linux-kernel - Re: [PATCH v2] x86, hotplug: fix llc shared map unreleased during cpu hotplug

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Message-ID: <20140729070626.GA9635@kernel>
Date:	Tue, 29 Jul 2014 15:06:26 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc:	hpa@...or.com, Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
	Borislav Petkov <bp@...en8.de>,
	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>, linux-kernel@...r.kernel.org,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	"Zhang, Yang Z" <yang.z.zhang@...el.com>,
	Yong Wang <yong.y.wang@...ux.intel.com>
Subject: Re: [PATCH v2] x86, hotplug: fix llc shared map unreleased during
 cpu hotplug

Hi Yasuaki,
On Wed, Jul 23, 2014 at 05:56:07PM +0900, Yasuaki Ishimatsu wrote:
>(2014/07/22 17:04), Wanpeng Li wrote:
>> [  220.262093] BUG: unable to handle kernel NULL pointer dereference at 0000000000000004
>> [  220.262104] IP: [<ffffffff810e7ac9>] find_busiest_group+0x2b9/0xa30
>> [  220.262111] PGD 5a9d5067 PUD 13067 PMD 0
>> [  220.262117] Oops: 0000 [#3] SMP
>> [...]
>> [  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
>> [  220.262366]  [<ffffffff812292fd>] sysfs_write_file+0xdd/0x160
>> [  220.262377]  [<ffffffff811b7e78>] vfs_write+0xc8/0x170
>> [  220.262384]  [<ffffffff811b83ca>] SyS_write+0x5a/0xa0
>> [  220.262388]  [<ffffffff816f76b9>] system_call_fastpath+0x16/0x1b
>> 
>> 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.
>> 
>
>I posted a latest patch as follows:
>https://lkml.org/lkml/2014/7/22/1018
>
>Could you confirm the patch fixes your issue?

Sorry for the late, there is still call trace w/ your patch applied. The
call trace is in attachment.

Regards,
Wanpeng Li 

>
>Thanks,
>Yasuaki Ishimatsu
>
>> Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
>> ---
>> 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;
>> 
>

View attachment "call trace.txt" of type "text/plain" (13980 bytes)