linux.git/net/core/link_watch.c, branch v6.9 Linux kernel source tree net: add netdev_set_operstate() helper 2024-02-14T11:20:13+00:00 Eric Dumazet edumazet@google.com 2024-02-13T06:32:42+00:00 6a2968ee1ee2cc6fce30f6f5724442b34b1483b3 dev_base_lock is going away, add netdev_set_operstate() helper so that hsr does not have to know core internals. Remove dev_base_lock acquisition from rfc2863_policy() v3: use an "unsigned int" for dev->operstate, so that try_cmpxchg() can work on all arches. ( https://lore.kernel.org/oe-kbuild-all/202402081918.OLyGaea3-lkp@intel.com/ ) Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
dev_base_lock is going away, add netdev_set_operstate() helper
so that hsr does not have to know core internals.

Remove dev_base_lock acquisition from rfc2863_policy()

v3: use an "unsigned int" for dev->operstate,
    so that try_cmpxchg() can work on all arches.
        ( https://lore.kernel.org/oe-kbuild-all/202402081918.OLyGaea3-lkp@intel.com/ )

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net-sysfs: convert dev->operstate reads to lockless ones 2024-02-14T11:20:13+00:00 Eric Dumazet edumazet@google.com 2024-02-13T06:32:39+00:00 004d138364fd10dd5ff8ceb54cfdc2d792a7b338 operstate_show() can omit dev_base_lock acquisition only to read dev->operstate. Annotate accesses to dev->operstate. Writers still acquire dev_base_lock for mutual exclusion. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
operstate_show() can omit dev_base_lock acquisition only
to read dev->operstate.

Annotate accesses to dev->operstate.

Writers still acquire dev_base_lock for mutual exclusion.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Revert "net: rtnetlink: remove local list in __linkwatch_run_queue()" 2023-12-11T10:57:16+00:00 Johannes Berg johannes.berg@intel.com 2023-12-08T09:52:15+00:00 9a64d4c93eee6b2efb7a02ec98d9480946424509 This reverts commit b8dbbbc535a9 ("net: rtnetlink: remove local list in __linkwatch_run_queue()"). It's evidently broken when there's a non-urgent work that gets added back, and then the loop can never finish. While reverting, add a note about that. Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Fixes: b8dbbbc535a9 ("net: rtnetlink: remove local list in __linkwatch_run_queue()") Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
This reverts commit b8dbbbc535a9 ("net: rtnetlink: remove local list
in __linkwatch_run_queue()"). It's evidently broken when there's a
non-urgent work that gets added back, and then the loop can never
finish.

While reverting, add a note about that.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: b8dbbbc535a9 ("net: rtnetlink: remove local list in __linkwatch_run_queue()")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: rtnetlink: remove local list in __linkwatch_run_queue() 2023-12-07T03:25:43+00:00 Johannes Berg johannes.berg@intel.com 2023-12-05T16:00:11+00:00 b8dbbbc535a95acd66035cf75872cd7524c0b12f Due to linkwatch_forget_dev() (and perhaps others?) checking for list_empty(&dev->link_watch_list), we must have all manipulations of even the local on-stack list 'wrk' here under spinlock, since even that list can be reached otherwise via dev->link_watch_list. This is already the case, but makes this a bit counter-intuitive, often local lists are used to _not_ have to use locking for their local use. Remove the local list as it doesn't seem to serve any purpose. While at it, move a variable declaration into the loop using it. Reviewed-by: Jiri Pirko <jiri@nvidia.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Link: https://lore.kernel.org/r/20231205170011.56576dcc1727.I698b72219d9f6ce789bd209b8f6dffd0ca32a8f2@changeid Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Due to linkwatch_forget_dev() (and perhaps others?) checking for
list_empty(&dev->link_watch_list), we must have all manipulations
of even the local on-stack list 'wrk' here under spinlock, since
even that list can be reached otherwise via dev->link_watch_list.

This is already the case, but makes this a bit counter-intuitive,
often local lists are used to _not_ have to use locking for their
local use.

Remove the local list as it doesn't seem to serve any purpose.
While at it, move a variable declaration into the loop using it.

Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20231205170011.56576dcc1727.I698b72219d9f6ce789bd209b8f6dffd0ca32a8f2@changeid
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: core: synchronize link-watch when carrier is queried 2023-12-06T04:16:45+00:00 Johannes Berg johannes.berg@intel.com 2023-12-04T20:47:07+00:00 facd15dfd69122042502d99ab8c9f888b48ee994 There are multiple ways to query for the carrier state: through rtnetlink, sysfs, and (possibly) ethtool. Synchronize linkwatch work before these operations so that we don't have a situation where userspace queries the carrier state between the driver's carrier off->on transition and linkwatch running and expects it to work, when really (at least) TX cannot work until linkwatch has run. I previously posted a longer explanation of how this applies to wireless [1] but with this wireless can simply query the state before sending data, to ensure the kernel is ready for it. [1] https://lore.kernel.org/all/346b21d87c69f817ea3c37caceb34f1f56255884.camel@sipsolutions.net/ Signed-off-by: Johannes Berg <johannes.berg@intel.com> Reviewed-by: Jiri Pirko <jiri@nvidia.com> Link: https://lore.kernel.org/r/20231204214706.303c62768415.I1caedccae72ee5a45c9085c5eb49c145ce1c0dd5@changeid Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
There are multiple ways to query for the carrier state: through
rtnetlink, sysfs, and (possibly) ethtool. Synchronize linkwatch
work before these operations so that we don't have a situation
where userspace queries the carrier state between the driver's
carrier off->on transition and linkwatch running and expects it
to work, when really (at least) TX cannot work until linkwatch
has run.

I previously posted a longer explanation of how this applies to
wireless [1] but with this wireless can simply query the state
before sending data, to ensure the kernel is ready for it.

[1] https://lore.kernel.org/all/346b21d87c69f817ea3c37caceb34f1f56255884.camel@sipsolutions.net/

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231204214706.303c62768415.I1caedccae72ee5a45c9085c5eb49c145ce1c0dd5@changeid
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: linkwatch: only report IF_OPER_LOWERLAYERDOWN if iflink is actually down 2022-11-16T09:45:00+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2022-11-14T14:42:56+00:00 8c55facecd7ade835287298ce325f930d888d8ec RFC 2863 says: The lowerLayerDown state is also a refinement on the down state. This new state indicates that this interface runs "on top of" one or more other interfaces (see ifStackTable) and that this interface is down specifically because one or more of these lower-layer interfaces are down. DSA interfaces are virtual network devices, stacked on top of the DSA master, but they have a physical MAC, with a PHY that reports a real link status. But since DSA (perhaps improperly) uses an iflink to describe the relationship to its master since commit c084080151e1 ("dsa: set ->iflink on slave interfaces to the ifindex of the parent"), default_operstate() will misinterpret this to mean that every time the carrier of a DSA interface is not ok, it is because of the master being not ok. In fact, since commit c0a8a9c27493 ("net: dsa: automatically bring user ports down when master goes down"), DSA cannot even in theory be in the lowerLayerDown state, because it just calls dev_close_many(), thereby going down, when the master goes down. We could revert the commit that creates an iflink between a DSA user port and its master, especially since now we have an alternative IFLA_DSA_MASTER which has less side effects. But there may be tooling in use which relies on the iflink, which has existed since 2009. We could also probably do something local within DSA to overwrite what rfc2863_policy() did, in a way similar to hsr_set_operstate(), but this seems like a hack. What seems appropriate is to follow the iflink, and check the carrier status of that interface as well. If that's down too, yes, keep reporting lowerLayerDown, otherwise just down. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
RFC 2863 says:

   The lowerLayerDown state is also a refinement on the down state.
   This new state indicates that this interface runs "on top of" one or
   more other interfaces (see ifStackTable) and that this interface is
   down specifically because one or more of these lower-layer interfaces
   are down.

DSA interfaces are virtual network devices, stacked on top of the DSA
master, but they have a physical MAC, with a PHY that reports a real
link status.

But since DSA (perhaps improperly) uses an iflink to describe the
relationship to its master since commit c084080151e1 ("dsa: set ->iflink
on slave interfaces to the ifindex of the parent"), default_operstate()
will misinterpret this to mean that every time the carrier of a DSA
interface is not ok, it is because of the master being not ok.

In fact, since commit c0a8a9c27493 ("net: dsa: automatically bring user
ports down when master goes down"), DSA cannot even in theory be in the
lowerLayerDown state, because it just calls dev_close_many(), thereby
going down, when the master goes down.

