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Message-Id: <1754511711-11188-1-git-send-email-haiyangz@linux.microsoft.com>
Date: Wed, 6 Aug 2025 13:21:51 -0700
From: Haiyang Zhang <haiyangz@...ux.microsoft.com>
To: linux-hyperv@...r.kernel.org,
netdev@...r.kernel.org
Cc: haiyangz@...rosoft.com,
kys@...rosoft.com,
wei.liu@...nel.org,
decui@...rosoft.com,
andrew+netdev@...n.ch,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com,
horms@...nel.org,
davem@...emloft.net,
linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Subject: [PATCH net,v2] hv_netvsc: Fix panic during namespace deletion with VF
From: Haiyang Zhang <haiyangz@...rosoft.com>
The existing code move the VF NIC to new namespace when NETDEV_REGISTER is
received on netvsc NIC. During deletion of the namespace,
default_device_exit_batch() >> default_device_exit_net() is called. When
netvsc NIC is moved back and registered to the default namespace, it
automatically brings VF NIC back to the default namespace. This will cause
the default_device_exit_net() >> for_each_netdev_safe loop unable to detect
the list end, and hit NULL ptr:
[ 231.449420] mana 7870:00:00.0 enP30832s1: Moved VF to namespace with: eth0
[ 231.449656] BUG: kernel NULL pointer dereference, address: 0000000000000010
[ 231.450246] #PF: supervisor read access in kernel mode
[ 231.450579] #PF: error_code(0x0000) - not-present page
[ 231.450916] PGD 17b8a8067 P4D 0
[ 231.451163] Oops: Oops: 0000 [#1] SMP NOPTI
[ 231.451450] CPU: 82 UID: 0 PID: 1394 Comm: kworker/u768:1 Not tainted 6.16.0-rc4+ #3 VOLUNTARY
[ 231.452042] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 11/21/2024
[ 231.452692] Workqueue: netns cleanup_net
[ 231.452947] RIP: 0010:default_device_exit_batch+0x16c/0x3f0
[ 231.453326] Code: c0 0c f5 b3 e8 d5 db fe ff 48 85 c0 74 15 48 c7 c2 f8 fd ca b2 be 10 00 00 00 48 8d 7d c0 e8 7b 77 25 00 49 8b 86 28 01 00 00 <48> 8b 50 10 4c 8b 2a 4c 8d 62 f0 49 83 ed 10 4c 39 e0 0f 84 d6 00
[ 231.454294] RSP: 0018:ff75fc7c9bf9fd00 EFLAGS: 00010246
[ 231.454610] RAX: 0000000000000000 RBX: 0000000000000002 RCX: 61c8864680b583eb
[ 231.455094] RDX: ff1fa9f71462d800 RSI: ff75fc7c9bf9fd38 RDI: 0000000030766564
[ 231.455686] RBP: ff75fc7c9bf9fd78 R08: 0000000000000000 R09: 0000000000000000
[ 231.456126] R10: 0000000000000001 R11: 0000000000000004 R12: ff1fa9f70088e340
[ 231.456621] R13: ff1fa9f70088e340 R14: ffffffffb3f50c20 R15: ff1fa9f7103e6340
[ 231.457161] FS: 0000000000000000(0000) GS:ff1faa6783a08000(0000) knlGS:0000000000000000
[ 231.457707] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 231.458031] CR2: 0000000000000010 CR3: 0000000179ab2006 CR4: 0000000000b73ef0
[ 231.458434] Call Trace:
[ 231.458600] <TASK>
[ 231.458777] ops_undo_list+0x100/0x220
[ 231.459015] cleanup_net+0x1b8/0x300
[ 231.459285] process_one_work+0x184/0x340
To fix it, move the ns change to a workqueue, and take rtnl_lock to avoid
changing the netdev list when default_device_exit_net() is using it.
