On Tue, May 23, 2023 at 6:05 PM Jakub Kicinski <k...@kernel.org> wrote: > > On Tue, 23 May 2023 17:46:20 +0200 Jason A. Donenfeld wrote: > > > Freed by task 41: > > > __kmem_cache_free+0x264/0x3c0 mm/slub.c:3799 > > > device_release+0x95/0x1c0 > > > kobject_cleanup lib/kobject.c:683 [inline] > > > kobject_release lib/kobject.c:714 [inline] > > > kref_put include/linux/kref.h:65 [inline] > > > kobject_put+0x228/0x470 lib/kobject.c:731 > > > netdev_run_todo+0xe5a/0xf50 net/core/dev.c:10400 > > > > So that means the memory in question is actually the one that's > > allocated and freed by the networking stack. Specifically, dev.c:10626 > > is allocating a struct net_device with a trailing struct wg_device (its > > priv_data). However, wg_device does not have any struct timer_lists in > > it, and I don't see how net_device's watchdog_timer would be related to > > the stacktrace which is clearly operating over a wg_peer timer. > > > > So what on earth is going on here? > > Your timer had the pleasure of getting queued _after_ a dead watchdog > timer, no? IOW it tries to update the ->next pointer of a queued > watchdog timer. We should probably do: > > diff --git a/net/core/dev.c b/net/core/dev.c > index 374d38fb8b9d..f3ed20ebcf5a 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -10389,6 +10389,8 @@ void netdev_run_todo(void) > WARN_ON(rcu_access_pointer(dev->ip_ptr)); > WARN_ON(rcu_access_pointer(dev->ip6_ptr)); > > + WARN_ON(timer_shutdown_sync(&dev->watchdog_timer)); > + > if (dev->priv_destructor) > dev->priv_destructor(dev); > if (dev->needs_free_netdev) > > to catch how that watchdog_timer is getting queued. Would that make > sense, Eric?
Would this case be catched at the time the device is freed ? (CONFIG_DEBUG_OBJECTS_FREE=y or something)