Subject: Re: USB modem triggers a DIAGNOSTIC message in ppp...
To: None <>
From: Brad Spencer <>
List: current-users
Date: 12/10/1999 19:25:29
   > 	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 -
[finger for PGP public key]