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

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Message-Id: <35666437-F8AF-4170-A00F-79C34370BEF0@lca.pw>
Date:   Tue, 10 Dec 2019 14:08:38 -0500
From:   Qian Cai <cai@....pw>
To:     Reinette Chatre <reinette.chatre@...el.com>
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



> 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?