From: Benjamin Segall bsegall@google.com
commit 262de4102c7bb8e59f26a967a8ffe8cce85cc537 upstream.
single_task_running() is usually more general than need_resched() but CFS_BANDWIDTH throttling will use resched_task() when there is just one task to get the task to block. This was causing long-need_resched warnings and was likely allowing VMs to overrun their quota when halt polling.
Signed-off-by: Ben Segall bsegall@google.com Signed-off-by: Venkatesh Srinivas venkateshs@chromium.org Message-Id: 20210429162233.116849-1-venkateshs@chromium.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson jmattson@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- virt/kvm/kvm_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2838,7 +2838,8 @@ void kvm_vcpu_block(struct kvm_vcpu *vcp goto out; } poll_end = cur = ktime_get(); - } while (single_task_running() && ktime_before(cur, stop)); + } while (single_task_running() && !need_resched() && + ktime_before(cur, stop)); }
prepare_to_rcuwait(&vcpu->wait);