* Re: [PATCH net 4/4] selftests: bonding: add a test for VLAN propagation over a bonded real device
From: Stanislav Fomichev @ 2026-06-25 15:49 UTC (permalink / raw)
To: Jakub Kicinski
Cc: davem, netdev, edumazet, pabeni, andrew+netdev, horms, jv, sdf,
dongchenchen2, idosch, n05ec, yuantan098, kuniyu, nb,
aleksandr.loktionov, dtatulea
In-Reply-To: <20260624182018.2445732-5-kuba@kernel.org>
On 06/24, Jakub Kicinski wrote:
> Add a regression test for the VLAN notifier handling that the netdev_work
> deferral fixed.
>
> A VLAN's real device propagates its UP/DOWN, MTU and feature changes onto
> the VLANs stacked on top of it. This used to be done synchronously from the
> real device's notifier and deadlocked when the real device was brought up
> while enslaved to a bond (instance lock held across NETDEV_UP) and the VLAN
> on top was itself a bond member: the synchronous propagation re-entered the
> stack and took the same instance lock again.
>
> The test covers both halves:
> - that the deferred UP/DOWN, MTU and feature propagation actually lands on
> the VLAN (link state and MTU use an ops-locked dummy, i.e. the deferral
> path; features use veth, which exports vlan_features to inherit), and
> - that the deadlock-prone topology - a VLAN on a dummy, with the VLAN and
> the dummy each enslaved to a different bond - can be built without
> hanging.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
^ permalink raw reply
* Re: [PATCH net 3/4] vlan: defer real device state propagation to netdev_work
From: Stanislav Fomichev @ 2026-06-25 15:49 UTC (permalink / raw)
To: Jakub Kicinski
Cc: davem, netdev, edumazet, pabeni, andrew+netdev, horms, jv, sdf,
dongchenchen2, idosch, n05ec, yuantan098, kuniyu, nb,
aleksandr.loktionov, dtatulea, syzbot+09da62a8b78959ceb8bb,
syzbot+cb67c392b0b8f0fd0fc1, syzbot+9bb8bd77f3966641f298
In-Reply-To: <20260624182018.2445732-4-kuba@kernel.org>
On 06/24, Jakub Kicinski wrote:
> vlan_device_event() generates nested UP/DOWN, MTU and feature
> change events. It executes an event for the VLAN device directly
> from the notifier - while the locks of the lower device are held.
>
> This causes deadlocks, for example:
>
> bond (3) bond_update_speed_duplex(vlan)
> | ^ v
> vlan (2) UP(vlan) (4) vlan_ethtool_get_link_ksettings()
> | ^ v
> dummy (1) UP(dummy) (5) __ethtool_get_link_ksettings()
>
> The dummy device is ops locked, vlan creates a nested event (2),
> then bond wants to ask vlan for link state (3). bond uses the
> "I'm already holding the instance lock" flavor of API. But in
> this case the lock held refers to vlan itself. We hit vlan's
> link settings trampoline (4) and call __ethtool_get_link_ksettings()
> which tries to lock dummy. Deadlock. There's no clean way for us
> to tell the vlan_ethtool_get_link_ksettings() that the caller
> is already in lower device's critical section.
>
> Defer the propagation to the per-netdev work facility instead:
> the notifier only schedules netdev_work_sched(vlandev, VLAN_WORK_*),
> and ndo_work (vlan_dev_work) applies the change later. Hopefully
> nobody expects the VLAN state changes to be instantaneous.
>
> If someone does expect the changes to be instantaneous we will
> have to do the same thing Stan did for rx_mode and "strategically"
> place sync calls, to make sure such delayed works are executed
> after we drop the ops lock but before we drop rtnl_lock.
>
> Stan suggests that if we need that down the line we may
> consider reshaping the mechanism into "async notifications".
> AFAICT only vlan does this sort of netdev open chaining,
> so as a first try I think that sticking the complexity into
> the vlan code makes sense.
>
> One corner case is that we need to cancel the event if user
> explicitly changes the state before work could run. Consider
> the following operations with vlan0 on top of dummy0:
>
> ip link set dev dummy0 up # queues work to up vlan0
> ip link set dev vlan0 down # user explicitly downs the vlan
> ndo_work # acts on the stale event
>
> Reported-by: syzbot+09da62a8b78959ceb8bb@syzkaller.appspotmail.com
> Reported-by: syzbot+cb67c392b0b8f0fd0fc1@syzkaller.appspotmail.com
> Reported-by: syzbot+9bb8bd77f3966641f298@syzkaller.appspotmail.com
> Fixes: 9f275c2e9020 ("net: ethtool: make sure __ethtool_get_link_ksettings() is ops-locked")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
^ permalink raw reply
* Re: [PATCH net 2/4] net: add the driver-facing netdev_work scheduling API
From: Stanislav Fomichev @ 2026-06-25 15:48 UTC (permalink / raw)
To: Jakub Kicinski
Cc: davem, netdev, edumazet, pabeni, andrew+netdev, horms, jv, sdf,
dongchenchen2, idosch, n05ec, yuantan098, kuniyu, nb,
aleksandr.loktionov, dtatulea
In-Reply-To: <20260624182018.2445732-3-kuba@kernel.org>
On 06/24, Jakub Kicinski wrote:
> With an extra event mask we can easily extend the netdev work
> to also service driver-defined events. For advanced drivers
> this is probably not a perfect match, but it makes running
> deferred work easier in simple cases.
>
> Expose the netdev_work facility to drivers. Add helpers
> to schedule work and a dedicated ndo to perform the driver-
> -scheduled actions.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
^ permalink raw reply
* Re: [PATCH net 1/4] net: turn the rx_mode work into a generic netdev_work facility
From: Stanislav Fomichev @ 2026-06-25 15:48 UTC (permalink / raw)
To: Jakub Kicinski
Cc: davem, netdev, edumazet, pabeni, andrew+netdev, horms, jv, sdf,
dongchenchen2, idosch, n05ec, yuantan098, kuniyu, nb,
aleksandr.loktionov, dtatulea
In-Reply-To: <20260624182018.2445732-2-kuba@kernel.org>
On 06/24, Jakub Kicinski wrote:
> The rx_mode update runs from a workqueue: drivers have their
> ndo_set_rx_mode_async() callback executed by a single global
> work item under RTNL and ops lock. This is a useful pattern.
>
> Support multiple "events" that need to be serviced and make RX_MODE
> sync the first one. Call the events "core" because later on
> we will let drivers define and schedule their own.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
^ permalink raw reply
* Re: [PATCH net] net: ethtool: keep rtnl_lock for ops using ethtool_op_get_link()
From: Stanislav Fomichev @ 2026-06-25 15:48 UTC (permalink / raw)
To: Jakub Kicinski
Cc: davem, netdev, edumazet, pabeni, andrew+netdev, horms,
Breno Leitao, joshwash, hramamurthy, anthony.l.nguyen,
przemyslaw.kitszel, saeedm, tariqt, mbloch, leon, alexanderduyck,
kernel-team, kys, haiyangz, wei.liu, decui, longli, jordanrhee,
jacob.e.keller, nktgrg, debarghyak, mohsin.bashr, ernis, sdf, gal,
linux-rdma, linux-hyperv
In-Reply-To: <20260624190439.2521219-1-kuba@kernel.org>
On 06/24, Jakub Kicinski wrote:
> Breno reports following splats on mlx5:
>
> RTNL: assertion failed at net/core/dev.c (2241)
> WARNING: net/core/dev.c:2241 at netif_state_change+0xed/0x130, CPU#5: ethtool/1335
> RIP: 0010:netif_state_change+0xf9/0x130
> Call Trace:
> <TASK>
> __linkwatch_sync_dev+0xea/0x120
> ethtool_op_get_link+0xe/0x20
> __ethtool_get_link+0x26/0x40
> linkstate_prepare_data+0x51/0x200
> ethnl_default_doit+0x213/0x470
> genl_family_rcv_msg_doit+0xdd/0x110
>
> Looks like I missed ethtool_op_get_link() trying to sync linkwatch,
> which needs rtnl_lock. Not all drivers do this - bnxt doesn't,
> it just returns the link state, so add an opt-in bit.
