linux-kernel - Re: [PATCH] dmaengine: idxd: Check availability of workqueue allocated by idxd wq driver before using

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Message-ID: <0cf422b2-57ef-434a-b5b6-54e69f2d46c0@intel.com>
Date: Thu, 8 May 2025 17:49:06 -0700
From: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@...el.com>
To: Dave Jiang <dave.jiang@...el.com>, Yi Sun <yi.sun@...el.com>,
	<vinicius.gomes@...el.com>, <dmaengine@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: <gordon.jin@...el.com>
Subject: Re: [PATCH] dmaengine: idxd: Check availability of workqueue
 allocated by idxd wq driver before using


On 5/8/2025 5:07 PM, Dave Jiang wrote:
>
> On 5/8/25 5:03 PM, Yi Sun wrote:
>> Running IDXD workloads in a container with the /dev directory mounted can
>> trigger a call trace or even a kernel panic when the parent process of the
>> container is terminated.
>>
>> This issue occurs because, under certain configurations, Docker does not
>> properly propagate the mount replica back to the original mount point.
>>
>> In this case, when the user driver detaches, the WQ is destroyed but it
> I would be more specific. wq->wq (workqueue) that is allocated by the cdev user driver during ->probe() is destroyed when the driver is unbound.
>
>> still calls destroy_workqueue() attempting to completes all pending work.
>> It's necessary to check wq->wq and skip the drain if it no longer exists.
>>
>> Signed-off-by: Yi Sun <yi.sun@...el.com>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>
>
>> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
>> index ff94ee892339..a202fe4937a7 100644
>> --- a/drivers/dma/idxd/cdev.c
>> +++ b/drivers/dma/idxd/cdev.c
>> @@ -349,7 +349,9 @@ static void idxd_cdev_evl_drain_pasid(struct idxd_wq *wq, u32 pasid)
>>   			set_bit(h, evl->bmap);
>>   		h = (h + 1) % size;
>>   	}
>> -	drain_workqueue(wq->wq);
>> +	if (wq->wq)
>> +		drain_workqueue(wq->wq);
>> +
>>   	mutex_unlock(&evl->lock);
>>   }
>>