On Thu, 2018-12-06 at 20:58 +0000, Parav Pandit wrote:
> > -----Original Message-----
> > From: Doug Ledford <dledford@xxxxxxxxxx>
> > Sent: Thursday, December 6, 2018 2:55 PM
> > To: Parav Pandit <parav@xxxxxxxxxxxx>; Leon Romanovsky
> > <leon@xxxxxxxxxx>
> > Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>; Mark Zhang
> > <markz@xxxxxxxxxxxx>; RDMA mailing list <linux-rdma@xxxxxxxxxxxxxxx>
> > Subject: Re: [PATCH rdma-rc] IB/core: Don't match bond master filter for
> > closed slaves
> >
> > On Thu, 2018-12-06 at 19:10 +0000, Parav Pandit wrote:
> > > > -----Original Message-----
> > > > From: Leon Romanovsky <leon@xxxxxxxxxx>
> > > > Sent: Thursday, December 6, 2018 12:48 PM
> > > > To: Doug Ledford <dledford@xxxxxxxxxx>
> > > > Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>; Mark Zhang
> > > > <markz@xxxxxxxxxxxx>; RDMA mailing list
> > > > <linux-rdma@xxxxxxxxxxxxxxx>; Parav Pandit <parav@xxxxxxxxxxxx>
> > > > Subject: Re: [PATCH rdma-rc] IB/core: Don't match bond master filter
> > > > for closed slaves
> > > >
> > > > On Thu, Dec 06, 2018 at 12:19:30PM -0500, Doug Ledford wrote:
> > > > > On Wed, 2018-12-05 at 15:50 +0200, Leon Romanovsky wrote:
> > > > > > From: Mark Zhang <markz@xxxxxxxxxxxx>
> > > > > >
> > > > > > The "modprobe -r mlx4_en" will close bond slaves and in such
> > > > > > case the rdma_dev would be NULL, so no match should be returned.
> > > > >
> > > > > I'm not groking your commit message. What happens without this
> > patch?
> > > > We will see calltrace due to the fact that NULL is passed down the
> > > > stack through rdma_is_upper_dev_rcu() upto
> > netdev_walk_all_upper_dev_rcu().
> > > I see this patch being sent for -rc which I was not sure when I reviewed.
> > > Commit message needs to change as below.
> > >
> > > When mlx4_en driver is unloaded, and configured to use bond devices,
> > get_netdev() callback returns NULL because associated netdev is
> > unregistered.
> > > Therefore, similar to other filter() routines, fix
> > is_upper_ndev_bond_master_filter() to handle NULL netdev.
> > > Without this check, a call trace is observed.
> >
> > Does it catch a WARN_ON later on, or does it oops?
> >
> It is NULL reference oops.
Yep, I just got through following the trail. It oopses in
netdev_next_upper_dev_rcu().
Ok, patch applied to for-rc with commit message fixups.
--
Doug Ledford <dledford@xxxxxxxxxx>
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