We could revert the commit that creates an iflink between a DSA user
port and its master, especially since now we have an alternative
IFLA_DSA_MASTER which has less side effects. But there may be tooling in
use which relies on the iflink, which has existed since 2009.

We could also probably do something local within DSA to overwrite what
rfc2863_policy() did, in a way similar to hsr_set_operstate(), but this
seems like a hack.

What seems appropriate is to follow the iflink, and check the carrier
status of that interface as well. If that's down too, yes, keep
reporting lowerLayerDown, otherwise just down.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: rename reference+tracking helpers 2022-06-10T04:52:55+00:00 Jakub Kicinski kuba@kernel.org 2022-06-08T04:39:55+00:00 d62607c3fe45911b2331fac073355a8c914bbde2 Netdev reference helpers have a dev_ prefix for historic reasons. Renaming the old helpers would be too much churn but we can rename the tracking ones which are relatively recent and should be the default for new code. Rename: dev_hold_track() -> netdev_hold() dev_put_track() -> netdev_put() dev_replace_track() -> netdev_ref_replace() Link: https://lore.kernel.org/r/20220608043955.919359-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Netdev reference helpers have a dev_ prefix for historic
reasons. Renaming the old helpers would be too much churn
but we can rename the tracking ones which are relatively
recent and should be the default for new code.

Rename:
 dev_hold_track()    -> netdev_hold()
 dev_put_track()     -> netdev_put()
 dev_replace_track() -> netdev_ref_replace()

Link: https://lore.kernel.org/r/20220608043955.919359-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: extract a few internals from netdevice.h 2022-04-08T03:32:09+00:00 Jakub Kicinski kuba@kernel.org 2022-04-06T21:37:54+00:00 6264f58ca0e54e41d63c2d00334a48bac28fbf30 There's a number of functions and static variables used under net/core/ but not from the outside. We currently dump most of them into netdevice.h. That bad for many reasons: - netdevice.h is very cluttered, hard to figure out what the APIs are; - netdevice.h is very long; - we have to touch netdevice.h more which causes expensive incremental builds. Create a header under net/core/ and move some declarations. The new header is also a bit of a catch-all but that's fine, if we create more specific headers people will likely over-think where their declaration fit best. And end up putting them in netdevice.h, again. More work should be done on splitting netdevice.h into more targeted headers, but that'd be more time consuming so small steps. Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
There's a number of functions and static variables used
under net/core/ but not from the outside. We currently
dump most of them into netdevice.h. That bad for many
reasons:
 - netdevice.h is very cluttered, hard to figure out
   what the APIs are;
 - netdevice.h is very long;
 - we have to touch netdevice.h more which causes expensive
   incremental builds.

Create a header under net/core/ and move some declarations.

The new header is also a bit of a catch-all but that's
fine, if we create more specific headers people will
likely over-think where their declaration fit best.
And end up putting them in netdevice.h, again.

More work should be done on splitting netdevice.h into more
targeted headers, but that'd be more time consuming so small
steps.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: refine dev_put()/dev_hold() debugging 2022-02-05T15:22:45+00:00 Eric Dumazet edumazet@google.com 2022-02-04T22:42:37+00:00 4c6c11ea0f7b00a1894803efe980dfaf3b074886 We are still chasing some syzbot reports where we think a rogue dev_put() is called with no corresponding prior dev_hold(). Unfortunately it eats a reference on dev->dev_refcnt taken by innocent dev_hold_track(), meaning that the refcount saturation splat comes too late to be useful. Make sure that 'not tracked' dev_put() and dev_hold() better use CONFIG_NET_DEV_REFCNT_TRACKER=y debug infrastructure: Prior patch in the series allowed ref_tracker_alloc() and ref_tracker_free() to be called with a NULL @trackerp parameter, and to use a separate refcount only to detect too many put() even in the following case: dev_hold_track(dev, tracker_1, GFP_ATOMIC); dev_hold(dev); dev_put(dev); dev_put(dev); // Should complain loudly here. dev_put_track(dev, tracker_1); // instead of here Add clarification about netdev_tracker_alloc() role. v2: I replaced the dev_put() in linkwatch_do_dev() with __dev_put() because callers called netdev_tracker_free(). Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
We are still chasing some syzbot reports where we think a rogue dev_put()
is called with no corresponding prior dev_hold().
Unfortunately it eats a reference on dev->dev_refcnt taken by innocent
dev_hold_track(), meaning that the refcount saturation splat comes
too late to be useful.