>
> Reported-by: Breno Leitao <leitao@debian.org>
> Fixes: 45079e00133e ("net: ethtool: optionally skip rtnl_lock on Netlink path for GET ops")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
^ permalink raw reply
* [PATCH net] eth: fbnic: don't cache shinfo across skb realloc
From: Jakub Kicinski @ 2026-06-25 16:05 UTC (permalink / raw)
To: davem
Cc: netdev, edumazet, pabeni, andrew+netdev, horms, Jakub Kicinski,
Alexander Duyck, kernel-team, mohsin.bashr
fbnic_tx_lso() calls skb_cow_head() which may reallocate the skb
including the shared info. We can't use the pointer calculated
before the call.
BUG: KASAN: slab-use-after-free in fbnic_tx_lso.isra.0+0x668/0x8e0
Read of size 4 at addr ff110000262edd98 by task swapper/5/0
Call Trace:
fbnic_tx_lso.isra.0+0x668/0x8e0
fbnic_xmit_frame+0x622/0xba0
dev_hard_start_xmit+0xf4/0x620
Allocated by task 8653:
__alloc_skb+0x11e/0x5f0
alloc_skb_with_frags+0xcc/0x6c0
sock_alloc_send_pskb+0x327/0x3f0
__ip_append_data+0x188b/0x47a0
ip_make_skb+0x24a/0x300
udp_sendmsg+0x14d2/0x21e0
Freed by task 0:
kfree+0x123/0x5a0
pskb_expand_head+0x36c/0xfa0
fbnic_tx_lso.isra.0+0x500/0x8e0
fbnic_xmit_frame+0x622/0xba0
dev_hard_start_xmit+0xf4/0x620
sch_direct_xmit+0x25b/0x1100
The buggy address belongs to the object at ff110000262edc40
which belongs to the cache skbuff_small_head of size 640
The buggy address is located 344 bytes inside of
freed 640-byte region [ff110000262edc40, ff110000262ede
Link: https://netdev.bots.linux.dev/logs/vmksft/fbnic-qemu-dbg/results/705762/15-uso-py/stderr
Fixes: b0b0f52042ac ("eth: fbnic: support TCP segmentation offload")
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: kernel-team@meta.com
CC: mohsin.bashr@gmail.com
---
drivers/net/ethernet/meta/fbnic/fbnic_txrx.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
index 9cd85a0d0c3a..401f8b8ae1ca 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
@@ -194,16 +194,18 @@ static bool fbnic_tx_tstamp(struct sk_buff *skb)
static bool
fbnic_tx_lso(struct fbnic_ring *ring, struct sk_buff *skb,
- struct skb_shared_info *shinfo, __le64 *meta,
- unsigned int *l2len, unsigned int *i3len)
+ __le64 *meta, unsigned int *l2len, unsigned int *i3len)
{
unsigned int l3_type, l4_type, l4len, hdrlen;
+ struct skb_shared_info *shinfo;
unsigned char *l4hdr;
__be16 payload_len;
if (unlikely(skb_cow_head(skb, 0)))
return true;
+ shinfo = skb_shinfo(skb);
+
if (shinfo->gso_type & SKB_GSO_PARTIAL) {
l3_type = FBNIC_TWD_L3_TYPE_OTHER;
} else if (!skb->encapsulation) {
@@ -258,7 +260,6 @@ fbnic_tx_lso(struct fbnic_ring *ring, struct sk_buff *skb,
static bool
fbnic_tx_offloads(struct fbnic_ring *ring, struct sk_buff *skb, __le64 *meta)
{
- struct skb_shared_info *shinfo = skb_shinfo(skb);
unsigned int l2len, i3len;
if (fbnic_tx_tstamp(skb))
@@ -273,8 +274,8 @@ fbnic_tx_offloads(struct fbnic_ring *ring, struct sk_buff *skb, __le64 *meta)
*meta |= cpu_to_le64(FIELD_PREP(FBNIC_TWD_CSUM_OFFSET_MASK,
skb->csum_offset / 2));
- if (shinfo->gso_size) {
- if (fbnic_tx_lso(ring, skb, shinfo, meta, &l2len, &i3len))
+ if (skb_is_gso(skb)) {
+ if (fbnic_tx_lso(ring, skb, meta, &l2len, &i3len))
return true;
} else {
*meta |= cpu_to_le64(FBNIC_TWD_FLAG_REQ_CSO);
--
2.54.0
^ permalink raw reply related
* Re: [PATCH net-next] Documentation: networking: Add a test plan for ethtool pause validation
From: Maxime Chevallier @ 2026-06-25 16:03 UTC (permalink / raw)
To: Andrew Lunn
Cc: Jakub Kicinski, davem, Eric Dumazet, Paolo Abeni, Simon Horman,
Russell King, Heiner Kallweit, Jonathan Corbet, Shuah Khan,
Oleksij Rempel, Vladimir Oltean, Florian Fainelli,
thomas.petazzoni, netdev, linux-kernel, linux-doc
In-Reply-To: <dfee1484-fa2a-4b98-af5a-1e67ac716905@lunn.ch>
>
> Does it even make sense to advertise this when in HD? But i don't
> think we need to consider this now. I consider HD low priority, i
> doubt it is actually used very often. We should concentrate on FD
> testing.
That's fine by me as well, let's keep it simple, we may revisit that if
we really need to.
>
>> # ethtool -a eth2
>> Autonegotiate: on
>> RX: off
>> TX: off
>> RX negotiated: on
>> TX negotiated: on
>>
>>
>> Sure, pause and HD don't make sense, however what I find confusing to some
>> extent is that the only place we have information about the *actual* pause
>> settings is the "link is Up" log in dmesg.
>
> Maybe we should extend ksetting get to return the resolved pause
> parameters? But i'm not sure how much that actually gives us. Anything
> using phylink will just ask phylink to fill in the ksettings
> information, and it seems unlikely phylink gets it wrong. What we are
> really trying to test is drivers which don't user phylink, those are
> the ones which are generally broken, and they are not going to
> implement anything new in ksettings.
Correct yes. If the MAC driver uses phylink and a test fails, it very likely
means that the PHY driver is doing shady stuff (and some are/were for pause)
> So i think the test has to look
> at:
>
>> Advertised pause frame use: Symmetric Receive-only
>> Link partner advertised pause frame use: Symmetric Receive-only
>
> and check these match what we expect.
All good for me :) thanks for you feedback,
Maxime
^ permalink raw reply
* [PATCH v3 4/4] vhost/vsock: add VHOST_RESET_OWNER ioctl
From: Andrey Drobyshev @ 2026-06-25 15:54 UTC (permalink / raw)
To: linux-kernel
Cc: kvm, virtualization, netdev, sgarzare, mst, stefanha,
dongli.zhang, maciej.szmigiero, bchaney, mark.kanda, ptikhomirov,
den, andrey.drobyshev
In-Reply-To: <20260625155416.480669-1-andrey.drobyshev@virtuozzo.com>
From: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
This ioctl is needed for QEMU's CPR (checkpoint-restore) migration of
the guest with vhost-vsock device. For this to work, we need to reset
the device ownership on the source side by calling RESET_OWNER, and then
claim it on the dest side by calling SET_OWNER. We expect not to lose any
AF_VSOCK connection while this happens.
RESET_OWNER keeps the guest CID hashed, so that connections survive. That
leaves the device reachable by a lockless send/cancel path while the worker
is being torn down: a concurrent vhost_transport_send_pkt() or
vhost_transport_cancel_pkt() can call vhost_vq_work_queue() as
vhost_workers_free() frees the worker. That might cause a use-after-free
of vq->worker. In addition, any work queued onto the dying worker leaves
VHOST_WORK_QUEUED stuck, stalling send_pkt_queue after resume.
Fence the send/cancel paths around the teardown: send_pkt()/cancel_pkt()
only kick the worker while the backend is alive. And reset_owner() calls
synchronize_rcu() after drop_backends() so in-flight send/cancel finish
before the worker is freed.
