* [PATCH stable 5.10 v2 1/2] net: openvswitch: fix race on port output
2025-03-25 19:22 [PATCH stable 5.10 v2 0/2] openvswitch port output fixes Florian Fainelli
@ 2025-03-25 19:22 ` Florian Fainelli
2025-03-26 2:23 ` Sasha Levin
2025-03-25 19:22 ` [PATCH stable 5.10 v2 2/2] openvswitch: fix lockup on tx to unregistering netdev with carrier Florian Fainelli
1 sibling, 1 reply; 5+ messages in thread
From: Florian Fainelli @ 2025-03-25 19:22 UTC (permalink / raw)
To: stable
Cc: Felix Huettner, Luca Czesla, Eric Dumazet, Simon Horman,
Jakub Kicinski, Carlos Soto, Florian Fainelli, David S. Miller,
Pravin B Shelar, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, Sasha Levin, Willem de Bruijn,
Paolo Abeni, Breno Leitao, Yan Zhai, Benoît Monin,
Thomas Graf, Justin Pettit, Andy Zhou,
open list:NETWORKING [GENERAL], open list, open list:OPENVSWITCH,
open list:BPF (Safe dynamic programs and tools)
From: Felix Huettner <felix.huettner@mail.schwarz>
[ Upstream commit 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 ]
assume the following setup on a single machine:
1. An openvswitch instance with one bridge and default flows
2. two network namespaces "server" and "client"
3. two ovs interfaces "server" and "client" on the bridge
4. for each ovs interface a veth pair with a matching name and 32 rx and
tx queues
5. move the ends of the veth pairs to the respective network namespaces
6. assign ip addresses to each of the veth ends in the namespaces (needs
to be the same subnet)
7. start some http server on the server network namespace
8. test if a client in the client namespace can reach the http server
when following the actions below the host has a chance of getting a cpu
stuck in a infinite loop:
1. send a large amount of parallel requests to the http server (around
3000 curls should work)
2. in parallel delete the network namespace (do not delete interfaces or
stop the server, just kill the namespace)
there is a low chance that this will cause the below kernel cpu stuck
message. If this does not happen just retry.
Below there is also the output of bpftrace for the functions mentioned
in the output.
The series of events happening here is:
1. the network namespace is deleted calling
`unregister_netdevice_many_notify` somewhere in the process
2. this sets first `NETREG_UNREGISTERING` on both ends of the veth and
then runs `synchronize_net`
3. it then calls `call_netdevice_notifiers` with `NETDEV_UNREGISTER`
4. this is then handled by `dp_device_event` which calls
`ovs_netdev_detach_dev` (if a vport is found, which is the case for
the veth interface attached to ovs)
5. this removes the rx_handlers of the device but does not prevent
packages to be sent to the device
6. `dp_device_event` then queues the vport deletion to work in
background as a ovs_lock is needed that we do not hold in the
unregistration path
7. `unregister_netdevice_many_notify` continues to call
`netdev_unregister_kobject` which sets `real_num_tx_queues` to 0
8. port deletion continues (but details are not relevant for this issue)
9. at some future point the background task deletes the vport
If after 7. but before 9. a packet is send to the ovs vport (which is
not deleted at this point in time) which forwards it to the
`dev_queue_xmit` flow even though the device is unregistering.
In `skb_tx_hash` (which is called in the `dev_queue_xmit`) path there is
a while loop (if the packet has a rx_queue recorded) that is infinite if
`dev->real_num_tx_queues` is zero.
To prevent this from happening we update `do_output` to handle devices
without carrier the same as if the device is not found (which would
be the code path after 9. is done).