Make sure that 'not tracked' dev_put() and dev_hold() better use
CONFIG_NET_DEV_REFCNT_TRACKER=y debug infrastructure:

Prior patch in the series allowed ref_tracker_alloc() and ref_tracker_free()
to be called with a NULL @trackerp parameter, and to use a separate refcount
only to detect too many put() even in the following case:

dev_hold_track(dev, tracker_1, GFP_ATOMIC);
 dev_hold(dev);
 dev_put(dev);
 dev_put(dev); // Should complain loudly here.
dev_put_track(dev, tracker_1); // instead of here

Add clarification about netdev_tracker_alloc() role.

v2: I replaced the dev_put() in linkwatch_do_dev()
    with __dev_put() because callers called netdev_tracker_free().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: linkwatch: be more careful about dev->linkwatch_dev_tracker 2021-12-15T02:45:58+00:00 Eric Dumazet edumazet@google.com 2021-12-14T05:19:55+00:00 123e495ecc25d32cf3e7958f794013236abdf0d4 Apparently a concurrent linkwatch_add_event() could run while we are in __linkwatch_run_queue(). We need to free dev->linkwatch_dev_tracker tracker under lweventlist_lock protection to avoid this race. syzbot report: [ 77.935949][ T3661] reference already released. [ 77.941015][ T3661] allocated in: [ 77.944482][ T3661] linkwatch_fire_event+0x202/0x260 [ 77.950318][ T3661] netif_carrier_on+0x9c/0x100 [ 77.955120][ T3661] __ieee80211_sta_join_ibss+0xc52/0x1590 [ 77.960888][ T3661] ieee80211_sta_create_ibss.cold+0xd2/0x11f [ 77.966908][ T3661] ieee80211_ibss_work.cold+0x30e/0x60f [ 77.972483][ T3661] ieee80211_iface_work+0xb70/0xd00 [ 77.977715][ T3661] process_one_work+0x9ac/0x1680 [ 77.982671][ T3661] worker_thread+0x652/0x11c0 [ 77.987371][ T3661] kthread+0x405/0x4f0 [ 77.991465][ T3661] ret_from_fork+0x1f/0x30 [ 77.995895][ T3661] freed in: [ 77.999006][ T3661] linkwatch_do_dev+0x96/0x160 [ 78.004014][ T3661] __linkwatch_run_queue+0x233/0x6a0 [ 78.009496][ T3661] linkwatch_event+0x4a/0x60 [ 78.014099][ T3661] process_one_work+0x9ac/0x1680 [ 78.019034][ T3661] worker_thread+0x652/0x11c0 [ 78.023719][ T3661] kthread+0x405/0x4f0 [ 78.027810][ T3661] ret_from_fork+0x1f/0x30 [ 78.042541][ T3661] ------------[ cut here ]------------ [ 78.048253][ T3661] WARNING: CPU: 0 PID: 3661 at lib/ref_tracker.c:120 ref_tracker_free.cold+0x110/0x14e [ 78.062364][ T3661] Modules linked in: [ 78.066424][ T3661] CPU: 0 PID: 3661 Comm: kworker/0:5 Not tainted 5.16.0-rc4-next-20211210-syzkaller #0 [ 78.076075][ T3661] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 78.090648][ T3661] Workqueue: events linkwatch_event [ 78.095890][ T3661] RIP: 0010:ref_tracker_free.cold+0x110/0x14e [ 78.102191][ T3661] Code: ea 03 48 c1 e0 2a 0f b6 04 02 84 c0 74 04 3c 03 7e 