On Wed, 25 Feb 2015 15:36:02 +0100 "Michael S. Tsirkin" <m...@redhat.com> wrote:
> virtio balloon has this code: > wait_event_interruptible(vb->config_change, > (diff = towards_target(vb)) != 0 > || vb->need_stats_update > || kthread_should_stop() > || freezing(current)); > > Which is a problem because towards_target() call might block after > wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing > the task_struct::state collision typical of nesting of sleeping > primitives > > See also http://lwn.net/Articles/628628/ or Thomas's > bug report > http://article.gmane.org/gmane.linux.kernel.virtualization/24846 > for a fuller explanation. > > To fix, rewrite using wait_woken. > > Cc: sta...@vger.kernel.org > Reported-by: Thomas Huth <th...@linux.vnet.ibm.com> > Signed-off-by: Michael S. Tsirkin <m...@redhat.com> > --- > > changes from v1: > remove wait_event_interruptible > noticed by Cornelia Huck <cornelia.h...@de.ibm.com> > > drivers/virtio/virtio_balloon.c | 19 ++++++++++++++----- > 1 file changed, 14 insertions(+), 5 deletions(-) > I was able to reproduce Thomas' original problem and can confirm that it is gone with this patch. Reviewed-by: Cornelia Huck <cornelia.h...@de.ibm.com> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
