[PATCH net v4 0/6] virtio_net: correct netdev_tx_reset_queue() invocation points

From: Koichiro Den
Date: Thu Dec 05 2024 - 20:12:08 EST

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When virtnet_close is followed by virtnet_open, some TX completions can
possibly remain unconsumed, until they are finally processed during the
first NAPI poll after the netdev_tx_reset_queue(), resulting in a crash
[1]. Commit b96ed2c97c79 ("virtio_net: move netdev_tx_reset_queue() call
before RX napi enable") was not sufficient to eliminate all BQL crash
scenarios for virtio-net.

This issue can be reproduced with the latest net-next master by running:
`while :; do ip l set DEV down; ip l set DEV up; done` under heavy network
TX load from inside the machine.

This patch series resolves the issue and also addresses similar existing
problems:

(a). Drop netdev_tx_reset_queue() from open/close path. This eliminates the
BQL crashes due to the problematic open/close path.

(b). As a result of (a), netdev_tx_reset_queue() is now explicitly required
in freeze/restore path. Add netdev_tx_reset_queue() immediately after
free_unused_bufs() invocation.

(c). Fix missing resetting in virtnet_tx_resize().
virtnet_tx_resize() has lacked proper resetting since commit
c8bd1f7f3e61 ("virtio_net: add support for Byte Queue Limits").

(d). Fix missing resetting in the XDP_SETUP_XSK_POOL path.
Similar to (c), this path lacked proper resetting. Call
netdev_tx_reset_queue() when virtqueue_reset() has actually recycled
unused buffers.

This patch series consists of six commits:
[1/6]: Resolves (a) and (b). # also -stable 6.11.y
[2/6]: Minor fix to make [4/6] streamlined.
[3/6]: Prerequisite for (c). # also -stable 6.11.y
[4/6]: Resolves (c) (incl. Prerequisite for (d)) # also -stable 6.11.y
[5/6]: Preresuisite for (d).
[6/6]: Resolves (d).

Changes for v4:
- move netdev_tx_reset_queue() out of free_unused_bufs()
- submit to net, not net-next
Changes for v3:
- replace 'flushed' argument with 'recycle_done'
Changes for v2:
- add tx queue resetting for (b) to (d) above

v3: https://lore.kernel.org/all/20241204050724.307544-1-koichiro.den@xxxxxxxxxxxxx/
v2: https://lore.kernel.org/all/20241203073025.67065-1-koichiro.den@xxxxxxxxxxxxx/
v1: https://lore.kernel.org/all/20241130181744.3772632-1-koichiro.den@xxxxxxxxxxxxx/

[1]:
------------[ 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/0x7[I0
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 ]---

Koichiro Den (6):
virtio_net: correct netdev_tx_reset_queue() invocation point
virtio_net: replace vq2rxq with vq2txq where appropriate
virtio_ring: add a func argument 'recycle_done' to virtqueue_resize()
virtio_net: ensure netdev_tx_reset_queue is called on tx ring resize
virtio_ring: add a func argument 'recycle_done' to virtqueue_reset()
virtio_net: ensure netdev_tx_reset_queue is called on bind xsk for tx

drivers/net/virtio_net.c | 31 +++++++++++++++++++++++++------
drivers/virtio/virtio_ring.c | 12 ++++++++++--
include/linux/virtio.h | 6 ++++--
3 files changed, 39 insertions(+), 10 deletions(-)

--
2.43.0

Next message: Koichiro Den: "[PATCH net v4 1/6] virtio_net: correct netdev_tx_reset_queue() invocation point"
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