Commit [517361]  Maximize  Restore  History

perf_event: Fix incorrect range check on cpu number

commit 0f624e7e5625f4c30c836b7a5decfe2553582391 upstream.

It is quite legitimate for CPUs to be numbered sparsely, meaning
that 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()

Reported-by: Michael Neuling <>
Signed-off-by: Paul Mackerras <>
Tested-by: Michael Neuling <>
Acked-by: Peter Zijlstra <>
LKML-Reference: <>
Signed-off-by: Ingo Molnar <>
Signed-off-by: Greg Kroah-Hartman <>

Paul Mackerras Paul Mackerras 2009-12-15

Greg Kroah-Hartman Greg Kroah-Hartman 2009-12-18

changed kernel/perf_event.c
kernel/perf_event.c Diff Switch to side-by-side view

Get latest updates about Open Source Projects, Conferences and News.

Sign up for the SourceForge newsletter:

JavaScript is required for this form.

No, thanks