Linux v4.1-11355-g6aaf0da8728c

- Add patch to fix KVM sleeping in atomic issue (rhbz 1237143)
- Fix errant with_perf disable that removed perf entirely (rhbz 1237266)

1 files changed, 80 insertions, 0 deletions

diff --git a/sched-kvm-Fix-KVM-preempt_notifier-usage.patch b/sched-kvm-Fix-KVM-preempt_notifier-usage.patch
new file mode 100644
index 000000000..958b7fa98
--- /dev/null
+++ b/sched-kvm-Fix-KVM-preempt_notifier-usage.patch
@@ -0,0 +1,80 @@
+From: Peter Zijlstra <peterz@infradead.org>
+Date: Thu, 25 Jun 2015 14:55:14 +0200
+Subject: [PATCH] sched,kvm: Fix KVM preempt_notifier usage
+
+The preempt-notifier API needs to sleep with the addition of the
+static_key, we do however need to hold off preemption while modifying
+the preempt notifier list, otherwise a preemption could observe an
+inconsistent list state.
+
+There is no reason to have preemption disabled in the caller,
+registering a preempt notifier is a purely task local affair.
+
+Therefore move the preempt_disable into the functions and change the
+callers to a preemptible context.
+
+Cc: Gleb Natapov <gleb@kernel.org>
+Fixes: 1cde2930e154 ("sched/preempt: Add static_key() to preempt_notifiers")
+Reported-and-Tested-by: Pontus Fuchs <pontus.fuchs@gmail.com>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+---
+ kernel/sched/core.c | 11 +++++++++++
+ virt/kvm/kvm_main.c |  5 +++--
+ 2 files changed, 14 insertions(+), 2 deletions(-)
+
+diff --git a/kernel/sched/core.c b/kernel/sched/core.c
+index b803e1b8ab0c..6169c167ac98 100644
+--- a/kernel/sched/core.c
++++ b/kernel/sched/core.c
+@@ -2327,7 +2327,12 @@ static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;
+ void preempt_notifier_register(struct preempt_notifier *notifier)
+ {
+ 	static_key_slow_inc(&preempt_notifier_key);
++	/*
++	 * Avoid preemption while changing the preempt notifier list.
++	 */
++	preempt_disable();
+ 	hlist_add_head(&notifier->link, &current->preempt_notifiers);
++	preempt_enable();
+ }
+ EXPORT_SYMBOL_GPL(preempt_notifier_register);
+ 
+@@ -2339,7 +2344,13 @@ EXPORT_SYMBOL_GPL(preempt_notifier_register);
+  */
+ void preempt_notifier_unregister(struct preempt_notifier *notifier)
+ {
++	/*
++	 * Avoid preemption while changing the preempt notifier list.
++	 */
++	preempt_disable();
+ 	hlist_del(&notifier->link);
++	preempt_enable();
++
+ 	static_key_slow_dec(&preempt_notifier_key);
+ }
+ EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
+diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
+index 848af90b8091..7dc8d3eb9e1f 100644
+--- a/virt/kvm/kvm_main.c
++++ b/virt/kvm/kvm_main.c
+@@ -127,8 +127,9 @@ int vcpu_load(struct kvm_vcpu *vcpu)
+ 
+ 	if (mutex_lock_killable(&vcpu->mutex))
+ 		return -EINTR;
+-	cpu = get_cpu();
+ 	preempt_notifier_register(&vcpu->preempt_notifier);
++
++	cpu = get_cpu();
+ 	kvm_arch_vcpu_load(vcpu, cpu);
+ 	put_cpu();
+ 	return 0;
+@@ -138,8 +139,8 @@ void vcpu_put(struct kvm_vcpu *vcpu)
+ {
+ 	preempt_disable();
+ 	kvm_arch_vcpu_put(vcpu);
+-	preempt_notifier_unregister(&vcpu->preempt_notifier);
+ 	preempt_enable();
++	preempt_notifier_unregister(&vcpu->preempt_notifier);
+ 	mutex_unlock(&vcpu->mutex);
+ }
+