linux-kernel - Re: [PATCH] firewire: fw-ohci: plug dma memory leak in AR handler

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Message-Id: <200803261737.30717.jwilson@redhat.com>
Date:	Wed, 26 Mar 2008 17:37:30 -0400
From:	Jarod Wilson <jwilson@...hat.com>
To:	linux1394-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firewire: fw-ohci: plug dma memory leak in AR handler

On Tuesday 25 March 2008 04:47:16 pm Jarod Wilson wrote:
> There's a nasty memory leak in firewire-ohci's ar_context_tasklet(), in
> that we're not freeing up some of the memory we use for each ar_buffer, due
> to a moving pointer. The problem has been there for a while, but didn't
> start to be noticed until we were doing a coherent allocation for the
> ar_buffer -- meaning we have a smaller pool of memory to work with now, so
> the problem crops up sooner. The manifestation of this comes after doing a
> bunch of I/O to a firewire disk, which eventually stalls, and this starts
> spewing to the console:
>
> PCI-DMA: Out of IOMMU space for 53248 bytes at device 0000:04:09.0
>
> The device there is one of my FireWire controllers trying to do I/O. The
> host is a fairly new rev. opteron.
>
> Just need to make sure we're freeing the correct memory range is pass
> through ar_context_tasklet to fix it. Probably something we ought to sneak
> into 2.6.25 if its still doable...

So as it turns out, while this is indeed a leak that needs to be plugged, it 
does NOT remedy the 'out of iommu space' issue, it just delays it a while 
longer. Still working on tracing the root cause of the memory exhaustion.


-- 
Jarod Wilson
jwilson@...hat.com
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