On 23/08/12 04:23, Frederic Weisbecker wrote:

In the old times, the whole idle task was considered
as an RCU quiescent state. But as RCU became more and
more successful overtime, some RCU read side critical
section have been added even in the code of some
architectures idle tasks, for tracing for example.

Fantastic!  It fixes RCU CPU stalls that we were seeing on the SMP
kernel when built for generic Alpha.

A build of glibc and running its test suite reliably triggers RCU CPU
stalls when running a kernel built for generic Alpha.  I have just built
glibc and ran its test suite twice with no RCU CPU stalls with this
patch against a 3.5.2 kernel!  Nice.  Very nice.

I see the stable queue is CCed but I note the patch does not apply
cleanly to the 3.2.y kernel.  It would be nice to have a backport of the
patches for the 3.2 stable kernel.

So feel free to add:

Tested-by:  Michael Cree <redacted>

Cheers
Michael.