Subject: Re: USB modem triggers a DIAGNOSTIC message in ppp...
To: Brad Spencer <email@example.com>
From: Lennart Augustsson <firstname.lastname@example.org>
Date: 12/11/1999 17:40:37
I thought I had eliminated the allocation from interrupt context, but I'll look at
Brad Spencer wrote:
> > usb_block_allocmem: in interrupt context, size=4096
> > Having no real idea what this message is trying to get at, I was wondering
> > if anyone knows what this means??
> The kernel malloc may have to block while waiting for pages to become
> available. This is not a good thing to do in an interrupt context ;-)
> So, if you can use kgdb or ddb: just set a breakpoint on that diagnostic
> message, trigger it and post a stack backtrace, showing where
> usb_block_allocmem is called from.
> Ok... I set a breakpoint with ddb and the following stack trace was
> returned [1.4L kernel]:
> _usb_block_allocmem(f026dcc4,1000,0,f0568c3c,f0460000) at _usb_block_allocmem + 0x15
> _usb_allocmem(f0460000,29b,0,f0568c3c,f4e62bdc) at _usb_allocmem + 0x39
> _uhci_allocm(f0460000,f0568c3c,29b,e000de42,f4c34390) at _usb_allocm + 0x13
> _usbd_transfer(f056800) at _usbd_transfer + 0x52
> _umodemstart(f4c34390) at _umodemstart + 0xd0
> _pppstart(f4c34390) at _pppstart + 0x1b
> _pppsyncstart(f02908cc) at _pppsyncstart + 0x484
> _pppintr(10,10,f4e1bdc8,f4e1bdc8,f4e62ed4) at _pppintr + 0x89
> [ddb complained about corruption at this point]
> I could not make the system panic from ddb, so I do not have a kernel core
> dump to verify the above which was copied on to paper and then into email.
> Brad Spencer - email@example.com http://anduin.eldar.org
> [finger firstname.lastname@example.org for PGP public key]