[lkml]   [2016]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Subject[PATCH v8 0/2] x86/apic: x2apic write eoi msr notrace
 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.


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(-)


 \ /
  Last update: 2016-11-07 04:27    [W:0.043 / U:0.116 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site