffffffff810e9aa3>] idle_balance+0xe3/0x150
>>> [  220.262270]  [<ffffffff816ec4e7>] __schedule+0x797/0x8d0
>>> [  220.262277]  [<ffffffff816ec934>] schedule+0x24/0x70
>>> [  220.262283]  [<ffffffff816e9cd9>] schedule_timeout+0x119/0x1f0
>>> [  220.262294]  [<ffffffff810bb6e0>] ? lock_timer_base+0x70/0x70
>>> [  220.262301]  [<ffffffff816e9dc9>] schedule_timeout_uninterruptible+0x19/0x20
>>> [  220.262308]  [<ffffffff810bd3e8>] msleep+0x18/0x20
>>> [  220.262317]  [<ffffffff813aa11a>] lock_device_hotplug_sysfs+0x2a/0x50
>>> [  220.262323]  [<ffffffff813aa16e>] online_store+0x2e/0x80
>>> [  220.262358]  [<ffffffff813a873b>] dev_attr_store+0x1b/0x20
>>> 
>>> Last level cache shared map is built during cpu up and build sched domain 
>>> routine takes advantage of it to setup sched domain cpu topology, however, 
>>> llc shared map is unreleased during cpu disable which lead to invalid sched 
>>> domain cpu topology. This patch fix it by release llc shared map correctly
>>> during cpu disable.
>>> 
>>> Reviewed-by: Toshi Kani <toshi.kani@...com>
>>> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
>>> Tested-by: Linn Crosetto <linn@...com>
>>> Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
>>> ---
>>> v3 -> v4:
>>> * simplify backtrace
>>> v2 -> v3:
>>> * simplify backtrace 
>>> v1 -> v2:
>>> * fix subject line
>>> 
>>> arch/x86/kernel/smpboot.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>> 
>>> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
>>> index 5492798..0134ec7 100644
>>> --- a/arch/x86/kernel/smpboot.c
>>> +++ b/arch/x86/kernel/smpboot.c
>>> @@ -1292,6 +1292,9 @@ static void remove_siblinginfo(int cpu)
>>> 
>>>    for_each_cpu(sibling, cpu_sibling_mask(cpu))
>>>        cpumask_clear_cpu(cpu, cpu_sibling_mask(sibling));
>>> +    for_each_cpu(sibling, cpu_llc_shared_mask(cpu))
>>> +        cpumask_clear_cpu(cpu, cpu_llc_shared_mask(sibling));
>>> +    cpumask_clear(cpu_llc_shared_mask(cpu));
>>>    cpumask_clear(cpu_sibling_mask(cpu));
>>>    cpumask_clear(cpu_core_mask(cpu));
>>>    c->phys_proc_id = 0;
>> 
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