| From 1f74ef0f2d7d692fcd615621e0e734c3e7771413 Mon Sep 17 00:00:00 2001 |
| From: Rusty Russell <rusty@rustcorp.com.au> |
| Date: Thu, 13 Mar 2014 11:23:38 +1030 |
| Subject: virtio_balloon: don't softlockup on huge balloon changes. |
| |
| From: Rusty Russell <rusty@rustcorp.com.au> |
| |
| 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 <gopchaud@in.ibm.com> |
| Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| 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; |
| } |