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
drivers/vhost/vsock.c | 51 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 49 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 81d4f7209719..f0a0aa7d3200 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -318,7 +318,14 @@ vhost_transport_send_pkt(struct sk_buff *skb, struct net *net)
atomic_inc(&vsock->queued_replies);
virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
- vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX], &vsock->send_pkt_work);
+
+ /* Skip the kick once the backend is gone (stop/RESET_OWNER); the skb
+ * stays queued and vhost_vsock_start() drains it. Pairs with the
+ * synchronize_rcu() in vhost_vsock_reset_owner().
+ */
+ if (data_race(vhost_vq_get_backend(&vsock->vqs[VSOCK_VQ_RX])))
+ vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX],
+ &vsock->send_pkt_work);
rcu_read_unlock();
return len;
@@ -346,7 +353,15 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk)
int new_cnt;
new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
- if (new_cnt + cnt >= tx_vq->num && new_cnt < tx_vq->num)
+
+ /* Skip the kick once the backend is gone (stop/RESET_OWNER):
+ * vhost_poll_queue() would touch the worker which is being freed
+ * by teardown, e.g. on RESET_OWNER. Pairs with the
+ * synchronize_rcu() in vhost_vsock_reset_owner(). The TX VQ is
+ * re-kicked by vhost_vsock_start().
+ */
+ if (data_race(vhost_vq_get_backend(tx_vq)) &&
+ new_cnt + cnt >= tx_vq->num && new_cnt < tx_vq->num)
vhost_poll_queue(&tx_vq->poll);
}
@@ -903,6 +918,36 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
return -EFAULT;
}
+static int vhost_vsock_reset_owner(struct vhost_vsock *vsock)
+{
+ struct vhost_iotlb *umem;
+ long err;
+
+ mutex_lock(&vsock->dev.mutex);
+ err = vhost_dev_check_owner(&vsock->dev);
+ if (err)
+ goto done;
+ umem = vhost_dev_reset_owner_prepare();
+ if (!umem) {
+ err = -ENOMEM;
+ goto done;
+ }
+ vhost_vsock_drop_backends(vsock);
+
+ /* Let in-flight send_pkt() callers stop touching the worker before the
+ * flush + free below. Pairs with the backend check in
+ * vhost_transport_send_pkt().
+ */
+ synchronize_rcu();
+
+ vhost_vsock_flush(vsock);
+ vhost_dev_stop(&vsock->dev);
+ vhost_dev_reset_owner(&vsock->dev, umem);
+done:
+ mutex_unlock(&vsock->dev.mutex);
+ return err;
+}
+
static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
unsigned long arg)
{
@@ -946,6 +991,8 @@ static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
return -EOPNOTSUPP;
vhost_set_backend_features(&vsock->dev, features);
return 0;
+ case VHOST_RESET_OWNER:
+ return vhost_vsock_reset_owner(vsock);
default:
mutex_lock(&vsock->dev.mutex);
r = vhost_dev_ioctl(&vsock->dev, ioctl, argp);
--
2.47.1
^ permalink raw reply related
* [PATCH v3 3/4] vhost/vsock: re-scan TX virtqueue on device start
From: Andrey Drobyshev @ 2026-06-25 15:54 UTC (permalink / raw)
To: linux-kernel
Cc: kvm, virtualization, netdev, sgarzare, mst, stefanha,
dongli.zhang, maciej.szmigiero, bchaney, mark.kanda, ptikhomirov,
den, andrey.drobyshev
In-Reply-To: <20260625155416.480669-1-andrey.drobyshev@virtuozzo.com>
During QEMU CPR live-update (and VHOST_RESET_OWNER in general) the guest
keeps running while the host drops and later re-attaches vhost backends.
If the guest adds a buffer to the TX virtqueue (guest->host) and kicks
while the backend is temporarily NULL (between vhost_vsock_drop_backends()
and the next vhost_vsock_start()), then the kick is delivered to the
vhost worker, handle_tx_kick() sees a NULL backend and returns, and the
kick signal is consumed. The buffer is then left in the ring.
Then upon device start vhost_vsock_start() only re-kicks the RX send
worker, never the TX VQ, so the buffer is processed only if the guest
happens to kick again. But if the guest itself is now waiting for data
from the host, it will never kick TX VQ again, and we end up in a
deadlock.
The issue itself is pre-existing, but it only manifests during a brief
pause caused by VHOST_RESET_OWNER. Namely, the deadlock is reproduced
during active host->guest socat data transfer under multiple consecutive
CPR live-update's.
To fix this, in vhost_vsock_start(), after kicking the RX send worker, also
queue the TX vq poll so any buffers the guest enqueued while we were paused
get scanned.
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
---
drivers/vhost/vsock.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index bec6bcfd885f..81d4f7209719 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -646,6 +646,13 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
*/
vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX], &vsock->send_pkt_work);
+ /*
+ * Some packets might've also been queued in TX VQ. That is the case
+ * during the brief device pause caused by VHOST_RESET_OWNER. Re-scan
+ * the TX VQ here, mirroring the RX send-worker kick above.
+ */
+ vhost_poll_queue(&vsock->vqs[VSOCK_VQ_TX].poll);
+
mutex_unlock(&vsock->dev.mutex);
return 0;
--
2.47.1
^ permalink raw reply related
* [PATCH v3 2/4] vhost/vsock: suppress EHOSTUNREACH fast-fail during CPR pause
From: Andrey Drobyshev @ 2026-06-25 15:54 UTC (permalink / raw)
To: linux-kernel
Cc: kvm, virtualization, netdev, sgarzare, mst, stefanha,
dongli.zhang, maciej.szmigiero, bchaney, mark.kanda, ptikhomirov,
den, andrey.drobyshev
In-Reply-To: <20260625155416.480669-1-andrey.drobyshev@virtuozzo.com>
Earlier commit bb26ed5f3a8b ("vhost/vsock: Refuse the connection
immediately when guest isn't ready") added a fast-fail in
vhost_transport_send_pkt(). It rejects every host send with -EHOSTUNREACH
until the destination calls SET_RUNNING(1). The fast-fail condition checks
whether device's backends are dropped, and if they're, the guest is
considered to be not ready.
However, there might be other reasons for backends to be nulled. In
particular, when QEMU is performing CPR (checkpoint-restore) migration,
device ownership is being RESET and SET again, which leads to backends
drop and reattach. If we end up connecting during this window, an
AF_VSOCK client gets -EHOSTUNREACH, which is wrong.
Add a 'started' flag which is set once in vhost_vsock_start() and is
never cleared. The behaviour changes to:
* When device was never started -> flag is unset -> no listener can
exist yet -> fast-fail;
* Once the device starts -> flag is set -> we don't fast-fail ->
we queue and preserve during any later stop / CPR pause.
Important caveat: after the first start, a connect during any stopped
window is queued instead of fast-failed. That was the behaviour before
the patch bb26ed5f3a8b, and we're restoring it now. However we still
keep the behaviour originally intended by that commit (i.e. fast-fail if
there's no real listener yet) while fixing the CPR path.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
---
drivers/vhost/vsock.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index b12221ce6faf..bec6bcfd885f 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -61,6 +61,7 @@ struct vhost_vsock {
u32 guest_cid;
bool seqpacket_allow;
+ bool started; /* set on first SET_RUNNING(1); never cleared */
};
static u32 vhost_transport_get_local_cid(void)
@@ -302,17 +303,12 @@ vhost_transport_send_pkt(struct sk_buff *skb, struct net *net)
return -ENODEV;
}
- /* Fast-fail if the guest hasn't enabled the RX vq yet. Queuing the packet
- * and making the caller wait is pointless: even if the guest manages to init
- * within the timeout, it'll immediately reply with RST, because there's no
- * listener on the port yet.
- *
- * vhost_vq_get_backend() without vq->mutex is acceptable here: locking
- * the mutex would be too expensive in this hot path, and we already have
- * all the outcomes covered: if the backend becomes NULL right after the check,
- * vhost_transport_do_send_pkt() will check it under the mutex anyway.
+ /* Fast-fail until the guest first enables the device (SET_RUNNING(1)).
+ * Before that there is no listener, so queuing is pointless. 'started'
+ * is never cleared, so once we're up we keep queuing across later
+ * stop / CPR-pause windows.
