device driver memory leak in 5.1-20030726?

Gary Jennejohn garyj at
Mon Jul 28 03:58:51 PDT 2003

John-Mark Gurney writes:
> --E/DnYTRukya0zdZ1
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> Lukas Ertl wrote this message on Mon, Jul 28, 2003 at 01:11 +0200:
> > Then I have no explanation.  I'm running the box with a WiFi card,
> > generating lots of network traffic, and the box is running fine, no
> > panics, and low devbuf allocation.  I'm running the box with the USB
> > Bluetooth dongle, generating much less traffic (it's just a 9.6kbit GSM
> > link), and the box panics within half an hour in kmem_malloc, with devbuf
> > allocation up to 74MB.  It must be either in the Bluetooth code or in the
> > USB code.
> Upon futher looking at the code, I have a better fix for this.  Let me
> know how things go for you.

It appears to me that the test in usb_block_allocmem() should be
(p->tag->parent == tag || p->tag->parent == tag->parent) and NOT
p->tag == tag! That's because bus_dma_tag_create() uses the tag
passed into usb_block_allocmem() as newtag->parent!

Unfortunately, bus_dma_tag is an opaque type and there's no way to
access the parent member anywhere but in the MD busdma_machdep.c :-(

Anyway, as written there's no way that I can see that the code can
work correctly.

Gary Jennejohn / garyj[at] gj[at] gj[at]

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