lkml.org 
[lkml]   [2012]   [Nov]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] Fix abnormal rcu dynticks_nesting values related to async page fault
On Tue, Nov 27, 2012 at 06:30:32PM +0100, Frederic Weisbecker wrote:
> 2012/11/27 Gleb Natapov <gleb@redhat.com>:
> > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> > index 4180a87..636800d 100644
> > --- a/arch/x86/kernel/kvm.c
> > +++ b/arch/x86/kernel/kvm.c
> > @@ -113,7 +113,7 @@ void kvm_async_pf_task_wait(u32 token)
> > int cpu, idle;
> >
> > cpu = get_cpu();
> > - idle = idle_cpu(cpu);
> > + idle = is_idle_task(current);
>
> I suggest this part goes to a standalone patch.
>
> > put_cpu();
> >
> > spin_lock(&b->lock);
> > @@ -247,10 +247,7 @@ do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
> > break;
> > case KVM_PV_REASON_PAGE_NOT_PRESENT:
> > /* page is swapped out by the host. */
> > - rcu_irq_enter();
> > - exit_idle();
> > kvm_async_pf_task_wait((u32)read_cr2());
> > - rcu_irq_exit();
>
> Hmm, we still need those above around. I believe we just need to add
> rcu_user_exit() in the beginning of that case.
The exception may happen in kernel space too. Is calling rcu_user_exit()
still OK? Also why calling exit_idle() if we are not exiting idle?

--
Gleb.


\
 
 \ /
  Last update: 2012-11-27 19:21    [W:1.781 / U:0.368 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site