On Tue, Apr 03, 2012 at 01:52:26PM +0300, Gleb Natapov wrote: > On Mon, Apr 02, 2012 at 08:54:32PM -0400, Sasha Levin wrote: > > Hi all, > > > > I got the spew at the bottom of the mail in a KVM guest using the KVM tools and running trinity. > > > > I'm not quite sure how default_idle managed to trigger a pagefault, so that part looks odd to me. > > > This is not regular page fault. This is async page fault that tells the > guest that a page, previously swapped out by hypervisor, is now swapped > back in and it can happen while vcpu is idle. The code does not leave > idle state properly though. We probably need to call rcu_irq_enter() > there. Will look into it. > The patch below solves it for me: "Page ready" async PF can kick vcpu out of idle state much like IRQ. We need to tell RCU about this. Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index f0c6fd6..380079f 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -38,6 +38,7 @@ #include <asm/traps.h> #include <asm/desc.h> #include <asm/tlbflush.h> +#include <asm/idle.h> static int kvmapf = 1; @@ -253,7 +254,10 @@ do_async_page_fault(struct pt_regs *regs, unsigned long error_code) kvm_async_pf_task_wait((u32)read_cr2()); break; case KVM_PV_REASON_PAGE_READY: + rcu_irq_enter(); + exit_idle(); kvm_async_pf_task_wake((u32)read_cr2()); + rcu_irq_exit(); break; } } -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
