linux-kernel - Re: iommu_iova leak [inside 3w-9xxx]

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Date:	Mon, 19 Sep 2011 21:54:27 +0100
From:	Chris Boot <bootc@...tc.net>
To:	adam radford <aradford@...il.com>
CC:	James Bottomley <James.Bottomley@...senpartnership.com>,
	"Woodhouse, David" <david.woodhouse@...el.com>,
	lkml <linux-kernel@...r.kernel.org>,
	Adam Radford <linuxraid@....com>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>
Subject: Re: iommu_iova leak [inside 3w-9xxx]

On 19/09/2011 20:26, adam radford wrote:
> On Sun, Sep 18, 2011 at 7:56 AM, James Bottomley
> <James.Bottomley@...senpartnership.com>  wrote:
>> On Sun, 2011-09-18 at 18:25 +0400, James Bottomley wrote:
>>> On Sun, 2011-09-18 at 15:05 +0100, Chris Boot wrote:
>>>>> Hardly ... all it's saying is that twa_exit doesn't wait for pending I/O
>>>>> to complete, so when you remove the module it tears down in the middle
>>>>> of an I/O.  A bug, yes, but it's not indicative of any sort of leak in
>>>>> the maps/unmaps.
>>>>
>>>> James,
>>>>
>>>> I don't think that's the case - I had unmounted all filesystems, deactivated all volume groups, and performed a sync before waiting a few seconds and running rmmod. Next time I'll also 'echo 1>  /sys/block/sdX/device/delete' if that's helpful.
>>> Actually, I take all that back: the driver has a bug in QUEUE_FULL
>>> handling: twa_scsi_queue() calls twa_scsiop_execute_scsi(), which maps
>>> the dma buffer, but if the card responds QUEUE_FULL it just returns
>>> SCSI_MLQUEUE_HOST_BUSY without ever unmapping.  That leg in the code
>>> frees the request but also doesn't unmap it.  In fact any error return
>>> from twa_scsiop_execute_scsi() seems to have the same problem (but
>>> QUEUE_FULL is the only silent one).
>>>
>>> I trust Adam will fix this.
>> Actually, while Adam's mulling this, try the following.  It should at
>> least confirm we're on the right track.
>>
>> James
>>
>> ---
>>
>> diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c
>> index b7bd5b0..3868ab2 100644
>> --- a/drivers/scsi/3w-9xxx.c
>> +++ b/drivers/scsi/3w-9xxx.c
>> @@ -1800,10 +1800,12 @@ static int twa_scsi_queue_lck(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_
>>         switch (retval) {
>>         case SCSI_MLQUEUE_HOST_BUSY:
>>                 twa_free_request_id(tw_dev, request_id);
>> +               twa_unmap_scsi_data(tw_dev, request_id);
>>                 break;
>>         case 1:
>>                 tw_dev->state[request_id] = TW_S_COMPLETED;
>>                 twa_free_request_id(tw_dev, request_id);
>> +               twa_unmap_scsi_data(tw_dev, request_id);
>>                 SCpnt->result = (DID_ERROR<<  16);
>>                 done(SCpnt);
>>                 retval = 0;
>>
>>
>>
> James,
>
> Your patch looks correct.
>
> Acked-by: Adam Radford<aradford@...il.com>
>
> -Adam

Reported-by: Chris Boot <bootc@...tc.net>
Tested-by: Chris Boot <bootc@...tc.net>

-- 
Chris Boot
bootc@...tc.net

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