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SubjectRe: WARNING: CPU: 0 PID: 0 at drivers/irqchip/irq-gic-v3-its.c
On 09/11/18 17:28, Sudeep Holla wrote:
> On Fri, Nov 9, 2018 at 4:10 PM Marc Zyngier <> wrote:
> [...]
>> See bb42ca474010 and d003d029cea8 for details.
>> Now, activating this workaround leads to lockdep being really angry,
>> most likely because the cpus_read_lock is not taken, which is a change
>> in behaviour...
>> I'm trying to dig into this now.
> Yes we found similar issue in kernel/sched/core.c sched_init_smp
> There's a fix with detailed description in -next
> (Commit 40fa3780bac2 ("sched/core: Take the hotplug lock in sched_init_smp()")
> The behaviour changed since commit cb538267ea1e ("jump_label/lockdep:
> Assert we hold the hotplug lock for _cpuslocked() operations")

I indeed came to the same conclusion, but the fix is slightly less than
obvious. I have the following arm64-specific crap, but it is pretty

diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
index f258636273c9..9e96e9eaca9b 100644
--- a/arch/arm64/kernel/time.c
+++ b/arch/arm64/kernel/time.c
@@ -36,6 +36,7 @@
#include <linux/clocksource.h>
#include <linux/clk-provider.h>
#include <linux/acpi.h>
+#include <linux/cpu.h>

#include <clocksource/arm_arch_timer.h>

@@ -69,7 +70,9 @@ void __init time_init(void)
u32 arch_timer_rate;

+ cpus_read_lock();
+ cpus_read_unlock();


Qian, can you please let me know if this helps? If it does, we'll have
to think of something a bit better...

Jazz is not dead. It just smells funny...

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