linux-kernel - Re: [PATCH] x86/resctrl: fix an imbalance in domain_remove

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Message-ID: <c8124e0b-4c6e-cce8-d38d-1bc2c8f4438e@intel.com>
Date:   Tue, 10 Dec 2019 12:15:03 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Qian Cai <cai@....pw>
Cc:     Ryan Chen <yu.chen.surf@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Fenghua Yu <fenghua.yu@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        John Stultz <john.stultz@...aro.org>, sboyd@...nel.org,
        Tony Luck <tony.luck@...el.com>, tj@...nel.org,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/resctrl: fix an imbalance in domain_remove_cpu

Hi Qian,

On 12/10/2019 11:08 AM, Qian Cai wrote:
> 
> 
>> On Dec 10, 2019, at 1:44 PM, Reinette Chatre <reinette.chatre@...el.com> wrote:
>>
>>
>> "A system that supports resource monitoring may have multiple resources
>> while not all of these resources are capable of monitoring. Monitoring
>> related state is initialized only for resources that are capable of
>> monitoring and correspondingly this state should subsequently only be
>> removed from these resources that are capable of monitoring.
>>
>> domain_add_cpu() calls domain_setup_mon_state() only when r->mon_capable
>> is true where it will initialize d->mbm_over. However,
>> domain_remove_cpu() calls cancel_delayed_work(&d->mbm_over) without
>> checking r->mon_capable resulting in an attempt to cancel d->mbm_over on
>> all resources, even those that never initialized d->mbm_over because
>> they are not capable of monitoring. Hence, it triggers a debugobjects
>> warning when offlining CPUs because those timer debugobjects are never
>> initialized.
>>
>> ODEBUG:..."
> 
> Looks better to me. Do you want me to send a v2 for it or you could update it for merging?
> 

Could you please send v2? I am not the one that provides final approval
for inclusion nor the one that will take care of merging afterwards.

Thank you very much

Reinette