Additionally we now produce a warning in `skb_tx_hash` if we will hit
the infinite loop.
bpftrace (first word is function name):
__dev_queue_xmit server: real_num_tx_queues: 1, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 1
netdev_core_pick_tx server: addr: 0xffff9f0a46d4a000 real_num_tx_queues: 1, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 1
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 2, reg_state: 1
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 6, reg_state: 2
ovs_netdev_detach_dev server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, reg_state: 2
netdev_rx_handler_unregister server: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024, reg_state: 2
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
netdev_rx_handler_unregister ret server: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024, reg_state: 2
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 27, reg_state: 2
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 22, reg_state: 2
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 18, reg_state: 2
netdev_unregister_kobject: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
ovs_vport_send server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
__dev_queue_xmit server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
netdev_core_pick_tx server: addr: 0xffff9f0a46d4a000 real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
broken device server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024
ovs_dp_detach_port server: real_num_tx_queues: 0 cpu 9, pid: 9124, tid: 9124, reg_state: 2
synchronize_rcu_expedited: cpu 9, pid: 33604, tid: 33604
stuck message:
watchdog: BUG: soft lockup - CPU#5 stuck for 26s! [curl:1929279]
Modules linked in: veth pktgen bridge stp llc ip_set_hash_net nft_counter xt_set nft_compat nf_tables ip_set_hash_ip ip_set nfnetlink_cttimeout nfnetlink openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 tls binfmt_misc nls_iso8859_1 input_leds joydev serio_raw dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua sch_fq_codel drm efi_pstore virtio_rng ip_tables x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel virtio_net ahci net_failover crypto_simd cryptd psmouse libahci virtio_blk failover
CPU: 5 PID: 1929279 Comm: curl Not tainted 5.15.0-67-generic #74-Ubuntu
Hardware name: OpenStack Foundation OpenStack Nova, BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:netdev_pick_tx+0xf1/0x320
Code: 00 00 8d 48 ff 0f b7 c1 66 39 ca 0f 86 e9 01 00 00 45 0f b7 ff 41 39 c7 0f 87 5b 01 00 00 44 29 f8 41 39 c7 0f 87 4f 01 00 00 <eb> f2 0f 1f 44 00 00 49 8b 94 24 28 04 00 00 48 85 d2 0f 84 53 01
RSP: 0018:ffffb78b40298820 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff9c8773adc2e0 RCX: 000000000000083f
RDX: 0000000000000000 RSI: ffff9c8773adc2e0 RDI: ffff9c870a25e000
RBP: ffffb78b40298858 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff9c870a25e000
R13: ffff9c870a25e000 R14: ffff9c87fe043480 R15: 0000000000000000
FS: 00007f7b80008f00(0000) GS:ffff9c8e5f740000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7b80f6a0b0 CR3: 0000000329d66000 CR4: 0000000000350ee0
Call Trace:
<IRQ>
netdev_core_pick_tx+0xa4/0xb0
__dev_queue_xmit+0xf8/0x510
? __bpf_prog_exit+0x1e/0x30
dev_queue_xmit+0x10/0x20
ovs_vport_send+0xad/0x170 [openvswitch]
do_output+0x59/0x180 [openvswitch]
do_execute_actions+0xa80/0xaa0 [openvswitch]
? kfree+0x1/0x250
? kfree+0x1/0x250
? kprobe_perf_func+0x4f/0x2b0
? flow_lookup.constprop.0+0x5c/0x110 [openvswitch]
ovs_execute_actions+0x4c/0x120 [openvswitch]
ovs_dp_process_packet+0xa1/0x200 [openvswitch]
? ovs_ct_update_key.isra.0+0xa8/0x120 [openvswitch]
? ovs_ct_fill_key+0x1d/0x30 [openvswitch]
? ovs_flow_key_extract+0x2db/0x350 [openvswitch]