*/
- if (unlikely(!data_race(vhost_vq_get_backend(&vsock->vqs[VSOCK_VQ_RX])))) {
+ if (unlikely(!READ_ONCE(vsock->started))) {
rcu_read_unlock();
kfree_skb(skb);
return -EHOSTUNREACH;
@@ -640,6 +636,11 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
mutex_unlock(&vq->mutex);
}
+ /* Set 'started' flag on the first start; never cleared, so send_pkt
+ * keeps queuing (instead of fast-failing) on later stop / CPR pauses.
+ */
+ WRITE_ONCE(vsock->started, true);
+
/* Some packets may have been queued before the device was started,
* let's kick the send worker to send them.
*/
@@ -728,6 +729,7 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
vsock->guest_cid = 0; /* no CID assigned yet */
vsock->seqpacket_allow = false;
+ vsock->started = false;
atomic_set(&vsock->queued_replies, 0);
--
2.47.1
^ permalink raw reply related
* Re: [PATCH iproute2-next] "ip help" wrong output, exit code.
From: Dmitri Seletski @ 2026-06-25 15:54 UTC (permalink / raw)
Cc: netdev
In-Reply-To: <3d6f256c-3bd0-441a-bece-8692985c5ddc@gmail.com>
I am confused.
Whats the next step here?
Regards
Dmitri
On 6/22/26 18:47, Dmitri Seletski wrote:
> Hello David,
>
>
> Based on change introduced:
>
> Two samples of "ip help" with demonstration of exit code and standard
> output are below.
>
> This is in line with what expect.
>
>
> dimkosPC~/compiled/iproute2-next #if ./ip/ip help a >>/dev/null ;
> then echo help triggered ; else echo error code triggered ;fi #this
> redirects standard output to /dev/null, so text missing is not error,
> but standard text
> help triggered
>
> dimkosPC~/compiled/iproute2-next #if ./ip/ip help ; then echo help
> triggered ; else echo error code triggered ;fi
> Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
> ip [ -force ] -batch filename
> where OBJECT := { address | addrlabel | fou | help | ila | ioam |
> l2tp | link |
> macsec | maddress | monitor | mptcp | mroute | mrule |
> neighbor | neighbour | netconf | netns | nexthop |
> ntable |
> ntbl | route | rule | sr | stats | tap | tcpmetrics |
> token | tunnel | tuntap | vrf | xfrm }
> OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |
> -h[uman-readable] | -iec | -j[son] | -p[retty] |
> -f[amily] { inet | inet6 | mpls | bridge | link } |
> -4 | -6 | -M | -B | -0 |
> -l[oops] { maximum-addr-flush-attempts } | -echo |
> -br[ief] |
> -o[neline] | -t[imestamp] | -ts[hort] | -b[atch]
> [filename] |
> -rc[vbuf] [size] | -n[etns] name | -N[umeric] |
> -a[ll] |
> -c[olor]}
> help triggered
>
> Two samples of command that is broken on purpose.
>
> dimkosPC~/compiled/iproute2-next #if ./ip/ip idontexist ; then echo
> help triggered ; else echo error code triggered ;fi
> Object "idontexist" is unknown, try "ip help".
> error code triggered
>
> dimkosPC~/compiled/iproute2-next #if ./ip/ip idontexist >>/dev/null
> ; then echo help triggered ; else echo error code triggered ;fi
> #this redirects standard output to /dev/null, so text missing is not
> error, but standard text
> Object "idontexist" is unknown, try "ip help".
> error code triggered
>
> This works as expected as per my understanding.
>
>
> Not everything is fixed, but chunk of things fixed is better than non
> of it.
>
> for example:
>
> if ip add help ; then echo help triggered ; else echo error code
> triggered ;fi #this redirects standard output to /dev/null, so text
> missing is not error, but standard text
> Usage: ip address {add|change|replace} IFADDR dev IFNAME [ LIFETIME ]
> [ CONFFLAG-LIST ]
> ip address del IFADDR dev IFNAME [mngtmpaddr]
> ip address {save|flush} [ dev IFNAME ] [ scope SCOPE-ID ] [ to
> PREFIX ]
> [ FLAG-LIST ] [ label LABEL ] [ { up | down
> } ]
> ip address [ show [ dev IFNAME ] [ scope SCOPE-ID ] [ master
> DEVICE ]
> [ nomaster ]
> [ type TYPE ] [ to PREFIX ] [ FLAG-LIST ]
> [ label LABEL ] [ { up | down } ] [ vrf NAME ]
> [ proto ADDRPROTO ] ]
> ip address {showdump|restore}
> IFADDR := PREFIX | ADDR peer PREFIX
> [ broadcast ADDR ] [ anycast ADDR ]
> [ label IFNAME ] [ scope SCOPE-ID ] [ metric METRIC ]
> [ proto ADDRPROTO ]
> SCOPE-ID := [ host | link | global | NUMBER ]
> FLAG-LIST := [ FLAG-LIST ] FLAG
> FLAG := [ permanent | dynamic | secondary | primary |
> [-]tentative | [-]deprecated | [-]dadfailed | temporary |
> CONFFLAG-LIST ]
> CONFFLAG-LIST := [ CONFFLAG-LIST ] CONFFLAG
> CONFFLAG := [ home | nodad | mngtmpaddr | noprefixroute | autojoin ]
> LIFETIME := [ valid_lft LFT ] [ preferred_lft LFT ]
> LFT := forever | SECONDS
> ADDRPROTO := [ NAME | NUMBER ]
> TYPE := { amt | bareudp | bond | bond_slave | bridge | bridge_slave |
> dsa | dummy | erspan | geneve | gre | gretap | gtp | hsr |
> ifb | ip6erspan | ip6gre | ip6gretap | ip6tnl |
> ipip | ipoib | ipvlan | ipvtap |
> macsec | macvlan | macvtap | netdevsim |
> netkit | nlmon | pfcp | rmnet | sit | team | team_slave |
> vcan | veth | vlan | vrf | vti | vxcan | vxlan | wwan |
> xfrm | virt_wifi }
> error code triggered
>
> This is still problematic.
>
>
> But so far code leaves "ip help" command/argument in better shape than
> it found it in.
>
>
> I may try improve things more, but lets submit what we already have
> "better", please.
>
> Kind Regards
>
> Dmitri Seletski
>
>
> On 6/22/26 17:44, David Laight wrote:
>> On Mon, 22 Jun 2026 07:57:00 -0700
>> Stephen Hemminger <stephen@networkplumber.org> wrote:
>>
>>> On Sun, 21 Jun 2026 22:48:59 +0100
>>> Dmitri Seletski <drjoms@gmail.com> wrote:
>>>
>>>> From 0805e07105cd15c5b94271a4706e50e3c65dbde5 Mon Sep 17 00:00:00
>>>> 2001
>>>> From: Dmitri Seletski <drjoms@gmail.com>
>>>> Date: Sun, 21 Jun 2026 22:12:43 +0100
>>>> Subject: [PATCH iproute2-next] "ip help" wrong output, exit code.
>>>>
>>>> Changed output of "ip help" from standard error to standard output.
>>>> And
>>>> Exit is now 0 instead of -1. "ip help|grep bridge" - now gives bridge
>>>> syntax instead of flooding user with everything from "ip help".
>>>> ---
>>>> ip/ip.c | 4 ++--
>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/ip/ip.c b/ip/ip.c
>>>> index e4b71bde..4627b61c 100644
>>>> --- a/ip/ip.c
>>>> +++ b/ip/ip.c
>>>> @@ -56,7 +56,7 @@ static void usage(void) __attribute__((noreturn));
>>>>
>>>> static void usage(void)
>>>> {
>>>> -fprintf(stderr,
>>>> +fprintf(stdout,
>>>> "Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }\n"
>>>> " ip [ -force ] -batch filename\n"
>>>> "where OBJECT := { address | addrlabel | fou | help | ila | ioam |
>>>> l2tp
>>>> | link |\n"
>>>> @@ -72,7 +72,7 @@ static void usage(void)
>>>> " -o[neline] | -t[imestamp] | -ts[hort] | -b[atch]
>>>> [filename] |\n"
>>>> " -rc[vbuf] [size] | -n[etns] name | -N[umeric] |
>>>> -a[ll] |\n"
>>>> " -c[olor]}\n");
>>>> -exit(-1);
>>>> +exit(0);
>>>> }
>>> Your mailer damages white space.
