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

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Message-ID: <CAHtARFFNj1XD6PFnquNRdt6xwK6pKygH3YibSjLoT_u=P=yceA@mail.gmail.com>
Date:	Mon, 19 Sep 2011 12:26:00 -0700
From:	adam radford <aradford@...il.com>
To:	James Bottomley <James.Bottomley@...senpartnership.com>
Cc:	Chris Boot <bootc@...tc.net>,
	"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 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
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