| Message ID | 1516699646-7321-1-git-send-email-jasowang@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net,1/2] vhost: use mutex_lock_nested() in vhost_dev_lock_vqs() | expand |
On Tue, Jan 23, 2018 at 05:27:25PM +0800, Jason Wang wrote: > 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@syzkaller.appspotmail.com > Signed-off-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> > --- > drivers/vhost/vhost.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 33ac2b1..549771a 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -904,7 +904,7 @@ static void vhost_dev_lock_vqs(struct vhost_dev *d) > { > 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) > -- > 2.7.4
From: Jason Wang <jasowang@redhat.com> Date: Tue, 23 Jan 2018 17:27:25 +0800 > 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@syzkaller.appspotmail.com > Signed-off-by: Jason Wang <jasowang@redhat.com> Michael, I see you ACK'd this, meaning that you're OK with these two fixes going via my net tree? Thanks.
On Wed, Jan 24, 2018 at 04:38:30PM -0500, David Miller wrote: > From: Jason Wang <jasowang@redhat.com> > Date: Tue, 23 Jan 2018 17:27:25 +0800 > > > 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@syzkaller.appspotmail.com > > Signed-off-by: Jason Wang <jasowang@redhat.com> > > Michael, I see you ACK'd this, meaning that you're OK with these two > fixes going via my net tree? > > Thanks. Yes - this seems to be what Jason wanted (judging by the net tag in the subject) and I'm fine with it. Thanks a lot.
From: "Michael S. Tsirkin" <mst@redhat.com> Date: Wed, 24 Jan 2018 23:46:19 +0200 > On Wed, Jan 24, 2018 at 04:38:30PM -0500, David Miller wrote: >> From: Jason Wang <jasowang@redhat.com> >> Date: Tue, 23 Jan 2018 17:27:25 +0800 >> >> > 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@syzkaller.appspotmail.com >> > Signed-off-by: Jason Wang <jasowang@redhat.com> >> >> Michael, I see you ACK'd this, meaning that you're OK with these two >> fixes going via my net tree? >> >> Thanks. > > Yes - this seems to be what Jason wanted (judging by the net > tag in the subject) and I'm fine with it. > Thanks a lot. Great, not a problem, done.
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 33ac2b1..549771a 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -904,7 +904,7 @@ static void vhost_dev_lock_vqs(struct vhost_dev *d) { 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)
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@syzkaller.appspotmail.com Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/vhost/vhost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)