Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 07/26] hw_breakpoint: Use cpu_possible_mask in {reserve,release}_bp_slot() | Date | Mon, 1 Jul 2013 13:10:02 -0700 |
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3.9-stable review patch. If anyone has any objections, please let me know.
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From: Oleg Nesterov <oleg@redhat.com>
commit c790b0ad23f427c7522ffed264706238c57c007e upstream.
fetch_bp_busy_slots() and toggle_bp_slot() use for_each_online_cpu(), this is obviously wrong wrt cpu_up() or cpu_down(), we can over/under account the per-cpu numbers.
For example:
# echo 0 >> /sys/devices/system/cpu/cpu1/online # perf record -e mem:0x10 -p 1 & # echo 1 >> /sys/devices/system/cpu/cpu1/online # perf record -e mem:0x10,mem:0x10,mem:0x10,mem:0x10 -C1 -a & # taskset -p 0x2 1
triggers the same WARN_ONCE("Can't find any breakpoint slot") in arch_install_hw_breakpoint().
Reported-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20130620155009.GA6327@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/events/hw_breakpoint.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -149,7 +149,7 @@ fetch_bp_busy_slots(struct bp_busy_slots return; } - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { unsigned int nr; nr = per_cpu(nr_cpu_bp_pinned[type], cpu); @@ -235,7 +235,7 @@ toggle_bp_slot(struct perf_event *bp, bo if (cpu >= 0) { toggle_bp_task_slot(bp, cpu, enable, type, weight); } else { - for_each_online_cpu(cpu) + for_each_possible_cpu(cpu) toggle_bp_task_slot(bp, cpu, enable, type, weight); }
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