Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755994AbaDXLgU (ORCPT ); Thu, 24 Apr 2014 07:36:20 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:46447 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753670AbaDXIw7 (ORCPT ); Thu, 24 Apr 2014 04:52:59 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Rusty Russell , Luis Henriques Subject: [PATCH 3.11 045/182] virtio_balloon: don't softlockup on huge balloon changes. Date: Thu, 24 Apr 2014 09:49:30 +0100 Message-Id: <1398329507-5911-46-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1398329507-5911-1-git-send-email-luis.henriques@canonical.com> References: <1398329507-5911-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.9 -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: Luis Henriques --- drivers/virtio/virtio_balloon.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 1f572c0..cfda0a6 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -312,6 +312,12 @@ 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; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/