4c 8b 7b 18 e8 6b 54 e9 fa e8 26 4d 57 f8 4c 89 ee 48 89 ef e8 fb 33 36 00 <0f> 0b 41 bd ea ff ff ff e9 bd 60 e9 fa 4c 89 f7 e8 16 45 a2 f8 e9 [ 78.127211][ T3661] RSP: 0018:ffffc90002b5fb18 EFLAGS: 00010246 [ 78.133684][ T3661] RAX: 0000000000000000 RBX: ffff88807467f700 RCX: 0000000000000000 [ 78.141928][ T3661] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000001 [ 78.150087][ T3661] RBP: ffff888057e105b8 R08: 0000000000000001 R09: ffffffff8ffa1967 [ 78.158211][ T3661] R10: 0000000000000001 R11: 0000000000000000 R12: 1ffff9200056bf65 [ 78.166204][ T3661] R13: 0000000000000292 R14: ffff88807467f718 R15: 00000000c0e0008c [ 78.174321][ T3661] FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 [ 78.183310][ T3661] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 78.190156][ T3661] CR2: 000000c000208800 CR3: 000000007f7b5000 CR4: 00000000003506f0 [ 78.198235][ T3661] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 78.206214][ T3661] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 78.214328][ T3661] Call Trace: [ 78.217679][ T3661] <TASK> [ 78.220621][ T3661] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70 [ 78.226981][ T3661] ? nlmsg_notify+0xbe/0x280 [ 78.231607][ T3661] ? ref_tracker_dir_exit+0x330/0x330 [ 78.237654][ T3661] ? linkwatch_do_dev+0x96/0x160 [ 78.242628][ T3661] ? __linkwatch_run_queue+0x233/0x6a0 [ 78.248170][ T3661] ? linkwatch_event+0x4a/0x60 [ 78.252946][ T3661] ? process_one_work+0x9ac/0x1680 [ 78.258136][ T3661] ? worker_thread+0x853/0x11c0 [ 78.263020][ T3661] ? kthread+0x405/0x4f0 [ 78.267905][ T3661] ? ret_from_fork+0x1f/0x30 [ 78.272670][ T3661] ? netdev_state_change+0xa1/0x130 [ 78.278019][ T3661] ? netdev_exit+0xd0/0xd0 [ 78.282466][ T3661] ? dev_activate+0x420/0xa60 [ 78.287261][ T3661] linkwatch_do_dev+0x96/0x160 [ 78.292043][ T3661] __linkwatch_run_queue+0x233/0x6a0 [ 78.297505][ T3661] ? linkwatch_do_dev+0x160/0x160 [ 78.302561][ T3661] linkwatch_event+0x4a/0x60 [ 78.307225][ T3661] process_one_work+0x9ac/0x1680 [ 78.312292][ T3661] ? pwq_dec_nr_in_flight+0x2a0/0x2a0 [ 78.317757][ T3661] ? rwlock_bug.part.0+0x90/0x90 [ 78.322726][ T3661] ? _raw_spin_lock_irq+0x41/0x50 [ 78.327844][ T3661] worker_thread+0x853/0x11c0 [ 78.332543][ T3661] ? process_one_work+0x1680/0x1680 [ 78.338500][ T3661] kthread+0x405/0x4f0 [ 78.342610][ T3661] ? set_kthread_struct+0x130/0x130 Fixes: 63f13937cbe9 ("net: linkwatch: add net device refcount tracker") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Link: https://lore.kernel.org/r/20211214051955.3569843-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Apparently a concurrent linkwatch_add_event() could
run while we are in __linkwatch_run_queue().

