When virtnet_close is followed by virtnet_open, there is a slight chance
that some TX completions remain unconsumed. Those are handled during the
first NAPI poll, but since dql_reset occurs just beforehand, it can lead
to a crash [1].
This issue can be reproduced by running: `while :; do ip l set DEV down;
ip l set DEV up; done` under heavy network TX load from inside of the
machine.
To fix this, drain unconsumed TX completions if any before dql_reset,
allowing BQL to start cleanly.
------------[ cut here ]------------
kernel BUG at lib/dynamic_queue_limits.c:99!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
CPU: 7 UID: 0 PID: 1598 Comm: ip Tainted: G N 6.12.0net-next_main+ #2
Tainted: [N]=TEST
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), \
BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
RIP: 0010:dql_completed+0x26b/0x290
Code: b7 c2 49 89 e9 44 89 da 89 c6 4c 89 d7 e8 ed 17 47 00 58 65 ff 0d
4d 27 90 7e 0f 85 fd fe ff ff e8 ea 53 8d ff e9 f3 fe ff ff <0f> 0b 01
d2 44 89 d1 29 d1 ba 00 00 00 00 0f 48 ca e9 28 ff ff ff
RSP: 0018:ffffc900002b0d08 EFLAGS: 00010297
RAX: 0000000000000000 RBX: ffff888102398c80 RCX: 0000000080190009
RDX: 0000000000000000 RSI: 000000000000006a RDI: 0000000000000000
RBP: ffff888102398c00 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000000ca R11: 0000000000015681 R12: 0000000000000001
R13: ffffc900002b0d68 R14: ffff88811115e000 R15: ffff8881107aca40
FS: 00007f41ded69500(0000) GS:ffff888667dc0000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556ccc2dc1a0 CR3: 0000000104fd8003 CR4: 0000000000772ef0
PKRU: 55555554
Call Trace:
<IRQ>
? die+0x32/0x80
? do_trap+0xd9/0x100
? dql_completed+0x26b/0x290
? dql_completed+0x26b/0x290
? do_error_trap+0x6d/0xb0
? dql_completed+0x26b/0x290
? exc_invalid_op+0x4c/0x60
? dql_completed+0x26b/0x290
? asm_exc_invalid_op+0x16/0x20
? dql_completed+0x26b/0x290
__free_old_xmit+0xff/0x170 [virtio_net]
free_old_xmit+0x54/0xc0 [virtio_net]
virtnet_poll+0xf4/0xe30 [virtio_net]
? __update_load_avg_cfs_rq+0x264/0x2d0
? update_curr+0x35/0x260
? reweight_entity+0x1be/0x260
__napi_poll.constprop.0+0x28/0x1c0
net_rx_action+0x329/0x420
? enqueue_hrtimer+0x35/0x90
? trace_hardirqs_on+0x1d/0x80
? kvm_sched_clock_read+0xd/0x20
? sched_clock+0xc/0x30
? kvm_sched_clock_read+0xd/0x20
? sched_clock+0xc/0x30
? sched_clock_cpu+0xd/0x1a0
handle_softirqs+0x138/0x3e0
do_softirq.part.0+0x89/0xc0
</IRQ>
<TASK>
__local_bh_enable_ip+0xa7/0xb0
virtnet_open+0xc8/0x310 [virtio_net]
__dev_open+0xfa/0x1b0
__dev_change_flags+0x1de/0x250
dev_change_flags+0x22/0x60
do_setlink.isra.0+0x2df/0x10b0
? rtnetlink_rcv_msg+0x34f/0x3f0
? netlink_rcv_skb+0x54/0x100
? netlink_unicast+0x23e/0x390
? netlink_sendmsg+0x21e/0x490
? ____sys_sendmsg+0x31b/0x350
? avc_has_perm_noaudit+0x67/0xf0
? cred_has_capability.isra.0+0x75/0x110
? __nla_validate_parse+0x5f/0xee0
? __pfx___probestub_irq_enable+0x3/0x10
? __create_object+0x5e/0x90
? security_capable+0x3b/0x70
rtnl_newlink+0x784/0xaf0
? avc_has_perm_noaudit+0x67/0xf0
? cred_has_capability.isra.0+0x75/0x110
? stack_depot_save_flags+0x24/0x6d0
? __pfx_rtnl_newlink+0x10/0x10
rtnetlink_rcv_msg+0x34f/0x3f0
? do_syscall_64+0x6c/0x180
? entry_SYSCALL_64_after_hwframe+0x76/0x7e
? __pfx_rtnetlink_rcv_msg+0x10/0x10
netlink_rcv_skb+0x54/0x100
netlink_unicast+0x23e/0x390
netlink_sendmsg+0x21e/0x490
____sys_sendmsg+0x31b/0x350
? copy_msghdr_from_user+0x6d/0xa0
___sys_sendmsg+0x86/0xd0
? __pte_offset_map+0x17/0x160
? preempt_count_add+0x69/0xa0
? __call_rcu_common.constprop.0+0x147/0x610
? preempt_count_add+0x69/0xa0
? preempt_count_add+0x69/0xa0
? _raw_spin_trylock+0x13/0x60
? trace_hardirqs_on+0x1d/0x80
__sys_sendmsg+0x66/0xc0
do_syscall_64+0x6c/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f41defe5b34
Code: 15 e1 12 0f 00 f7 d8 64 89 02 b8 ff ff ff ff eb bf 0f 1f 44 00 00
f3 0f 1e fa 80 3d 35 95 0f 00 00 74 13 b8 2e 00 00 00 0f 05 <48> 3d 00
f0 ff ff 77 4c c3 0f 1f 00 55 48 89 e5 48 83 ec 20 89 55
RSP: 002b:00007ffe5336ecc8 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f41defe5b34
RDX: 0000000000000000 RSI: 00007ffe5336ed30 RDI: 0000000000000003
RBP: 00007ffe5336eda0 R08: 0000000000000010 R09: 0000000000000001
R10: 00007ffe5336f6f9 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000067452259 R14: 0000556ccc28b040 R15: 0000000000000000
</TASK>
[...]
