This is a note to let you know that I've just added the patch titled
vhost: use mutex_lock_nested() in vhost_dev_lock_vqs()
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
vhost-use-mutex_lock_nested-in-vhost_dev_lock_vqs.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e9cb4239134c860e5f92c75bf5321bd377bb505b Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@xxxxxxxxxx>
Date: Tue, 23 Jan 2018 17:27:25 +0800
Subject: vhost: use mutex_lock_nested() in vhost_dev_lock_vqs()
From: Jason Wang <jasowang@xxxxxxxxxx>
commit e9cb4239134c860e5f92c75bf5321bd377bb505b upstream.
We used to call mutex_lock() in vhost_dev_lock_vqs() which tries to
hold mutexes of all virtqueues. This may confuse lockdep to report a
possible deadlock because of trying to hold locks belong to same
class. Switch to use mutex_lock_nested() to avoid false positive.
Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
Reported-by: syzbot+dbb7c1161485e61b0241@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/vhost/vhost.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -849,7 +849,7 @@ static void vhost_dev_lock_vqs(struct vh
{
int i = 0;
for (i = 0; i < d->nvqs; ++i)
- mutex_lock(&d->vqs[i]->mutex);
+ mutex_lock_nested(&d->vqs[i]->mutex, i);
}
static void vhost_dev_unlock_vqs(struct vhost_dev *d)
Patches currently in stable-queue which might be from jasowang@xxxxxxxxxx are
queue-4.9/vhost-use-mutex_lock_nested-in-vhost_dev_lock_vqs.patch
queue-4.9/ptr_ring-fail-early-if-queue-occupies-more-than-kmalloc_max_size.patch