From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933105AbaEKTW4 (ORCPT ); Sun, 11 May 2014 15:22:56 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48152 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933084AbaEKTWw (ORCPT ); Sun, 11 May 2014 15:22:52 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gopesh Kumar Chaudhary , Rusty Russell Subject: [PATCH 3.10 11/48] virtio_balloon: dont softlockup on huge balloon changes. Date: Sun, 11 May 2014 21:19:45 +0200 Message-Id: <20140511191949.667850383@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140511191948.079900414@linuxfoundation.org> References: <20140511191948.079900414@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rusty Russell commit 1f74ef0f2d7d692fcd615621e0e734c3e7771413 upstream. When adding or removing 100G from a balloon: BUG: soft lockup - CPU#0 stuck for 22s! [vballoon:367] We have a wait_event_interruptible(), but the condition is always true (more ballooning to do) so we don't ever sleep. We also have a wait_event() for the host to ack, but that is also always true as QEMU is synchronous for balloon operations. Reported-by: Gopesh Kumar Chaudhary Signed-off-by: Rusty Russell Signed-off-by: Greg Kroah-Hartman --- drivers/virtio/virtio_balloon.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -311,6 +311,12 @@ static int balloon(void *_vballoon) else if (diff < 0) leak_balloon(vb, -diff); update_balloon_size(vb); + + /* + * For large balloon changes, we could spend a lot of time + * and always have work to do. Be nice if preempt disabled. + */ + cond_resched(); } return 0; }