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Wed, 26 Mar 2025 10:49:54 -0700 (PDT) Date: Wed, 26 Mar 2025 10:49:53 -0700 From: Stanislav Fomichev To: Cosmin Ratiu Cc: "pabeni@redhat.com" , "edumazet@google.com" , "netdev@vger.kernel.org" , "davem@davemloft.net" , "sdf@fomichev.me" , "kuba@kernel.org" Subject: Re: [PATCH net-next 2/9] net: hold instance lock during NETDEV_REGISTER/UP/UNREGISTER Message-ID: References: <20250325213056.332902-1-sdf@fomichev.me> <20250325213056.332902-3-sdf@fomichev.me> <86b753c439badc25968a01d03ed59b734886ad9b.camel@nvidia.com> <672305efd02d3d29520f49a1c18e2f4da6e90902.camel@nvidia.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <672305efd02d3d29520f49a1c18e2f4da6e90902.camel@nvidia.com> On 03/26, Cosmin Ratiu wrote: > On Wed, 2025-03-26 at 08:23 -0700, Stanislav Fomichev wrote: > > @@ -2028,7 +2028,7 @@ int unregister_netdevice_notifier(struct > > notifier_block *nb) > >   > >   for_each_net(net) { > >   __rtnl_net_lock(net); > > - call_netdevice_unregister_net_notifiers(nb, net, > > true); > > + call_netdevice_unregister_net_notifiers(nb, net, > > NULL); > >   __rtnl_net_unlock(net); > >   } > > I tested. The deadlock is back now, because dev != NULL and if the lock > is held (like in the below stack), the mutex_lock will be attempted > again: I think I'm missing something. In this case I'm not sure why the original "fix" worked. You, presumably, use mlx5? And you just move this single device into a new netns? Or there is a couple of other mlx5 devices still hanging in the root netns? I'll try to take a look more at register_netdevice_notifier_net under mlx5..