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From: Will Deacon <will@kernel.org>
To: Qais Yousef <qais.yousef@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Quentin Perret <qperret@google.com>, Tejun Heo <tj@kernel.org>,
	Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	kernel-team@android.com
Subject: Re: [PATCH v6 07/21] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1
Date: Mon, 24 May 2021 21:21:32 +0100	[thread overview]
Message-ID: <20210524202131.GB15545@willie-the-truck> (raw)
In-Reply-To: <20210521173934.pjcv37j63odtsrp6@e107158-lin.cambridge.arm.com>

Hi Qais,

On Fri, May 21, 2021 at 06:39:34PM +0100, Qais Yousef wrote:
> On 05/18/21 10:47, Will Deacon wrote:
> > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> > index a945504c0ae7..8c799260a4a2 100644
> > --- a/kernel/cgroup/cpuset.c
> > +++ b/kernel/cgroup/cpuset.c
> > @@ -3322,9 +3322,17 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
> >  
> >  void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
> >  {
> > +	const struct cpumask *cs_mask;
> > +	const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
> > +
> >  	rcu_read_lock();
> > -	do_set_cpus_allowed(tsk, is_in_v2_mode() ?
> > -		task_cs(tsk)->cpus_allowed : cpu_possible_mask);
> > +	cs_mask = task_cs(tsk)->cpus_allowed;
> > +
> > +	if (!is_in_v2_mode() || !cpumask_subset(cs_mask, possible_mask))
> > +		goto unlock; /* select_fallback_rq will try harder */
> > +
> > +	do_set_cpus_allowed(tsk, cs_mask);
> 
> Shouldn't we take the intersection with possible_mask like we discussed before?
> 
> 	https://lore.kernel.org/lkml/20201217145954.GA17881@willie-the-truck/

Yes, and that's what the '!cpumask_subset()' check is doing above. Either
we use the valid subset of the cpuset mask (which is the intersection with
the possible mask) or we bail if that set is empty.

Will

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  reply	other threads:[~2021-05-25  2:05 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-18  9:47 [PATCH v6 00/21] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-05-18  9:47 ` [PATCH v6 01/21] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon
2021-05-21 10:47   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 02/21] arm64: Allow mismatched 32-bit EL0 support Will Deacon
2021-05-21 10:25   ` Catalin Marinas
2021-05-24 12:05     ` Will Deacon
2021-05-24 13:49       ` Catalin Marinas
2021-05-21 10:41   ` Catalin Marinas
2021-05-24 12:09     ` Will Deacon
2021-05-24 13:46       ` Catalin Marinas
2021-05-21 15:22   ` Qais Yousef
2021-05-24 20:21     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 03/21] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon
2021-05-21 10:47   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 04/21] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Will Deacon
2021-05-21 10:55   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 05/21] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2021-05-21 11:00   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 06/21] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2021-05-21 16:03   ` Peter Zijlstra
2021-05-24 12:17     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 07/21] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2021-05-21 17:39   ` Qais Yousef
2021-05-24 20:21     ` Will Deacon [this message]
2021-05-18  9:47 ` [PATCH v6 08/21] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Will Deacon
2021-05-21 16:25   ` Qais Yousef
2021-05-24 21:09     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 09/21] sched: Reject CPU affinity changes based on task_cpu_possible_mask() Will Deacon
2021-05-18  9:47 ` [PATCH v6 10/21] sched: Introduce task_struct::user_cpus_ptr to track requested affinity Will Deacon
2021-05-18  9:47 ` [PATCH v6 11/21] sched: Split the guts of sched_setaffinity() into a helper function Will Deacon
2021-05-21 16:41   ` Qais Yousef
2021-05-24 21:16     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 12/21] sched: Allow task CPU affinity to be restricted on asymmetric systems Will Deacon
2021-05-21 17:11   ` Qais Yousef
2021-05-24 21:43     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 13/21] sched: Admit forcefully-affined tasks into SCHED_DEADLINE Will Deacon
2021-05-18 10:20   ` Quentin Perret
2021-05-18 10:28     ` Will Deacon
2021-05-18 10:48       ` Quentin Perret
2021-05-18 10:59         ` Will Deacon
2021-05-18 13:19           ` Quentin Perret
2021-05-20  9:13             ` Juri Lelli
2021-05-20 10:16               ` Will Deacon
2021-05-20 10:33                 ` Quentin Perret
2021-05-20 12:38                   ` Juri Lelli
2021-05-20 12:38                   ` Daniel Bristot de Oliveira
2021-05-20 15:06                     ` Dietmar Eggemann
2021-05-20 16:00                       ` Daniel Bristot de Oliveira
2021-05-20 17:55                         ` Dietmar Eggemann
2021-05-20 18:03                           ` Will Deacon
2021-05-21 11:26                             ` Dietmar Eggemann
2021-05-20 18:01                     ` Will Deacon
2021-05-21  5:25                       ` Juri Lelli
2021-05-21  8:15                         ` Quentin Perret
2021-05-21  8:39                           ` Juri Lelli
2021-05-21 10:37                             ` Will Deacon
2021-05-21 11:23                               ` Dietmar Eggemann
2021-05-21 13:02                                 ` Quentin Perret
2021-05-21 14:04                                   ` Juri Lelli
2021-05-21 17:47                                     ` Dietmar Eggemann
2021-05-21 13:00                               ` Daniel Bristot de Oliveira
2021-05-21 13:12                                 ` Quentin Perret
2021-05-24 20:47                                 ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 14/21] freezer: Add frozen_or_skipped() helper function Will Deacon
2021-05-18  9:47 ` [PATCH v6 15/21] sched: Defer wakeup in ttwu() for unschedulable frozen tasks Will Deacon
2021-05-18  9:47 ` [PATCH v6 16/21] arm64: Implement task_cpu_possible_mask() Will Deacon
2021-05-24 14:57   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 17/21] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2021-05-24 15:02   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 18/21] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2021-05-24 15:46   ` Catalin Marinas
2021-05-24 20:32     ` Will Deacon
2021-05-25  9:43       ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 19/21] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2021-05-24 15:47   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 20/21] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2021-05-24 15:47   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 21/21] Documentation: arm64: describe asymmetric 32-bit support Will Deacon
2021-05-21 17:37   ` Qais Yousef
2021-05-24 21:46     ` Will Deacon
2021-05-24 16:22   ` Catalin Marinas
2021-05-21 17:45 ` [PATCH v6 00/21] Add support for 32-bit tasks on asymmetric AArch32 systems Qais Yousef
2021-05-24 22:08   ` Will Deacon

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