---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
Fixes: c8bd1f7f3e61 ("virtio_net: add support for Byte Queue Limits")
Cc: <stable@xxxxxxxxxxxxxxx> # v6.11+
Signed-off-by: Koichiro Den <koichiro.den@xxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 37 +++++++++++++++++++++++++++++--------
1 file changed, 29 insertions(+), 8 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 64c87bb48a41..3e36c0470600 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -513,7 +513,7 @@ static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
struct sk_buff *curr_skb,
struct page *page, void *buf,
int len, int truesize);
-static void virtnet_xsk_completed(struct send_queue *sq, int num);
+static void virtnet_xsk_completed(struct send_queue *sq, int num, bool drain);
enum virtnet_xmit_type {
VIRTNET_XMIT_TYPE_SKB,
@@ -580,7 +580,8 @@ static void sg_fill_dma(struct scatterlist *sg, dma_addr_t addr, u32 len)
}
static void __free_old_xmit(struct send_queue *sq, struct netdev_queue *txq,
- bool in_napi, struct virtnet_sq_free_stats *stats)
+ bool in_napi, struct virtnet_sq_free_stats *stats,
+ bool drain)
{
struct xdp_frame *frame;
struct sk_buff *skb;
@@ -620,7 +621,8 @@ static void __free_old_xmit(struct send_queue *sq, struct netdev_queue *txq,
break;
}
}
- netdev_tx_completed_queue(txq, stats->napi_packets, stats->napi_bytes);
+ if (!drain)
+ netdev_tx_completed_queue(txq, stats->napi_packets, stats->napi_bytes);
}
static void virtnet_free_old_xmit(struct send_queue *sq,
@@ -628,10 +630,21 @@ static void virtnet_free_old_xmit(struct send_queue *sq,
bool in_napi,
struct virtnet_sq_free_stats *stats)
{
- __free_old_xmit(sq, txq, in_napi, stats);
+ __free_old_xmit(sq, txq, in_napi, stats, false);
if (stats->xsk)
- virtnet_xsk_completed(sq, stats->xsk);
+ virtnet_xsk_completed(sq, stats->xsk, false);
+}
+
+static void virtnet_drain_old_xmit(struct send_queue *sq,
+ struct netdev_queue *txq)
+{
+ struct virtnet_sq_free_stats stats = {0};
+
+ __free_old_xmit(sq, txq, false, &stats, true);
+
+ if (stats.xsk)
+ virtnet_xsk_completed(sq, stats.xsk, true);
}
/* Converting between virtqueue no. and kernel tx/rx queue no.
@@ -1499,7 +1512,8 @@ static bool virtnet_xsk_xmit(struct send_queue *sq, struct xsk_buff_pool *pool,
/* Avoid to wakeup napi meanless, so call __free_old_xmit instead of
* free_old_xmit().
*/
- __free_old_xmit(sq, netdev_get_tx_queue(dev, sq - vi->sq), true, &stats);
+ __free_old_xmit(sq, netdev_get_tx_queue(dev, sq - vi->sq), true,
+ &stats, false);
if (stats.xsk)
xsk_tx_completed(sq->xsk_pool, stats.xsk);
@@ -1556,10 +1570,13 @@ static int virtnet_xsk_wakeup(struct net_device *dev, u32 qid, u32 flag)
return 0;
}
-static void virtnet_xsk_completed(struct send_queue *sq, int num)
+static void virtnet_xsk_completed(struct send_queue *sq, int num, bool drain)
{
xsk_tx_completed(sq->xsk_pool, num);
+ if (drain)
+ return;
+
/* If this is called by rx poll, start_xmit and xdp xmit we should
* wakeup the tx napi to consume the xsk tx queue, because the tx
* interrupt may not be triggered.
@@ -3041,6 +3058,7 @@ static void virtnet_disable_queue_pair(struct virtnet_info *vi, int qp_index)
static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
{
+ struct netdev_queue *txq = netdev_get_tx_queue(vi->dev, qp_index);
struct net_device *dev = vi->dev;
int err;
@@ -3054,7 +3072,10 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
if (err < 0)
goto err_xdp_reg_mem_model;
- netdev_tx_reset_queue(netdev_get_tx_queue(vi->dev, qp_index));
+ /* Drain any unconsumed TX skbs transmitted before the last virtnet_close */
+ virtnet_drain_old_xmit(&vi->sq[qp_index], txq);
+
+ netdev_tx_reset_queue(txq);
virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);
virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi);
--
2.43.0