>>>
>> The output also needs to depend on whether these is a 'usage' error or
>> if 'help' is requested.
>> Code code is correct for the former - except it should do exit(1).
>>
>> David
>>
>>
^ permalink raw reply
* [PATCH v3 1/4] vhost/vsock: split out vhost_vsock_drop_backends helper
From: Andrey Drobyshev @ 2026-06-25 15:54 UTC (permalink / raw)
To: linux-kernel
Cc: kvm, virtualization, netdev, sgarzare, mst, stefanha,
dongli.zhang, maciej.szmigiero, bchaney, mark.kanda, ptikhomirov,
den, andrey.drobyshev
In-Reply-To: <20260625155416.480669-1-andrey.drobyshev@virtuozzo.com>
From: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Split the actual backend dropping part from vhost_vsock_stop. We're
going to need it for the VHOST_RESET_OWNER implementation in the
following patch, when vsock->dev.mutex is already taken and owner is
checked.
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
---
drivers/vhost/vsock.c | 26 +++++++++++++++++---------
1 file changed, 17 insertions(+), 9 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 9aaab6bb8061..b12221ce6faf 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -664,9 +664,24 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
return ret;
}
-static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
+static void vhost_vsock_drop_backends(struct vhost_vsock *vsock)
{
+ struct vhost_virtqueue *vq;
size_t i;
+
+ lockdep_assert_held(&vsock->dev.mutex);
+
+ for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
+ vq = &vsock->vqs[i];
+
+ mutex_lock(&vq->mutex);
+ vhost_vq_set_backend(vq, NULL);
+ mutex_unlock(&vq->mutex);
+ }
+}
+
+static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
+{
int ret = 0;
mutex_lock(&vsock->dev.mutex);
@@ -677,14 +692,7 @@ static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
goto err;
}
- for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
- struct vhost_virtqueue *vq = &vsock->vqs[i];
-
- mutex_lock(&vq->mutex);
- vhost_vq_set_backend(vq, NULL);
- mutex_unlock(&vq->mutex);
- }
-
+ vhost_vsock_drop_backends(vsock);
err:
mutex_unlock(&vsock->dev.mutex);
return ret;
--
2.47.1
^ permalink raw reply related
* [PATCH v3 0/4] vhost/vsock: add support for VHOST_RESET_OWNER and CPR migration
From: Andrey Drobyshev @ 2026-06-25 15:54 UTC (permalink / raw)
To: linux-kernel
Cc: kvm, virtualization, netdev, sgarzare, mst, stefanha,
dongli.zhang, maciej.szmigiero, bchaney, mark.kanda, ptikhomirov,
den, andrey.drobyshev
v2 -> v3:
* Patch 4: skip the kick of TX VQ worker once backend is gone - add
to cancel_pkt() the same guard as in send_pkt().
(Reported by Sashiko AI)
v2: https://lore.kernel.org/virtualization/20260622175808.508084-1-andrey.drobyshev@virtuozzo.com
Andrey Drobyshev (2):
vhost/vsock: suppress EHOSTUNREACH fast-fail during CPR pause
vhost/vsock: re-scan TX virtqueue on device start
Pavel Tikhomirov (2):
vhost/vsock: split out vhost_vsock_drop_backends helper
vhost/vsock: add VHOST_RESET_OWNER ioctl
drivers/vhost/vsock.c | 106 +++++++++++++++++++++++++++++++++---------
1 file changed, 85 insertions(+), 21 deletions(-)
--
2.47.1
^ permalink raw reply
* Re: [Regression] Broken MPLS routes with multiple nexthops
From: Kuniyuki Iwashima @ 2026-06-25 15:51 UTC (permalink / raw)
To: anthony.doeraene; +Cc: davem, kuniyu, netdev
In-Reply-To: <036a0c95-f5d4-46ab-88e7-1eab567d7a84@uclouvain.be>
From: Anthony Doeraene <anthony.doeraene@uclouvain.be>
Date: Thu, 25 Jun 2026 17:07:41 +0200
> Hello all,
>
> According to my experiments, it seems that ECMP with MPLS (i.e. an MPLS
> route with multiple
> nexthops) is broken on the master branch of the kernel.
>
> Indeed, whenever adding an MPLS route with multiple nexthops, ip route
> show the route as
> a dead route/link down, even if nexthops are reachable.
>
> Example to reproduce the error (tested with virtme-ng and the master
> branch of the kernel):
> ```
> modprobe mpls_iptunnel mpls_router
> sysctl net.mpls.platform_labels=100000
> ip link set dummy0 up
> ip addr add fc00:1::1/112 dev dummy0
> ip addr add fc00:2::1/112 dev dummy0
> ip -M route add 16000 \
> nexthop via inet6 fc00:1::2 as 16001 \
> nexthop via inet6 fc00:2::2 as 16002
>
> # Check the route
> ip -M route
> # Output:
> # 16000 dead linkdown
> #
> # Route is not present, even if accepted
> ```
>
> From a git blame, it seems that commit
> f0914b8436c589b7ab32c614d8d7868eb4ebd5bf
> broke the core logic for building nexthops.
Thanks for the report !
It was to balance refcount with netdev_put() in mpls_rt_alloc().
I'll post the patch below.
(Updating rt->rt_nhn is not strictlly needed for netdev_put()
because it has NULL check and rt is allocated with kzalloc(),
but it's a bit error prone, so I'll keep it)
---8<---
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index ca504d9626cf..4a81514e919a 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -922,8 +922,7 @@ static int mpls_nh_build_multi(struct mpls_route_config *cfg,
struct nlattr *nla_via, *nla_newdst;
int remaining = cfg->rc_mp_len;
int err = 0;
-
- rt->rt_nhn = 0;
+ u8 nhs = 0;
change_nexthops(rt) {
int attrlen;
@@ -959,12 +958,15 @@ static int mpls_nh_build_multi(struct mpls_route_config *cfg,
rt->rt_nhn_alive--;
rtnh = rtnh_next(rtnh, &remaining);
- rt->rt_nhn++;
+ nhs++;
} endfor_nexthops(rt);
+ rt->rt_nhn = nhs;
+
return 0;
errout:
+ rt->rt_nhn = nhs;
return err;
}
---8<---
>
> This commit modified function `mpls_nx_build_multi` by setting
> `rt->rt_nhn` to 0 at the
> start of the function. However, the loop `change_nexthops` just below
> depends on
> `rt->rt_nhn` to know the actual number of nexthops that it should build.
> As `rt->rt_nhn`
> is set to 0 just before, **no nexthop is ever built**, leading to a dead
> route. Even if we
> remove this modification, this commit incorrectly increments
> `rt->rt_nhn` at the end of
> the loop (`rt->rt_nhn++`), such that the loop always end with an error
> as it tries to
> constructs more nexthops that actually provided.
>
> Commenting these two lines fix the issue, and allows to create once
> again MPLS routes
> with multiple nexthops:
>
> ```
> modprobe mpls_iptunnel mpls_router
> sysctl net.mpls.platform_labels=100000
> ip link set dummy0 up
> ip addr add fc00:1::1/112 dev dummy0
> ip addr add fc00:2::1/112 dev dummy0
> ip -M route add 16000 \
> nexthop via inet6 fc00:1::2 as 16001 \
> nexthop via inet6 fc00:2::2 as 16002
>
> # Check the route
> ip -M route
> # Output:
> # 16000
> # nexthop as to 16001 via inet6 fc00:1::2 dev dummy0
> # nexthop as to 16002 via inet6 fc00:2::2 dev dummy0
> #
> # Route is accepted and present !
> ```
>
> Overall, I think it would be interesting to discuss what this patch was
> trying to achieve,
> and how we can conciliate both use-cases.
