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From:   Peter Newman <peternewman@google.com>
Date:   Wed, 8 Mar 2023 11:30:21 +0100
Message-ID: <CALPaoCjP4Zx9-QUOJwZEQ_5acFhgkr+9TND3mqUvefQmgkbqCw@mail.gmail.com>
Subject: Re: [PATCH v2 07/18] x86/resctrl: Move CLOSID/RMID matching and
 setting to use helpers
To:     James Morse <james.morse@arm.com>
Cc:     Reinette Chatre <reinette.chatre@intel.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org, Fenghua Yu <fenghua.yu@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        H Peter Anvin <hpa@zytor.com>,
        Babu Moger <Babu.Moger@amd.com>,
        shameerali.kolothum.thodi@huawei.com,
        D Scott Phillips OS <scott@os.amperecomputing.com>,
        carl@os.amperecomputing.com, lcherian@marvell.com,
        bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com,
        xingxin.hx@openanolis.org, baolin.wang@linux.alibaba.com,
        Jamie Iles <quic_jiles@quicinc.com>,
        Xin Hao <xhao@linux.alibaba.com>
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Hi James,

On Mon, Mar 6, 2023 at 12:32=E2=80=AFPM James Morse <james.morse@arm.com> w=
rote:
> On 02/02/2023 23:47, Reinette Chatre wrote:
> > On 1/13/2023 9:54 AM, James Morse wrote:
> >> +    resctrl_arch_set_closid_rmid(tsk, rdtgrp->closid, rdtgrp->mon.rmi=
d);
> >
> > This does not use the intended closid when rdtgrp->type =3D=3D RDTMON_G=
ROUP.
>
> Yes, it should be rdtgrp->mon.parent->closid.
>
> rdtgroup_mkdir_mon() initialises them to be the same, I guess its Peter's=
 monitor-group
> rename that means this could get the wrong value?

I noticed this earlier. The next revision of my MON group rename patch
series updates rdtgrp->closid to that of the new parent so that for
MON groups, rdtgrp->closid =3D=3D rdtgrp->mon.parent->closid continues to
hold.

It looks like rdt_move_group_tasks() assumes this, as it always sets
t->closid to rdtgrp->closid.

-Peter