ovs_vport_receive+0x77/0xd0 [openvswitch]
? __htab_map_lookup_elem+0x4e/0x60
? bpf_prog_680e8aff8547aec1_kfree+0x3b/0x714
? trace_call_bpf+0xc8/0x150
? kfree+0x1/0x250
? kfree+0x1/0x250
? kprobe_perf_func+0x4f/0x2b0
? kprobe_perf_func+0x4f/0x2b0
? __mod_memcg_lruvec_state+0x63/0xe0
netdev_port_receive+0xc4/0x180 [openvswitch]
? netdev_port_receive+0x180/0x180 [openvswitch]
netdev_frame_hook+0x1f/0x40 [openvswitch]
__netif_receive_skb_core.constprop.0+0x23d/0xf00
__netif_receive_skb_one_core+0x3f/0xa0
__netif_receive_skb+0x15/0x60
process_backlog+0x9e/0x170
__napi_poll+0x33/0x180
net_rx_action+0x126/0x280
? ttwu_do_activate+0x72/0xf0
__do_softirq+0xd9/0x2e7
? rcu_report_exp_cpu_mult+0x1b0/0x1b0
do_softirq+0x7d/0xb0
</IRQ>
<TASK>
__local_bh_enable_ip+0x54/0x60
ip_finish_output2+0x191/0x460
__ip_finish_output+0xb7/0x180
ip_finish_output+0x2e/0xc0
ip_output+0x78/0x100
? __ip_finish_output+0x180/0x180
ip_local_out+0x5e/0x70
__ip_queue_xmit+0x184/0x440
? tcp_syn_options+0x1f9/0x300
ip_queue_xmit+0x15/0x20
__tcp_transmit_skb+0x910/0x9c0
? __mod_memcg_state+0x44/0xa0
tcp_connect+0x437/0x4e0
? ktime_get_with_offset+0x60/0xf0
tcp_v4_connect+0x436/0x530
__inet_stream_connect+0xd4/0x3a0
? kprobe_perf_func+0x4f/0x2b0
? aa_sk_perm+0x43/0x1c0
inet_stream_connect+0x3b/0x60
__sys_connect_file+0x63/0x70
__sys_connect+0xa6/0xd0
? setfl+0x108/0x170
? do_fcntl+0xe8/0x5a0
__x64_sys_connect+0x18/0x20
do_syscall_64+0x5c/0xc0
? __x64_sys_fcntl+0xa9/0xd0
? exit_to_user_mode_prepare+0x37/0xb0
? syscall_exit_to_user_mode+0x27/0x50
? do_syscall_64+0x69/0xc0
? __sys_setsockopt+0xea/0x1e0
? exit_to_user_mode_prepare+0x37/0xb0
? syscall_exit_to_user_mode+0x27/0x50
? __x64_sys_setsockopt+0x1f/0x30
? do_syscall_64+0x69/0xc0
? irqentry_exit+0x1d/0x30
? exc_page_fault+0x89/0x170
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f7b8101c6a7
Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 18 89 54 24 0c 48 89 34 24 89
RSP: 002b:00007ffffd6b2198 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7b8101c6a7
RDX: 0000000000000010 RSI: 00007ffffd6b2360 RDI: 0000000000000005
RBP: 0000561f1370d560 R08: 00002795ad21d1ac R09: 0030312e302e302e
R10: 00007ffffd73f080 R11: 0000000000000246 R12: 0000561f1370c410
R13: 0000000000000000 R14: 0000000000000005 R15: 0000000000000000
</TASK>
Fixes: 7f8a436eaa2c ("openvswitch: Add conntrack action")
Co-developed-by: Luca Czesla <luca.czesla@mail.schwarz>
Signed-off-by: Luca Czesla <luca.czesla@mail.schwarz>
Signed-off-by: Felix Huettner <felix.huettner@mail.schwarz>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/ZC0pBXBAgh7c76CA@kernel-bug-kernel-bug
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Carlos Soto <carlos.soto@broadcom.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
net/core/dev.c | 1 +
net/openvswitch/actions.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 81f9fd0c5830..2f7bd1fe5851 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3231,6 +3231,7 @@ static u16 skb_tx_hash(const struct net_device *dev,
}
if (skb_rx_queue_recorded(skb)) {
+ BUILD_BUG_ON_INVALID(qcount == 0);
hash = skb_get_rx_queue(skb);
if (hash >= qoffset)
hash -= qoffset;
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 85af0e9e0ac6..9b07e2172c94 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -913,7 +913,7 @@ static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
{
struct vport *vport = ovs_vport_rcu(dp, out_port);
- if (likely(vport)) {
+ if (likely(vport && netif_carrier_ok(vport->dev))) {
u16 mru = OVS_CB(skb)->mru;
u32 cutlen = OVS_CB(skb)->cutlen;
--
2.34.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH stable 5.10 v2 2/2] openvswitch: fix lockup on tx to unregistering netdev with carrier