>
> Best regards and looking forward to hearing from you,
> Doeraene Anthony
^ permalink raw reply related
* Re: [PATCH] octeontx2-af: Free BPID bitmap on setup failure
From: Jakub Kicinski @ 2026-06-25 15:50 UTC (permalink / raw)
To: Haoxiang Li
Cc: sgoutham, lcherian, gakula, hkelam, sbhatta, andrew+netdev, davem,
edumazet, pabeni, horms, netdev, linux-kernel, nshettyj, rkannoth
In-Reply-To: <20260623114316.2182271-1-haoxiang_li2024@163.com>
On Tue, 23 Jun 2026 19:43:16 +0800 Haoxiang Li wrote:
> nix_setup_bpids() allocates bp->bpids with rvu_alloc_bitmap(), which uses
> a plain kcalloc(). If any of the following devm_kcalloc() allocations for
> the BPID mapping arrays fails, the function returns without freeing the
> bitmap. Free the BPID bitmap before returning from those error paths.
Marvell, you are actively working on this driver but review none of the
patches posted by others. This is your last warning, please, you have to
start reviewing the fixes.
^ permalink raw reply
* Re: [PATCH net-next] Documentation: networking: Add a test plan for ethtool pause validation
From: Andrew Lunn @ 2026-06-25 15:46 UTC (permalink / raw)
To: Maxime Chevallier
Cc: Jakub Kicinski, davem, Eric Dumazet, Paolo Abeni, Simon Horman,
Russell King, Heiner Kallweit, Jonathan Corbet, Shuah Khan,
Oleksij Rempel, Vladimir Oltean, Florian Fainelli,
thomas.petazzoni, netdev, linux-kernel, linux-doc
In-Reply-To: <7a88fee8-bbb3-480f-9c93-677b7270a940@bootlin.com>
On Thu, Jun 25, 2026 at 12:46:44PM +0200, Maxime Chevallier wrote:
> Hi Andrew,
>
> On 5/29/26 14:59, Andrew Lunn wrote:
>
> (This discussion was a while ago, but this bit of context should be enough)
>
> > But we also need to consider that for some APIs, we have decided that
> > a configuration can be set now, which does not actually apply in our
> > current conditions, but it will be stored away for when conditions
> > change and it is applicable. The half duplex case could fit that. When
> > the link is currently half duplex, you can configure pause, but you
> > don't expect it to actually change the current behaviour. It only
> > kicks in when the link renegotiates to full duplex sometime in the
> > future. We have to also consider this the other way around. The link
> > is full duplex and pause is configured by the user. Something happens
> > with the LP and the link renegotiates to half duplex. The local end
> > should not throw away the configuration, it simply cannot apply it
> > given the current situation.
>
> I'm writing the test description for HD with a better formatting, so the
> HD test wouldn't be about "are we using pause stuff while in HD" as it
> doesn't make sense, but rather "do we correctly store the pause settings
> aside for later".
O.K.
> I'm realising that we don't really have an API to report the *true* in-use pause
> settings. Taking HD as an example :
>
> # ethtool -s eth2 duplex half
>
> [588209.379363] mvpp2 f4000000.ethernet eth2: Link is Up - 100Mbps/Half - flow control off
>
> # ethtool eth2
> [...]
> Supported pause frame use: Symmetric Receive-only
> Advertised pause frame use: Symmetric Receive-only
> Link partner advertised pause frame use: Symmetric Receive-only
Does it even make sense to advertise this when in HD? But i don't
think we need to consider this now. I consider HD low priority, i
doubt it is actually used very often. We should concentrate on FD
testing.
> # ethtool -a eth2
> Autonegotiate: on
> RX: off
> TX: off
> RX negotiated: on
> TX negotiated: on
>
>
> Sure, pause and HD don't make sense, however what I find confusing to some
> extent is that the only place we have information about the *actual* pause
> settings is the "link is Up" log in dmesg.
Maybe we should extend ksetting get to return the resolved pause
parameters? But i'm not sure how much that actually gives us. Anything
using phylink will just ask phylink to fill in the ksettings
information, and it seems unlikely phylink gets it wrong. What we are
really trying to test is drivers which don't user phylink, those are
the ones which are generally broken, and they are not going to
implement anything new in ksettings. So i think the test has to look
at:
> Advertised pause frame use: Symmetric Receive-only
> Link partner advertised pause frame use: Symmetric Receive-only
and check these match what we expect.
Andrew
^ permalink raw reply
* Re: [PATCH net-next] net: neigh: avoid calling neigh_forced_gc on every alloc when table is full
From: Jakub Kicinski @ 2026-06-25 15:42 UTC (permalink / raw)
To: Vimal Agrawal; +Cc: netdev, kuniyu, edumazet, vimal.agrawal
In-Reply-To: <20260625102020.92814-1-vimal.agrawal@sophos.com>
On Thu, 25 Jun 2026 10:20:20 +0000 Vimal Agrawal wrote:
> Once the neighbour table exceeds gc_thresh3, neigh_forced_gc() is called
> on every allocation attempt with no rate limiting. In workloads with mostly
> active/reachable entries, the GC walk traverses a large portion of the
> neighbour table without reclaiming entries, holding tbl->lock for an
> extended period. This causes severe lock contention and allocation
> latencies exceeding 16ms under sustained neighbour creation.
>
> Add a pre-lock check in neigh_forced_gc() to skip the GC run if one was
> performed within the last second, avoiding repeated full table scans and
> lock acquisitions on the hot allocation path.
>
> Profiling of neigh_create() shows ~3 orders of magnitude latency
> improvement with this change.
I'm not an expert on neigh but 1 second seems a little aggressive.
Can you see if 10msec doesn't give us a similar win?
> net/core/neighbour.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index 1349c0eedb64..078842db3c5f 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -260,6 +260,9 @@ static int neigh_forced_gc(struct neigh_table *tbl)
> int shrunk = 0;
> int loop = 0;
>
> + if (!time_after(jiffies, READ_ONCE(tbl->last_flush) + HZ))
> + return 0;
> +
> NEIGH_CACHE_STAT_INC(tbl, forced_gc_runs);
>
> spin_lock_bh(&tbl->lock);
^ permalink raw reply
* Re: [PATCH v2 0/4] vhost/vsock: add support for VHOST_RESET_OWNER and CPR migration
From: Pavel Tikhomirov @ 2026-06-25 15:32 UTC (permalink / raw)
To: Andrey Drobyshev, linux-kernel
Cc: kvm, virtualization, netdev, sgarzare, mst, stefanha,
dongli.zhang, maciej.szmigiero, bchaney, mark.kanda, den
In-Reply-To: <20260622175808.508084-1-andrey.drobyshev@virtuozzo.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
On 6/22/26 19:58, Andrey Drobyshev wrote:
> v1 -> v2:
>
> * Patch 2 (suppress EHOSTUNREACH): replace 'cpr_paused' + backend check
> with a single 'started' latch;
> * Patch 3 (re-scan TX virtqueue): reword commit message;
> * Patch 4 (VHOST_RESET_OWNER):
> - fix a vhost_worker use-after-free / stuck VHOST_WORK_QUEUED stall
> against the lockless send path;
> - drop the no-op vsock_for_each_connected_socket() iteration;
> * Shuffle the patches, keep RESET_OWNER implementation last to preserve
> bisectability;
> * Reword the cover letter.
>
> v1: https://lore.kernel.org/virtualization/20260612165718.433546-1-andrey.drobyshev@virtuozzo.com
>
> Host<-->guest connections via AF_VSOCK sockets aren't supposed to
> outlive VM migration, since VM is moving to another host. However
> there's a special case, which is QEMU live-update, or CPR
> (checkpoint-restore) migration. In this case, VM remains on the same
> host, and we'd like such connections to persist.
>
> For this to work, we need to be able to transfer device ownership from
> source QEMU to dest QEMU. Namely, source needs to reset ownership by
> issuing VHOST_RESET_OWNER ioctl, and then target has to claim it by
> calling VHOST_SET_OWNER.
>
> Since VHOST_RESET_OWNER isn't yet implemented for vhost-vsock, let's add
> such implementation. Patch 1 is a preliminary helper. Patches 2 and 3
> fix the pre-existing issues which do manifest during CPR / RESET_OWNER.
