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authorSasha Levin <sasha.levin@oracle.com>2012-10-19 12:11:55 -0400
committerAvi Kivity <avi@redhat.com>2012-10-22 18:03:28 +0200
commitc5e015d4949aa665c486cae6884beb00b97e3dea (patch)
tree73dc461f6cfbf4aeed81071ee96aad3f109f56ec
parent7f46ddbd487e0d0528d89534fdfb31d885977804 (diff)
downloadop-kernel-dev-c5e015d4949aa665c486cae6884beb00b97e3dea.zip
op-kernel-dev-c5e015d4949aa665c486cae6884beb00b97e3dea.tar.gz
KVM guest: exit idleness when handling KVM_PV_REASON_PAGE_NOT_PRESENT
KVM_PV_REASON_PAGE_NOT_PRESENT kicks cpu out of idleness, but we haven't marked that spot as an exit from idleness. Not doing so can cause RCU warnings such as: [ 732.788386] =============================== [ 732.789803] [ INFO: suspicious RCU usage. ] [ 732.790032] 3.7.0-rc1-next-20121019-sasha-00002-g6d8d02d-dirty #63 Tainted: G W [ 732.790032] ------------------------------- [ 732.790032] include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle! [ 732.790032] [ 732.790032] other info that might help us debug this: [ 732.790032] [ 732.790032] [ 732.790032] RCU used illegally from idle CPU! [ 732.790032] rcu_scheduler_active = 1, debug_locks = 1 [ 732.790032] RCU used illegally from extended quiescent state! [ 732.790032] 2 locks held by trinity-child31/8252: [ 732.790032] #0: (&rq->lock){-.-.-.}, at: [<ffffffff83a67528>] __schedule+0x178/0x8f0 [ 732.790032] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff81152bde>] cpuacct_charge+0xe/0x200 [ 732.790032] [ 732.790032] stack backtrace: [ 732.790032] Pid: 8252, comm: trinity-child31 Tainted: G W 3.7.0-rc1-next-20121019-sasha-00002-g6d8d02d-dirty #63 [ 732.790032] Call Trace: [ 732.790032] [<ffffffff8118266b>] lockdep_rcu_suspicious+0x10b/0x120 [ 732.790032] [<ffffffff81152c60>] cpuacct_charge+0x90/0x200 [ 732.790032] [<ffffffff81152bde>] ? cpuacct_charge+0xe/0x200 [ 732.790032] [<ffffffff81158093>] update_curr+0x1a3/0x270 [ 732.790032] [<ffffffff81158a6a>] dequeue_entity+0x2a/0x210 [ 732.790032] [<ffffffff81158ea5>] dequeue_task_fair+0x45/0x130 [ 732.790032] [<ffffffff8114ae29>] dequeue_task+0x89/0xa0 [ 732.790032] [<ffffffff8114bb9e>] deactivate_task+0x1e/0x20 [ 732.790032] [<ffffffff83a67c29>] __schedule+0x879/0x8f0 [ 732.790032] [<ffffffff8117e20d>] ? trace_hardirqs_off+0xd/0x10 [ 732.790032] [<ffffffff810a37a5>] ? kvm_async_pf_task_wait+0x1d5/0x2b0 [ 732.790032] [<ffffffff83a67cf5>] schedule+0x55/0x60 [ 732.790032] [<ffffffff810a37c4>] kvm_async_pf_task_wait+0x1f4/0x2b0 [ 732.790032] [<ffffffff81139e50>] ? abort_exclusive_wait+0xb0/0xb0 [ 732.790032] [<ffffffff81139c25>] ? prepare_to_wait+0x25/0x90 [ 732.790032] [<ffffffff810a3a66>] do_async_page_fault+0x56/0xa0 [ 732.790032] [<ffffffff83a6a6e8>] async_page_fault+0x28/0x30 Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Acked-by: Gleb Natapov <gleb@redhat.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
-rw-r--r--arch/x86/kernel/kvm.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index b3e5e51..4180a87 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -247,7 +247,10 @@ 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();
break;
case KVM_PV_REASON_PAGE_READY:
rcu_irq_enter();
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