Bug#522785: linux-image-2.6.26-1-powerpc-smp: system unstable on SMP PowerPC 7455 (PowerMac G4) when high memory used (>768MB)

[Moritz Muehlenhoff <jmm@inutil.org>]

On Mon, Apr 06, 2009 at 08:51:19AM -0400, Branden Robinson wrote:
> Package: linux-image-2.6.26-1-powerpc-smp
> Version: 2.6.26-13
> Severity: normal
> 
> Howdy kernel team,
> 
> I've had this problem for years[1], on two different models of PowerMac, with
> multiple different sets of memory modules (because I was assured--wrongly, it
> seems--that I might have bad DIMMs).
> 
> I have 1GB of RAM but can only use 768MB of it because permitting the
> kernel to enable its highmem code for PowerPC causes grave instability.  On
> a modern kernel (2.6.26), I can't even get as far as the X server starting
> up.
> 
> (By instability, I mean various processes in the boot sequence report
> problems, including "Segmentation fault", "Aborted", and "malloc: assertion
> botched".  These results appear to be non-deterministic--different
> processes fail with each boot, but as memory pressure increases, the
> problems appear to increase in frequency.)
> 
> In an effort to help debug this, I recompiled the stock Debian kernel with
> CONFIG_DEBUG_HIGHMEM enabled, but sadly I don't see that much more got
> logged.

The next release of Debian (6.0, code name Squeeze) will be based
on 2.6.32. Please test the current 2.6.32 from unstable/testing and tell
us whether the problem persists. If so, we should report it upstream
to the kernel.org developers.

The 2.6.32 kernel is available from packages.debian.org and can
be installed in both Debian stable, testing and unstable
installations.

Thanks,
        Moritz