Messages in this thread | | | Date | Tue, 27 Nov 2012 19:47:37 +0200 | From | Gleb Natapov <> | Subject | Re: [RFC PATCH] Fix abnormal rcu dynticks_nesting values related to async page fault |
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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.
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