KVM: fix the race while wakeup all pv guest
In kvm_async_pf_wakeup_all(), we add a dummy apf to vcpu->async_pf.done
without holding vcpu->async_pf.lock, it will break if we are handling apfs
at this time.
Also use 'list_empty_careful()' instead of 'list_empty()'
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index 100c66e..74268b4 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -196,7 +196,7 @@
{
struct kvm_async_pf *work;
- if (!list_empty(&vcpu->async_pf.done))
+ if (!list_empty_careful(&vcpu->async_pf.done))
return 0;
work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
@@ -207,7 +207,10 @@
get_page(bad_page);
INIT_LIST_HEAD(&work->queue); /* for list_del to work */
+ spin_lock(&vcpu->async_pf.lock);
list_add_tail(&work->link, &vcpu->async_pf.done);
+ spin_unlock(&vcpu->async_pf.lock);
+
vcpu->async_pf.queued++;
return 0;
}