2025-03-25 19:22 [PATCH stable 5.10 v2 0/2] openvswitch port output fixes Florian Fainelli
2025-03-25 19:22 ` [PATCH stable 5.10 v2 1/2] net: openvswitch: fix race on port output Florian Fainelli
@ 2025-03-25 19:22 ` Florian Fainelli
2025-03-26 2:23 ` Sasha Levin
1 sibling, 1 reply; 5+ messages in thread
From: Florian Fainelli @ 2025-03-25 19:22 UTC (permalink / raw)
To: stable
Cc: Ilya Maximets, Friedrich Weber, Aaron Conole, Jakub Kicinski,
Sasha Levin, Carlos Soto, Florian Fainelli, David S. Miller,
Pravin B Shelar, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, Eric Dumazet, Willem de Bruijn,
Paolo Abeni, Breno Leitao, Felix Huettner, Yan Zhai,
Benoît Monin, Thomas Graf, Justin Pettit, Andy Zhou,
Simon Horman, Luca Czesla, open list:NETWORKING [GENERAL],
open list, open list:OPENVSWITCH,
open list:BPF (Safe dynamic programs and tools)
From: Ilya Maximets <i.maximets@ovn.org>
[ Upstream commit 82f433e8dd0629e16681edf6039d094b5518d8ed ]
Commit in a fixes tag attempted to fix the issue in the following
sequence of calls:
do_output
-> ovs_vport_send
-> dev_queue_xmit
-> __dev_queue_xmit
-> netdev_core_pick_tx
-> skb_tx_hash
When device is unregistering, the 'dev->real_num_tx_queues' goes to
zero and the 'while (unlikely(hash >= qcount))' loop inside the
'skb_tx_hash' becomes infinite, locking up the core forever.
But unfortunately, checking just the carrier status is not enough to
fix the issue, because some devices may still be in unregistering
state while reporting carrier status OK.
One example of such device is a net/dummy. It sets carrier ON
on start, but it doesn't implement .ndo_stop to set the carrier off.
And it makes sense, because dummy doesn't really have a carrier.
Therefore, while this device is unregistering, it's still easy to hit
the infinite loop in the skb_tx_hash() from the OVS datapath. There
might be other drivers that do the same, but dummy by itself is
important for the OVS ecosystem, because it is frequently used as a
packet sink for tcpdump while debugging OVS deployments. And when the
issue is hit, the only way to recover is to reboot.
Fix that by also checking if the device is running. The running
state is handled by the net core during unregistering, so it covers
unregistering case better, and we don't really need to send packets
to devices that are not running anyway.
While only checking the running state might be enough, the carrier
check is preserved. The running and the carrier states seem disjoined
throughout the code and different drivers. And other core functions
like __dev_direct_xmit() check both before attempting to transmit
a packet. So, it seems safer to check both flags in OVS as well.
Fixes: 066b86787fa3 ("net: openvswitch: fix race on port output")
Reported-by: Friedrich Weber <f.weber@proxmox.com>
Closes: https://mail.openvswitch.org/pipermail/ovs-discuss/2025-January/053423.html
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Tested-by: Friedrich Weber <f.weber@proxmox.com>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20250109122225.4034688-1-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Carlos Soto <carlos.soto@broadcom.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
net/openvswitch/actions.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 9b07e2172c94..1f05fa85d295 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -913,7 +913,9 @@ static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
{
struct vport *vport = ovs_vport_rcu(dp, out_port);
- if (likely(vport && netif_carrier_ok(vport->dev))) {
+ if (likely(vport &&
+ netif_running(vport->dev) &&
+ netif_carrier_ok(vport->dev))) {
u16 mru = OVS_CB(skb)->mru;
u32 cutlen = OVS_CB(skb)->cutlen;
--
2.34.1
^ permalink raw reply related [flat|nested] 5+ messages in thread