2016-10-18 17:24 GMT+08:00 Ingo Molnar <[email protected]>: > > * Wanpeng Li <[email protected]> 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 <[email protected]> >> Suggested-by: Paolo Bonzini <[email protected]> >> Cc: Ingo Molnar <[email protected]> >> Cc: Mike Galbraith <[email protected]> >> Cc: Peter Zijlstra <[email protected]> >> Cc: Thomas Gleixner <[email protected]> >> Cc: Paolo Bonzini <[email protected]> >> Signed-off-by: Wanpeng Li <[email protected]> >> --- >> 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.
It seems that v2 still doesn't handle paravirt part correctly, I will revert 1ec6ec14a294 in v3 when I figure it out. Regards, Wanpeng Li