> Patch 4 is the ioctl's implementation itself - we keep it last to
> preserve bisectability.
>
> There's a complementary series for QEMU [0] adding support of vhost-vsock
> devices during CPR migration.
>
> I've tested this (patched QEMU + patched kernel) approximately as follows:
>
> * Run listener in the guest:
> socat -u VSOCK-LISTEN:9999 - >/tmp/recv.bin
>
> * Run data transfer from host to guest:
> socat -u FILE:/root/bigfile.bin VSOCK-CONNECT:CID:9999
>
> * Perform CPR migration during transfer (either cpr-exec or cpr-transfer)
> * Check that file hash sum matches
>
> [0] https://lore.kernel.org/qemu-devel/20260619105514.128812-1-andrey.drobyshev@virtuozzo.com
>
> Andrey Drobyshev (2):
> vhost/vsock: suppress EHOSTUNREACH fast-fail during CPR pause
> vhost/vsock: re-scan TX virtqueue on device start
>
> Pavel Tikhomirov (2):
> vhost/vsock: split out vhost_vsock_drop_backends helper
> vhost/vsock: add VHOST_RESET_OWNER ioctl
>
> drivers/vhost/vsock.c | 96 ++++++++++++++++++++++++++++++++++---------
> 1 file changed, 76 insertions(+), 20 deletions(-)
>
--
Best regards, Pavel Tikhomirov
Senior Software Developer, Virtuozzo.
^ permalink raw reply
* [PATCH] net: usb: cx82310_eth: stop parsing reboot marker as packet
From: Tianchu Chen @ 2026-06-25 15:32 UTC (permalink / raw)
To: andrew+netdev, davem, edumazet, kuba, pabeni; +Cc: linux-usb, netdev
From: Tianchu Chen <flynnnchen@tencent.com>
Discovered by Atuin - Automated Vulnerability Discovery Engine.
cx82310_rx_fixup() treats an RX length of 0xffff as a device reboot
marker and schedules work to re-enable ethernet mode, but then continues
processing the marker as a normal packet length. This is an out-of-bounds
heap write controlled by the usb device.
Return immediately after scheduling the recovery work so the marker skb
is dropped instead of being assembled as packet data.
Fixes: ca139d76b0d9 ("cx82310_eth: re-enable ethernet mode after router reboot")
Cc: stable@vger.kernel.org
Signed-off-by: Tianchu Chen <flynnnchen@tencent.com>
---
drivers/net/usb/cx82310_eth.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/net/usb/cx82310_eth.c b/drivers/net/usb/cx82310_eth.c
index 068acb052..5df657acf 100644
--- a/drivers/net/usb/cx82310_eth.c
+++ b/drivers/net/usb/cx82310_eth.c
@@ -282,6 +282,7 @@ static int cx82310_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
if (len == 0xffff) {
netdev_info(dev->net, "router was rebooted, re-enabling ethernet mode");
schedule_work(&priv->reenable_work);
+ return 0;
} else if (len > CX82310_MTU) {
netdev_err(dev->net, "RX packet too long: %d B\n", len);
return 0;
--
2.51.0
^ permalink raw reply related
* RE: [PATCH net v5 1/4] net: ethernet: oa_tc6: Interrupt is active low, level triggered.
From: Selvamani Rajagopal @ 2026-06-25 15:31 UTC (permalink / raw)
To: Parthiban.Veerasooran@microchip.com, andrew+netdev@lunn.ch,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, robh@kernel.org, krzk+dt@kernel.org,
conor+dt@kernel.org, Piergiorgio Beruto
Cc: andrew@lunn.ch, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, Conor.Dooley@microchip.com,
devicetree@vger.kernel.org
In-Reply-To: <CYYPR02MB982836BC273D09FD3BDE623583EC2@CYYPR02MB9828.namprd02.prod.outlook.com>
Parthiban,
Let me know if you prefer updating the patchset. I certainly prefer adding a NULL check
In oa_tc6_update_rx_skb function.
>
> Root cause seems to be same. When oa_tc6_update_rx_skb function is called, tc6-
> >rx_skb
> seems to be NULL, which may mean, controller seems to be not getting start
>
> I have a theory. Look at line #933. We have the following comment. I am sure this could
> be true
> for the call to oa_tc6_prcs_rx_frame_end at line #926 or oa_tc6_prcs_ongoing_rx_frame
> at line #950.
> /* After rx buffer overflow error received, there might be a
> * possibility of getting an end valid of a previously
> * incomplete rx frame along with the new rx frame start valid.
> */
>
^ permalink raw reply
* Re: [PATCH net-next] selftests/xsk: preserve UMEM view in bidi test
From: Jakub Kicinski @ 2026-06-25 15:29 UTC (permalink / raw)
To: Maciej Fijalkowski
Cc: netdev, bpf, magnus.karlsson, stfomichev, pabeni, horms,
tushar.vyavahare, kerneljasonxing
In-Reply-To: <aj1He9vNkRh+Ettf@boxer>
On Thu, 25 Jun 2026 17:21:31 +0200 Maciej Fijalkowski wrote:
> On Thu, Jun 25, 2026 at 07:36:36AM -0700, Jakub Kicinski wrote:
> > On Thu, 25 Jun 2026 12:35:12 +0200 Maciej Fijalkowski wrote:
> > > On Wed, Jun 24, 2026 at 07:33:26PM -0700, Jakub Kicinski wrote:
> > > I have not checked if this has been -net propagated already, but the rule
> > > of thumb on bpf side was that all selftests related effort goes to -next.
> > > Is it different on netdev side?
> >
> > We prefer -next too, but during the merge window net-next is closed.
> >
> > What we definitely don't want is a -next patch with a Fixes tag.
> > So either net or drop the tag, please.
>
> I have verified that offending commit is present in net tree. Could you
> apply the v2 that I unfortunately sent already targeted at net-next, to
> net tree?
Will do. Hopefully it applies, cause net-next wasn't forwarded yet
so it doesn't include Tushar's patches.
^ permalink raw reply
* Re: [PATCH net-next] Documentation: networking: Add a test plan for ethtool pause validation
From: Maxime Chevallier @ 2026-06-25 15:29 UTC (permalink / raw)
To: Andrew Lunn, Jakub Kicinski
Cc: davem, Eric Dumazet, Paolo Abeni, Simon Horman, Russell King,
Heiner Kallweit, Jonathan Corbet, Shuah Khan, Oleksij Rempel,
Vladimir Oltean, Florian Fainelli, thomas.petazzoni, netdev,
linux-kernel, linux-doc
In-Reply-To: <5cb8e2b4-8eb6-4446-9b90-1cd4c7964cd9@lunn.ch>
Hi Andrew,
On 5/27/26 04:47, Andrew Lunn wrote:
> On Tue, May 26, 2026 at 05:24:47PM -0700, Jakub Kicinski wrote:
>> On Fri, 22 May 2026 19:51:06 +0200 Maxime Chevallier (Netdev
>> Foundation) wrote:
>>> Documentation/networking/pause_test_plan.rst | 556 +++++++++++++++++++
>>
>> It'd be great to hear from others but IMHO in the current form this is
>> not suitable for Documentation/networking/ We can commit the "knowledge"
>> part but enumerating the test cases seems odd for Documentation/.
>
> Sorry, not looked too deeply at the actual content yet.
>
> What i was thinking was a python file, which sphinx can ingest to
> produce documentation, and place holders were code would be added to
> implement the actual test during the next phase.
>
> This is how i've done testing in the past. I would be the evil one who
> thought up the tests and described them in detail using sphinx markup
> in a python test template file. After some review they got passed off
> to a python developer for implementation. And when they got run and
> failed, sometimes the feature developer, the test developer and myself
> got together to figure who made the error.
>
> I'm not sure we even need sphinx. What i find important is that the
> test is documented. What kAPI calls should be made with what
> parameters. What results we are expected and why? So that when a test
> fails, a developer has the information they need to fix their
> code. The Why? is important, and often missing from the kernel tests.
