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authorMichael S. Tsirkin <mst@redhat.com>2015-03-10 02:25:08 +0100
committerRusty Russell <rusty@rustcorp.com.au>2015-03-10 02:26:15 +0100
commit3d2a3774c1b046f548ebea0391a602fd5685a307 (patch)
treeb664aba0a08380007cb1ae1b53a743c65957c6bc
parentvirtio_blk: fix comment for virtio 1.0 (diff)
downloadlinux-3d2a3774c1b046f548ebea0391a602fd5685a307.tar.xz
linux-3d2a3774c1b046f548ebea0391a602fd5685a307.zip
virtio-balloon: do not call blocking ops when !TASK_RUNNING
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: stable@vger.kernel.org Reported-by: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Tested-by: Thomas Huth <thuth@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--drivers/virtio/virtio_balloon.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index b36fe56677d5..6a356e344f82 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -29,6 +29,7 @@
#include <linux/module.h>
#include <linux/balloon_compaction.h>
#include <linux/oom.h>
+#include <linux/wait.h>
/*
* Balloon device works in 4K page units. So each page is pointed to by
@@ -334,17 +335,25 @@ static int virtballoon_oom_notify(struct notifier_block *self,
static int balloon(void *_vballoon)
{
struct virtio_balloon *vb = _vballoon;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
set_freezable();
while (!kthread_should_stop()) {
s64 diff;
try_to_freeze();
- wait_event_interruptible(vb->config_change,
- (diff = towards_target(vb)) != 0
- || vb->need_stats_update
- || kthread_should_stop()
- || freezing(current));
+
+ add_wait_queue(&vb->config_change, &wait);
+ for (;;) {
+ if ((diff = towards_target(vb)) != 0 ||
+ vb->need_stats_update ||
+ kthread_should_stop() ||
+ freezing(current))
+ break;
+ wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+ }
+ remove_wait_queue(&vb->config_change, &wait);
+
if (vb->need_stats_update)
stats_handle_request(vb);
if (diff > 0)