Re: Sporadious hang on 2.0.3[0,1,2,3,4pre2]

Alan Cox (
Thu, 5 Mar 1998 23:45:58 +0000 (GMT)

> I've been running 2.0.33+tcpdebug for 5 days until it crashed (sorry, I
> was in a hurry so I just rebooted the machine without inspecting it further).
> The machine locked up completely and filled the console with
> messages like:
> .... couldn't get a free skbuff ...
> .... couldn't get a free page ...
> There was no output from the debug-skbuff in the logs.

That one is a machine running totally out of memory. Would it be reasonable
to expect it to run out of memory ?

> Let's assume that at least my problem here is related to a defective
> skbuff list caused by some other kernel-code, maybe not even the networking-
> code. What about adding some kind of CRC to each skbuff head and walking
> down the whole list upon free_skb()/alloc_skb() (is it a list and is this
> possible?) and possibly on other frequently called places in the kernel,

Thats sort of what the tcp debug does. There is magic in each sk_buff which
is checked by all the low level sk_buff handlign routines.


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