From 64f638c7c44fa87e65f51eaf0f8302b9cba2d696 Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Mon, 1 Nov 2010 17:03:44 +0800 Subject: [PATCH] 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 Acked-by: Gleb Natapov Signed-off-by: Marcelo Tosatti --- virt/kvm/async_pf.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c index 100c66ee0220..74268b4c2ee1 100644 --- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -196,7 +196,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) { 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 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) 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; }