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

From: H. Peter Anvin
Date: Tue Sep 09 2014 - 03:42:27 EST


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@xxxxxxxxxxxxxxx> 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@xxxxxx>
>>> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>>> Tested-by: Linn Crosetto <linn@xxxxxx>
>>> Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx>
>>> ---
>>> 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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