This isn't sphynx, but I've come-up with something like this for a
test definition :
@ksft_ethtool_needs_supported_anyof([Pause, Asym_Pause])
def test_ethtool_pause_advertising(cfg, peer) -> None:
"""Pause advertisement
Validate that changing pause params through the ETHTOOL_MSG_PAUSE command
translates to a change in the advertised pause params, and that these
parameters are correct w.r.t the supported pause params and requested pause
params.
This exercises the .set_pauseparams() ethtool ops for MAC configuration,
as well as the reconfiguration of the PHY's advertising and negociation.
On non-phylink MACs, the MAC should call phy_set_sym_pause() to update the
PHY's advertising, and restart a negotiation with phy_start_aneg() if
need be. Failure to do so will result on the wrong advertising parameters.
Pn phylink-enabled MACs, phylink deals with the PHY reconfiguration provided
the MAC driver calls phylink_ethtool_set_pauseparam().
Failing this test likely means that the PHY driver is not correctly advertising
pause settings, either due to the MAC not triggering a PHY reconfiguration,
a misconficonfiguration of the advertising registers by the PHY, or by
mis-handling the phydev->advertising bitfield in the PHY driver directly.
The validation is made by looking at the advertised modes locally, as well as
what the peer's 'lp_advertising' values report.
cfg -- local device's interface configuration
peer -- peer device handle
"""
# Initial conditions :
# - Local interface is admin UP, and reports lowlayer link UP
# - Remote interface is adming UP, and reports lowlayer link UP
#
# Test 1
# - SKIP if supported doesn't contain "Pause"
# - run 'ethtool -A ethX rx on tx on autoneg on'
# - FAIL if the return isn't 0
# - FAIL if ETHTOOL_A_LINKMODES_OURS's advertised values does not contain
# "Pause" or contains "Asym_Pause"
# - FAIL if peer's lp_advertising doesn't contain "Pause" or contains
# "Asym_Pause"
# - Succeed otherwise
#
# Test 2
# - SKIP uif supported doesn't contain both "Pause" and "Asym_Pause"
# - run 'ethtool -A ethX rx on tx on autoneg on'
# - FAIL if the return isn't 0
# - FAIL if ETHTOOL_A_LINKMODES_OURS's advertised values does not contain
# "Pause" or contains "Asym_Pause"
# - FAIL if peer's lp_advertising doesn't contain "Pause" or contains
# "Asym_Pause"
#
# ...
The annotation defines the pre-requisites in terms of locally supported
linkmodes, we have a docstring containing information for developpers
to debug their drivers, what I'm unsure about is the commented-out part
below, so either one big function testing multiple adjacent scenarios
or indivitual functions.
We could also use annotations to enumerate the various combinations of
modes to test.
That's just an extract of the full test suite for Pause, but before
writing the whole thing down i figure it's better to iterate on a single
test's design.
What do you think ?
Maxime
^ permalink raw reply
* Re: [PATCH net v4 2/2] net: phy: mdio-i2c: defer RollBall bridge probe to PHY discovery
From: Jakub Kicinski @ 2026-06-25 15:23 UTC (permalink / raw)
To: Aleksander Jan Bajkowski
Cc: Petr Wozniak, Russell King, Andrew Lunn, Heiner Kallweit,
David S . Miller, Eric Dumazet, Paolo Abeni, netdev, linux-kernel,
linux-phy, Maxime Chevallier, Bjorn Mork, Marek Behun
In-Reply-To: <9f813a8e-8b9a-4708-b3b6-db4972adac35@wp.pl>
On Wed, 24 Jun 2026 23:44:19 +0200 Aleksander Jan Bajkowski wrote:
> > For genuine RollBall modules (e.g. FLYPRO SFP-10GT-CS-30M with Aquantia
> > AQR113C) the probe now runs after initialization is complete and
> > correctly returns 0, so PHY detection proceeds normally.
> The FLPRO SFP module still fails to detect the PHY. It is necessary to
> increase `module_t_wait` to 20 seconds. Most likely, during this time
> the module loads the PHY firmware from SPI memory or from the
> microcontroller (rollball bridge) via MDIO. Same probably applies to
> most SFP modules with a PHY that load firmware at start-up (AQR113,
> RTL8261C etc.).
Just to clarify is FLPRO a typo or a knock off ?
Do you want something to be changed here or you're just flagging that
more follow ups are needed if we want to cover more modules?
^ permalink raw reply
* RE: [PATCH net v5 1/4] net: ethernet: oa_tc6: Interrupt is active low, level triggered.
From: Selvamani Rajagopal @ 2026-06-25 15:21 UTC (permalink / raw)
To: Parthiban.Veerasooran@microchip.com, andrew+netdev@lunn.ch,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, robh@kernel.org, krzk+dt@kernel.org,
conor+dt@kernel.org, Piergiorgio Beruto
Cc: andrew@lunn.ch, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, Conor.Dooley@microchip.com,
devicetree@vger.kernel.org
In-Reply-To: <f127837f-e08f-48e0-a3a9-906e1d61d6bb@microchip.com>
> -----Original Message-----
> From: Parthiban.Veerasooran@microchip.com <Parthiban.Veerasooran@microchip.com>
> Subject: Re: [PATCH net v5 1/4] net: ethernet: oa_tc6: Interrupt is active low, level triggered.
>
>
> With your above patches, I did a quick test (Test case 2) with two
> Microchip MAC-PHYs and faced a similar issue reported before. Sharing
> the dmesg crash log for your reference.
Root cause seems to be same. When oa_tc6_update_rx_skb function is called, tc6->rx_skb
seems to be NULL, which may mean, controller seems to be not getting start
I have a theory. Look at line #933. We have the following comment. I am sure this could be true
for the call to oa_tc6_prcs_rx_frame_end at line #926 or oa_tc6_prcs_ongoing_rx_frame at line #950.
/* After rx buffer overflow error received, there might be a
* possibility of getting an end valid of a previously
* incomplete rx frame along with the new rx frame start valid.
*/
Either we change the following line in the function oa_tc6_update_rx_skb
if ((tc6->rx_skb->tail + length) > tc6->rx_skb->end) {
to
if (tc6->rx_skb == NULL || (tc6->rx_skb->tail + length) > tc6->rx_skb->end) {
Or add a check
If (tc6->rx_skb) before calling above mentioned two functions from the callee function.
I could do. But I have no way of verifying this. I am sure it will fix the crash. I would like to confirm
whether traffic recovers.
>
> [ 2863.182105] eth1: Receive buffer overflow error
> [ 2863.199905] eth1: Receive buffer overflow error
> [ 2867.669312] Unable to handle kernel NULL pointer dereference at
> virtual address 00000000000000b8
^ permalink raw reply
* Re: [PATCH net-next] selftests/xsk: preserve UMEM view in bidi test
From: Maciej Fijalkowski @ 2026-06-25 15:21 UTC (permalink / raw)
To: Jakub Kicinski
Cc: netdev, bpf, magnus.karlsson, stfomichev, pabeni, horms,
tushar.vyavahare, kerneljasonxing
In-Reply-To: <20260625073636.449a28c0@kernel.org>
On Thu, Jun 25, 2026 at 07:36:36AM -0700, Jakub Kicinski wrote:
> On Thu, 25 Jun 2026 12:35:12 +0200 Maciej Fijalkowski wrote:
> > On Wed, Jun 24, 2026 at 07:33:26PM -0700, Jakub Kicinski wrote:
> > > On Tue, 23 Jun 2026 11:10:08 +0200 Maciej Fijalkowski wrote:
> > > > Subject: [PATCH net-next] selftests/xsk: preserve UMEM view in bidi test
> > >
> > > Do you want it in net? Either way - we'll need a rebase
> >
> > I have not checked if this has been -net propagated already, but the rule
> > of thumb on bpf side was that all selftests related effort goes to -next.
> > Is it different on netdev side?
>
> We prefer -next too, but during the merge window net-next is closed.
>
> What we definitely don't want is a -next patch with a Fixes tag.
> So either net or drop the tag, please.
I have verified that offending commit is present in net tree. Could you
apply the v2 that I unfortunately sent already targeted at net-next, to
net tree?
^ permalink raw reply
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