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Subject[PATCH v8 0/2] x86/apic: x2apic write eoi msr notrace
Date
 RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
no locks held by swapper/1/0.

do_trace_write_msr
native_write_msr
native_apic_msr_eoi_write
smp_reschedule_interrupt
reschedule_interrupt

Reschedule interrupt may be called in CPU idle state. This causes lockdep
check warning above.

As Peterz pointed out:

| The thing is, many many smp_reschedule_interrupt() invocations don't
| actually execute anything much at all and are only sent to tickle the
| return to user path (which does the actual preemption).
|
| Having to do the whole irq_enter/irq_exit dance just for this unlikely
| debug case totally blows.

This patchset adds x2apic write eoi msr notrace to avoid the debug codes
splash and reverts irq_enter/irq_exit dance to avoid to make a very frequent
interrupt slower because of debug code.

v7 -> v8:
* cleanup patch 2/2 descriptions

v6 -> v7:
* cleanup storage class should be at the beginning of the declaration

v5 -> v6:
* split the patch
* don't duplicate the inline asm

v4 -> v5:
* add notrace mark

v3 -> v4:
* add notrace mark

v2 -> v3:
* revert irq_enter/irq_exit() since it is merged

v1 -> v2:
* add write msr notrace to avoid debug codes splash instead of slowdown
a very frequent interrupt


Wanpeng Li (2):
x86/msr: Add write msr notrace
x86/apic: x2apic write eoi msr notrace

arch/x86/include/asm/apic.h | 3 ++-
arch/x86/include/asm/msr.h | 14 +++++++++++++-
arch/x86/kernel/apic/apic.c | 1 +
arch/x86/kernel/kvm.c | 4 ++--
arch/x86/kernel/smp.c | 2 --
5 files changed, 18 insertions(+), 6 deletions(-)

--
1.9.1

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