We need to free dev->linkwatch_dev_tracker tracker
under lweventlist_lock protection to avoid this race.

syzbot report:
[   77.935949][ T3661] reference already released.
[   77.941015][ T3661] allocated in:
[   77.944482][ T3661]  linkwatch_fire_event+0x202/0x260
[   77.950318][ T3661]  netif_carrier_on+0x9c/0x100
[   77.955120][ T3661]  __ieee80211_sta_join_ibss+0xc52/0x1590
[   77.960888][ T3661]  ieee80211_sta_create_ibss.cold+0xd2/0x11f
[   77.966908][ T3661]  ieee80211_ibss_work.cold+0x30e/0x60f
[   77.972483][ T3661]  ieee80211_iface_work+0xb70/0xd00
[   77.977715][ T3661]  process_one_work+0x9ac/0x1680
[   77.982671][ T3661]  worker_thread+0x652/0x11c0
[   77.987371][ T3661]  kthread+0x405/0x4f0
[   77.991465][ T3661]  ret_from_fork+0x1f/0x30
[   77.995895][ T3661] freed in:
[   77.999006][ T3661]  linkwatch_do_dev+0x96/0x160
[   78.004014][ T3661]  __linkwatch_run_queue+0x233/0x6a0
[   78.009496][ T3661]  linkwatch_event+0x4a/0x60
[   78.014099][ T3661]  process_one_work+0x9ac/0x1680
[   78.019034][ T3661]  worker_thread+0x652/0x11c0
[   78.023719][ T3661]  kthread+0x405/0x4f0
[   78.027810][ T3661]  ret_from_fork+0x1f/0x30
[   78.042541][ T3661] ------------[ cut here ]------------
[   78.048253][ T3661] WARNING: CPU: 0 PID: 3661 at lib/ref_tracker.c:120 ref_tracker_free.cold+0x110/0x14e
[   78.062364][ T3661] Modules linked in:
[   78.066424][ T3661] CPU: 0 PID: 3661 Comm: kworker/0:5 Not tainted 5.16.0-rc4-next-20211210-syzkaller #0
[   78.076075][ T3661] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[   78.090648][ T3661] Workqueue: events linkwatch_event
[   78.095890][ T3661] RIP: 0010:ref_tracker_free.cold+0x110/0x14e
[   78.102191][ T3661] Code: ea 03 48 c1 e0 2a 0f b6 04 02 84 c0 74 04 3c 03 7e 4c 8b 7b 18 e8 6b 54 e9 fa e8 26 4d 57 f8 4c 89 ee 48 89 ef e8 fb 33 36 00 <0f> 0b 41 bd ea ff ff ff e9 bd 60 e9 fa 4c 89 f7 e8 16 45 a2 f8 e9
[   78.127211][ T3661] RSP: 0018:ffffc90002b5fb18 EFLAGS: 00010246
[   78.133684][ T3661] RAX: 0000000000000000 RBX: ffff88807467f700 RCX: 0000000000000000
[   78.141928][ T3661] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000001
[   78.150087][ T3661] RBP: ffff888057e105b8 R08: 0000000000000001 R09: ffffffff8ffa1967
[   78.158211][ T3661] R10: 0000000000000001 R11: 0000000000000000 R12: 1ffff9200056bf65
[   78.166204][ T3661] R13: 0000000000000292 R14: ffff88807467f718 R15: 00000000c0e0008c
[   78.174321][ T3661] FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
[   78.183310][ T3661] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   78.190156][ T3661] CR2: 000000c000208800 CR3: 000000007f7b5000 CR4: 00000000003506f0
[   78.198235][ T3661] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   78.206214][ T3661] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   78.214328][ T3661] Call Trace:
[   78.217679][ T3661]  <TASK>
[   78.220621][ T3661]  ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70
[   78.226981][ T3661]  ? nlmsg_notify+0xbe/0x280
[   78.231607][ T3661]  ? ref_tracker_dir_exit+0x330/0x330
[   78.237654][ T3661]  ? linkwatch_do_dev+0x96/0x160
[   78.242628][ T3661]  ? __linkwatch_run_queue+0x233/0x6a0
[   78.248170][ T3661]  ? linkwatch_event+0x4a/0x60
[   78.252946][ T3661]  ? process_one_work+0x9ac/0x1680
[   78.258136][ T3661]  ? worker_thread+0x853/0x11c0
[   78.263020][ T3661]  ? kthread+0x405/0x4f0
[   78.267905][ T3661]  ? ret_from_fork+0x1f/0x30
[   78.272670][ T3661]  ? netdev_state_change+0xa1/0x130
[   78.278019][ T3661]  ? netdev_exit+0xd0/0xd0
[   78.282466][ T3661]  ? dev_activate+0x420/0xa60
[   78.287261][ T3661]  linkwatch_do_dev+0x96/0x160
[   78.292043][ T3661]  __linkwatch_run_queue+0x233/0x6a0
[   78.297505][ T3661]  ? linkwatch_do_dev+0x160/0x160
[   78.302561][ T3661]  linkwatch_event+0x4a/0x60
[   78.307225][ T3661]  process_one_work+0x9ac/0x1680
[   78.312292][ T3661]  ? pwq_dec_nr_in_flight+0x2a0/0x2a0
[   78.317757][ T3661]  ? rwlock_bug.part.0+0x90/0x90
[   78.322726][ T3661]  ? _raw_spin_lock_irq+0x41/0x50
[   78.327844][ T3661]  worker_thread+0x853/0x11c0
[   78.332543][ T3661]  ? process_one_work+0x1680/0x1680
[   78.338500][ T3661]  kthread+0x405/0x4f0
[   78.342610][ T3661]  ? set_kthread_struct+0x130/0x130

Fixes: 63f13937cbe9 ("net: linkwatch: add net device refcount tracker")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Link: https://lore.kernel.org/r/20211214051955.3569843-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>