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On 5/18/26 10:38 AM, Aboorva Devarajan wrote: > pnv_kexec_wait_secondaries_down() calls get_cpu() to obtain the current > CPU id but never calls the matching put_cpu(), leaking one > preempt_disable() nesting level on every invocation. > > In practice the imbalance does not trigger a visible splat because the > kexec teardown path is a one-way trip: IRQs are already disabled, no > schedule() occurs after the leak, and default_machine_kexec() overwrites > preempt_count with HARDIRQ_OFFSET before jumping into kexec_sequence() > which never returns. However the bookkeeping is still wrong. > > In the kexec teardown path IRQs are already disabled and the CPU is > pinned, so get_cpu()'s preempt_disable() side-effect is unnecessary. > Replace get_cpu() with raw_smp_processor_id() which returns the CPU id > without touching preempt_count. > > Fixes: 298b34d7d578 ("powerpc/powernv: Fix kexec races going back to OPAL") > Signed-off-by: Aboorva Devarajan > --- > arch/powerpc/platforms/powernv/setup.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c > index 4dbb47ddbdcc4..177da0defcb36 100644 > --- a/arch/powerpc/platforms/powernv/setup.c > +++ b/arch/powerpc/platforms/powernv/setup.c > @@ -396,7 +396,7 @@ static void pnv_kexec_wait_secondaries_down(void) > { > int my_cpu, i, notified = -1; > > - my_cpu = get_cpu(); > + my_cpu = raw_smp_processor_id(); > Is it always with irq-disabled? How about !CONFIG_SMP and in kexec_prepare_cpus. I see it disables interrupt later. (though it is a less common config) So use smp_processor_id()?? One could compile with CONFIG_DEBUG_PREEMPT=y and see any reports. > for_each_online_cpu(i) { > uint8_t status;