On Wed, 25 Feb 2015 16:11:27 +0100 Cornelia Huck <cornelia.h...@de.ibm.com> wrote:
> 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> Right, I just applied the patch on my system, too, and the problem is indeed gone! Thanks for the quick fix! Tested-by: Thomas Huth <th...@linux.vnet.ibm.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
