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From: Marc Zyngier <maz@kernel.org>
To: John Garry <john.garry@huawei.com>
Cc: Ming Lei <tom.leiming@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	linux-block <linux-block@vger.kernel.org>,
	Bart Van Assche <bvanassche@acm.org>,
	Hannes Reinecke <hare@suse.com>, Christoph Hellwig <hch@lst.de>,
	"chenxiang (M)" <chenxiang66@hisilicon.com>,
	Keith Busch <kbusch@kernel.org>,
	"liudongdong (C)" <liudongdong3@huawei.com>,
	wanghuiqiang <wanghuiqiang@huawei.com>,
	"Wangzhou (B)" <wangzhou1@hisilicon.com>
Subject: Re: [PATCH V5 0/6] blk-mq: improvement CPU hotplug
Date: Wed, 05 Feb 2020 14:23:38 +0000	[thread overview]
Message-ID: <19e798801684f952e7237240ca3b43f0@kernel.org> (raw)
In-Reply-To: <c8a31bf9-7e25-aff1-e0df-7d9106324b9f@huawei.com>

On 2020-02-05 14:08, John Garry wrote:
> On 03/02/2020 18:16, John Garry wrote:
>> On 03/02/2020 15:43, Marc Zyngier wrote:
>>> On 2020-02-03 12:56, John Garry wrote:
>>> 
>>> [...]
>>> 
>>>>> Can you trigger it after disabling irqbalance?
>>>> 
>>>> No, so tested by killing the irqbalance process and it ran for 25
>>>> minutes without issue.
>>> 
>>> OK, that's interesting.
>>> 
>>> Can you find you whether irqbalance tries to move an interrupt to an 
>>> offlined CPU?
>>> Just putting a trace into git_set_affinity() should be enough.
>>> 
>> 
> 
> Just an update here: I have tried this same test on a new model dev
> board and I don't experience the same issue. It's quite stable.

Is it the exact same SoC? Or a revised version?

> I'd like to get to the bottom of the issue reported, but I feel that
> the root cause may be a BIOS issue and I will get next to no BIOS
> support for that particular board. Hmmm.

I'd very much like to understand it too. Your latest log is even more 
puzzling,
as the backtrace shows a switch_to() even earlier... The fact that this 
only
happens on hotplug off tends to tell me that the firmware gets confused 
with
PSCI OFF. You'd see something like that if a CPU was taken into the 
firmware
(or powered-off) without the rest of the kernel knowing...

Could it be that PSCI powers off more than a single CPU at once?

         M.
-- 
Jazz is not dead. It just smells funny...

  reply	other threads:[~2020-02-05 14:23 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15 11:44 [PATCH V5 0/6] blk-mq: improvement CPU hotplug Ming Lei
2020-01-15 11:44 ` [PATCH 1/6] blk-mq: add new state of BLK_MQ_S_INACTIVE Ming Lei
2020-01-15 11:44 ` [PATCH 2/6] blk-mq: prepare for draining IO when hctx's all CPUs are offline Ming Lei
2020-01-15 11:44 ` [PATCH 3/6] blk-mq: stop to handle IO and drain IO before hctx becomes inactive Ming Lei
2020-01-15 11:44 ` [PATCH 4/6] blk-mq: re-submit IO in case that hctx is inactive Ming Lei
2020-01-15 11:44 ` [PATCH 5/6] blk-mq: handle requests dispatched from IO scheduler in case of inactive hctx Ming Lei
2020-01-15 11:44 ` [PATCH 6/6] block: deactivate hctx when all its CPUs are offline when running queue Ming Lei
2020-01-15 17:00 ` [PATCH V5 0/6] blk-mq: improvement CPU hotplug John Garry
2020-01-20 13:23   ` John Garry
2020-01-31 10:04     ` Ming Lei
2020-01-31 10:24       ` John Garry
2020-01-31 10:58         ` Ming Lei
2020-01-31 17:51           ` John Garry
2020-01-31 18:02             ` John Garry
2020-02-01  1:31               ` Ming Lei
2020-02-01 11:05                 ` Marc Zyngier
2020-02-01 11:31                   ` Thomas Gleixner
2020-02-03 10:30                     ` John Garry
2020-02-03 10:49                       ` John Garry
2020-02-03 10:59                         ` Ming Lei
2020-02-03 12:56                           ` John Garry
2020-02-03 15:43                             ` Marc Zyngier
2020-02-03 18:16                               ` John Garry
2020-02-05 14:08                                 ` John Garry
2020-02-05 14:23                                   ` Marc Zyngier [this message]
2020-02-07 10:56           ` John Garry

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