From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will@kernel.org>
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>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Qais Yousef <qais.yousef@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>,
kernel-team@android.com
Subject: Re: [PATCH v3 00/14] An alternative series for asymmetric AArch32 systems
Date: Thu, 19 Nov 2020 17:11:27 +0100 [thread overview]
Message-ID: <20201119161127.GQ3121392@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201113093720.21106-1-will@kernel.org>
On Fri, Nov 13, 2020 at 09:37:05AM +0000, Will Deacon wrote:
> The aim of this series is to allow 32-bit ARM applications to run on
> arm64 SoCs where not all of the CPUs support the 32-bit instruction set.
>
> There are some major changes in v3:
>
> * Add some scheduler hooks for restricting a task's affinity mask
> * Implement these hooks for arm64 so that we can avoid 32-bit tasks
> running on 64-bit-only cores
> * Restrict affinity mask of 32-bit tasks on execve()
> * Prevent hot-unplug of all 32-bit CPUs if we have a mismatched system
> * Ensure 32-bit EL0 cpumask is zero-initialised (oops)
>
> It's worth mentioning that this approach goes directly against my
> initial proposal for punting the affinity management to userspace,
> because it turns out that doesn't really work. There are cases where the
> kernel has to muck with the affinity mask explicitly, such as execve(),
> CPU hotplug and cpuset balancing. Ensuring that these don't lead to
> random SIGKILLs as far as userspace is concerned means avoiding any
Mooo, I thought we were okay with that... Use does stupid, user gets
SIGKIL. What changed?
> 64-bit-only CPUs appearing in the affinity mask for a 32-bit task, at
> which point it's easier just to handle everything in the kernel anyway.
next prev parent reply other threads:[~2020-11-19 16:11 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 9:37 [PATCH v3 00/14] An alternative series for asymmetric AArch32 systems Will Deacon
2020-11-13 9:37 ` [PATCH v3 01/14] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon
2020-11-13 9:37 ` [PATCH v3 02/14] arm64: Allow mismatched 32-bit EL0 support Will Deacon
2020-11-19 11:27 ` Valentin Schneider
2020-11-19 13:12 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 03/14] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon
2020-11-13 9:37 ` [PATCH v3 04/14] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Will Deacon
2020-11-13 9:37 ` [PATCH v3 05/14] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2020-11-13 9:37 ` [PATCH v3 06/14] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2020-11-13 9:37 ` [PATCH v3 07/14] sched: Introduce restrict_cpus_allowed_ptr() to limit task CPU affinity Will Deacon
2020-11-19 9:18 ` Quentin Perret
2020-11-19 11:03 ` Quentin Perret
2020-11-19 11:05 ` Will Deacon
2020-11-19 11:27 ` Valentin Schneider
2020-11-19 13:13 ` Will Deacon
2020-11-19 14:54 ` Valentin Schneider
2020-11-19 16:41 ` Will Deacon
2020-11-19 12:47 ` Valentin Schneider
2020-11-19 13:13 ` Will Deacon
2020-11-19 14:54 ` Valentin Schneider
2020-11-19 16:09 ` Peter Zijlstra
2020-11-19 16:57 ` Valentin Schneider
2020-11-19 19:25 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 08/14] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2020-11-19 9:24 ` Quentin Perret
2020-11-19 11:06 ` Will Deacon
2020-11-19 16:19 ` Peter Zijlstra
2020-11-19 16:30 ` Will Deacon
2020-11-19 16:44 ` Peter Zijlstra
2020-11-19 16:51 ` Will Deacon
2020-11-19 16:14 ` Peter Zijlstra
2020-11-19 16:28 ` Will Deacon
2020-11-19 16:42 ` Peter Zijlstra
2020-11-19 16:48 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 09/14] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2020-11-19 9:29 ` Quentin Perret
2020-11-19 11:06 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 10/14] sched: Introduce arch_cpu_allowed_mask() to limit fallback rq selection Will Deacon
2020-11-19 9:38 ` Quentin Perret
2020-11-19 11:07 ` Will Deacon
2020-11-19 20:39 ` Will Deacon
2020-11-23 14:48 ` Quentin Perret
2020-11-13 9:37 ` [PATCH v3 11/14] sched: Reject CPU affinity changes based on arch_cpu_allowed_mask() Will Deacon
2020-11-19 9:47 ` Quentin Perret
2020-11-19 11:07 ` Will Deacon
2020-11-19 14:30 ` Quentin Perret
2020-11-19 16:44 ` Will Deacon
2020-11-13 9:37 ` [PATCH v3 12/14] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2020-11-13 9:37 ` [PATCH v3 13/14] arm64: Implement arch_cpu_allowed_mask() Will Deacon
2020-11-13 9:37 ` [PATCH v3 14/14] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2020-11-19 16:11 ` Peter Zijlstra [this message]
2020-11-19 16:39 ` [PATCH v3 00/14] An alternative series for asymmetric AArch32 systems Will Deacon
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