* Wanpeng Li <kernel...@gmail.com> wrote:
> ===============================
> [ INFO: suspicious RCU usage. ]
> 4.8.0+ #24 Not tainted
> -------------------------------
> ./arch/x86/include/asm/msr-trace.h:47 suspicious rcu_dereference_check()
> usage!
>
> other info that might help us debug this:
>
> 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.
>
> [<ffffffff9d492b95>] do_trace_write_msr+0x135/0x140
> [<ffffffff9d06f860>] native_write_msr+0x20/0x30
> [<ffffffff9d065fad>] native_apic_msr_eoi_write+0x1d/0x30
> [<ffffffff9d05bd1d>] smp_reschedule_interrupt+0x1d/0x30
> [<ffffffff9d8daec6>] reschedule_interrupt+0x96/0xa0
>
> As Peterz pointed out:
>
> | The thing is, many many smp_reschedule_interrupt() invocations don't
> | actually execute anything much at all and are only send to tickle the
> | return to user path (which does the actual preemption).
>
> This patch add write msr notrace to avoid the debug codes splash.
>
> Suggested-by: Peter Zijlstra <pet...@infradead.org>
> Suggested-by: Paolo Bonzini <pbonz...@redhat.com>
> Cc: Ingo Molnar <mi...@kernel.org>
> Cc: Mike Galbraith <efa...@gmx.de>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> Signed-off-by: Wanpeng Li <wanpeng...@hotmail.com>
> ---
> v1 -> v2:
> * add write msr notrace to avoid debug codes splash instead of slowdown a
> very frequent interrupt
>
> arch/x86/include/asm/apic.h | 4 ++--
> arch/x86/include/asm/msr.h | 15 +++++++++++++++
> arch/x86/kernel/kvm.c | 2 +-
> 3 files changed, 18 insertions(+), 3 deletions(-)
Could you please do this on top of -tip and also include the revert of:
# 1ec6ec14a294 x86/smp: Add irq_enter/exit() in
smp_reschedule_interrupt()
in your v3 patch, because I'd rather avoid rebasing x86/urgent.
Thanks,
Ingo