Cc: stable@...r.kernel.org
Fixes: 4c262801ea60 ("hv_netvsc: Fix VF namespace also in synthetic NIC NETDEV_REGISTER event")
Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
---
v2:
Moved the ns change to a workqueue as suggested by Jakub Kicinski.
---
drivers/net/hyperv/hyperv_net.h | 3 +++
drivers/net/hyperv/netvsc_drv.c | 29 ++++++++++++++++++++++++++++-
2 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index cb6f5482d203..7397c693f984 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -1061,6 +1061,7 @@ struct net_device_context {
struct net_device __rcu *vf_netdev;
struct netvsc_vf_pcpu_stats __percpu *vf_stats;
struct delayed_work vf_takeover;
+ struct delayed_work vfns_work;
/* 1: allocated, serial number is valid. 0: not allocated */
u32 vf_alloc;
@@ -1075,6 +1076,8 @@ struct net_device_context {
struct netvsc_device_info *saved_netvsc_dev_info;
};
+void netvsc_vfns_work(struct work_struct *w);
+
/* Azure hosts don't support non-TCP port numbers in hashing for fragmented
* packets. We can use ethtool to change UDP hash level when necessary.
*/
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index f44753756358..39c892e46cb0 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2522,6 +2522,7 @@ static int netvsc_probe(struct hv_device *dev,
spin_lock_init(&net_device_ctx->lock);
INIT_LIST_HEAD(&net_device_ctx->reconfig_events);
INIT_DELAYED_WORK(&net_device_ctx->vf_takeover, netvsc_vf_setup);
+ INIT_DELAYED_WORK(&net_device_ctx->vfns_work, netvsc_vfns_work);
net_device_ctx->vf_stats
= netdev_alloc_pcpu_stats(struct netvsc_vf_pcpu_stats);
@@ -2666,6 +2667,8 @@ static void netvsc_remove(struct hv_device *dev)
cancel_delayed_work_sync(&ndev_ctx->dwork);
rtnl_lock();
+ cancel_delayed_work_sync(&ndev_ctx->vfns_work);
+
nvdev = rtnl_dereference(ndev_ctx->nvdev);
if (nvdev) {
cancel_work_sync(&nvdev->subchan_work);
@@ -2707,6 +2710,7 @@ static int netvsc_suspend(struct hv_device *dev)
cancel_delayed_work_sync(&ndev_ctx->dwork);
rtnl_lock();
+ cancel_delayed_work_sync(&ndev_ctx->vfns_work);
nvdev = rtnl_dereference(ndev_ctx->nvdev);
if (nvdev == NULL) {
@@ -2800,6 +2804,27 @@ static void netvsc_event_set_vf_ns(struct net_device *ndev)
}
}
+void netvsc_vfns_work(struct work_struct *w)
+{
+ struct net_device_context *ndev_ctx =
+ container_of(w, struct net_device_context, vfns_work.work);
+ struct net_device *ndev;
+
+ if (!rtnl_trylock()) {
+ schedule_delayed_work(&ndev_ctx->vfns_work, 1);
+ return;
+ }
+
+ ndev = hv_get_drvdata(ndev_ctx->device_ctx);
+ if (!ndev)
+ goto out;
+
+ netvsc_event_set_vf_ns(ndev);
+
+out:
+ rtnl_unlock();
+}
+
/*
* On Hyper-V, every VF interface is matched with a corresponding
* synthetic interface. The synthetic interface is presented first
@@ -2810,10 +2835,12 @@ static int netvsc_netdev_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);
+ struct net_device_context *ndev_ctx;
int ret = 0;
if (event_dev->netdev_ops == &device_ops && event == NETDEV_REGISTER) {
- netvsc_event_set_vf_ns(event_dev);
+ ndev_ctx = netdev_priv(event_dev);
+ schedule_delayed_work(&ndev_ctx->vfns_work, 0);
return NOTIFY_DONE;
}
--
2.34.1
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