On Tue, Dec 15, 2009 at 11:31:32AM +0100, Peter Zijlstra wrote:
On Tue, 2009-12-15 at 19:40 +1100, Paul Mackerras wrote:It is quite legitimate for CPUs to be numbered sparsely, meaning thatCute, do you actually have hardware that does this?
it possible for an online CPU to have a number which is greater than
the total count of possible CPUs.
Currently find_get_context() has a sanity check on the cpu number
where it checks it against num_possible_cpus(). This test can fail
for a legitimate cpu number if the cpu_possible_mask is sparsely
populated.
This fixes the problem by checking the CPU number against
nr_cpumask_bits instead, since that is the appropriate check to ensure
that the cpu number is same to pass to cpu_isset() subsequently.
Yeah, Mikey ran across this on a POWER7 box here.