Re: Crash soon after an alloc_skb failure in 2.6.16 and previous, swap disabled

["linux-os \(Dick Johnson\)" <linux-os@analogic.com>]

On Thu, 30 Mar 2006, Just Marc wrote:

> Hello,
>

> I'm running a few machines with swap turned off and am experiencing
> crashes when the system is extremely low on kernel memory.   So far the
> crashes observed are always inside the recv function of the Ethernet
[SNIPPED...]

Huh? If no buffers are available, received packets get thrown on the
floor. I see the failure(s) happened in an interrupt. If so, the
problem is in the network driver and your starved memory situation
brought out a bug.

>
> The benefits of running a system without swap are arguable, but in my
> particular scenario I prefer to have connections dropped rather than
> experience the overheads and latencies of a heavily swapping system.

I read this as; "I want the advantages of swap, but I don't want
to use swap." Or, "It doesn't work as I expected so therefore it's
broken!" In any event, swap is used to handle the problems with a
finite amount of memory. Normally sleeping tasks get swapped out,
freeing their memory for your network stuff. If you don't have swap,
that memory can't be freed. Tough! You did it, so you live with
it -- but contact the maintainer of your network card. You may
have forced a bug to come to the surface.


Cheers,
Dick Johnson
Penguin : Linux version 2.6.15.4 on an i686 machine (5589.42 BogoMips).
Warning : 98.36% of all statistics are fiction, book release in April.
_


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