Fw: 2.6.15-rc2-mm1 problems (get_cpu / NUMA optimizations)
laforge at netfilter.org
Thu Nov 24 21:58:28 CET 2005
On Wed, Nov 23, 2005 at 03:56:03PM -0800, David S. Miller wrote:
> I've seen this reported multiple times.
> It seems that module load is attempted by IP-tables while
> some locks are held, or similar.
yes, this was introduced by the recent NUMA patches that introduced
get_cpu() / put_cpu() all over the place.
Seems like I only now realize the implications that this has all over
the code, and to be honest, I'm not confident that there is a short-term
fix since a lot of code needs to be audited.
Also, apart from just the iptables core, we actually call the
checkentry() and destroy() functions of the match/target extensions
under get_cpu() now. Plugin authors always assumed that they'd be able
to do stuff like kmalloc(GFP_KERNEL) since they are guaranteed to always
only be called from userspace context under the ipt_mutex.
I'm further analyzing our options, but we might have to pull out that
NUMA change, especially since I'm heading for FOSS.in/linux-bangalore in
a couple of days.
- Harald Welte <laforge at netfilter.org> http://netfilter.org/
"Fragmentation is like classful addressing -- an interesting early
architectural error that shows how much experimentation was going
on while IP was being designed." -- Paul Vixie
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