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| author | Rusty Russell <rusty@rustcorp.com.au> | 2014-03-13 11:23:38 +1030 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-05-13 13:32:48 +0200 |
| commit | f52e31dc5f5f61db5bd08576b8189ada2a8c9b82 (patch) | |
| tree | a8de9c3b426af2e86f57b22b0d0fad5ca7ac25ee | |
| parent | 771004298d9a73ff1bca0b4ff5168c74d3ff7af0 (diff) | |
| download | lwn-f52e31dc5f5f61db5bd08576b8189ada2a8c9b82.tar.gz lwn-f52e31dc5f5f61db5bd08576b8189ada2a8c9b82.zip | |
virtio_balloon: don't softlockup on huge balloon changes.
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>
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 34bdabaecbd6..36e7859a31aa 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -310,6 +310,12 @@ 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; } |