From: Pawel Moll <pawel.moll@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
Suzuki Poulose <Suzuki.Poulose@arm.com>,
Mark Rutland <Mark.Rutland@arm.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] bus: arm-ccn: Fix use of smp_processor_id() in preemptible context
Date: Wed, 04 Oct 2017 12:26:58 +0100 [thread overview]
Message-ID: <1507116418.3164.97.camel@arm.com> (raw)
In-Reply-To: <20171003171413.18592-2-marc.zyngier@arm.com>
On Tue, 2017-10-03 at 18:14 +0100, Marc Zyngier wrote:
> Booting a DEBUG_PREEMPT enabled kernel on a CCN-based system
> results in the following splat:
>
> [...]
> arm-ccn e8000000.ccn: No access to interrupts, using timer.
> BUG: using smp_processor_id() in preemptible [00000000] code:
> swapper/0/1
> caller is debug_smp_processor_id+0x1c/0x28
> CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.13.0 #6111
> Hardware name: AMD Seattle/Seattle, BIOS 17:08:23 Jun 26 2017
> Call trace:
> [<ffff000008089e78>] dump_backtrace+0x0/0x278
> [<ffff00000808a22c>] show_stack+0x24/0x30
> [<ffff000008bc3bc4>] dump_stack+0x8c/0xb0
> [<ffff00000852b534>] check_preemption_disabled+0xfc/0x100
> [<ffff00000852b554>] debug_smp_processor_id+0x1c/0x28
> [<ffff000008551bd8>] arm_ccn_probe+0x358/0x4f0
> [...]
>
> as we use smp_processor_id() in the wrong context.
>
> Turn this into a get_cpu()/put_cpu() that extends over the CPU
> hotplug
> registration, making sure that we don't race against a CPU down
> operation.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Pawel Moll <pawel.moll@arm.com>
I assume you'll get this merged yourself? Or do you want me to relay
the CCN one (I've got a couple of other small changes to the driver in
the queue).
Paweł
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next prev parent reply other threads:[~2017-10-04 11:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-03 17:14 [PATCH v2 0/2] bus: CCN/CCI: Fix use of smp_processor_id() Marc Zyngier
2017-10-03 17:14 ` [PATCH v2 1/2] bus: arm-ccn: Fix use of smp_processor_id() in preemptible context Marc Zyngier
2017-10-04 11:26 ` Pawel Moll [this message]
2017-10-04 12:32 ` Marc Zyngier
2017-10-04 12:33 ` Pawel Moll
2017-10-03 17:14 ` [PATCH v2 2/2] bus: arm-cci: " Marc Zyngier
2017-10-03 17:18 ` [PATCH v2 0/2] bus: CCN/CCI: Fix use of smp_processor_id() Mark Rutland
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