From: Jens Axboe <axboe@kernel.dk>
To: Christian Borntraeger <borntraeger@de.ibm.com>,
Ming Lei <ming.lei@redhat.com>,
linux-block@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@infradead.org>,
"jianchao . wang" <jianchao.w.wang@oracle.com>,
Stefan Haberland <sth@linux.vnet.ibm.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 2/2] blk-mq: convert WARN_ON in __blk_mq_run_hw_queue to printk
Date: Wed, 17 Jan 2018 09:07:44 -0700 [thread overview]
Message-ID: <8b86704f-24cd-fddb-c9ca-60263bee4174@kernel.dk> (raw)
In-Reply-To: <e8acbff6-3263-e4e9-0a5c-025d999a6134@de.ibm.com>
On 1/17/18 9:05 AM, Christian Borntraeger wrote:
>
>
> On 01/17/2018 04:46 PM, Jens Axboe wrote:
>> On 1/17/18 5:34 AM, Ming Lei wrote:
>>> We know this WARN_ON is harmless and the stack trace isn't useful too,
>>> so convert it to printk(), and avoid to confuse people.
>>
>> I disagree, it is useful to know the exact path it happened from,
>> in case it's a valid warning. It could be an inline run and
>> we screwed up the logic, or it could be from a workqueue and
>> the reason would be entirely different.
>
> Then add a dump_stack or whatever, but WARN_ON does have fatal effects
> for some setups. If it can happen then WARN_ON is just wrong.
dump_stack() is fine - and the intent is for it to never happen, it
would be nice to close those holes so we're only catching cases that
are due to bad code.
--
Jens Axboe
next prev parent reply other threads:[~2018-01-17 16:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-17 12:34 [PATCH 0/2] blk-mq: two patches related with CPU hotplug Ming Lei
2018-01-17 12:34 ` [PATCH 1/2] blk-mq: make sure hctx->next_cpu is set correctly Ming Lei
2018-01-17 15:45 ` Jens Axboe
2018-01-17 16:14 ` Ming Lei
2018-01-17 12:34 ` [PATCH 2/2] blk-mq: convert WARN_ON in __blk_mq_run_hw_queue to printk Ming Lei
2018-01-17 15:46 ` Jens Axboe
2018-01-17 16:05 ` Christian Borntraeger
2018-01-17 16:07 ` Jens Axboe [this message]
2018-01-17 16:17 ` Ming Lei
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