On 9/26/24 02:03, Willem de Bruijn wrote:
greearb@ wrote:
From: Ben Greear greearb@candelatech.com
This reverts commit 504fc6f4f7f681d2a03aa5f68aad549d90eab853.
dev_queue_xmit_nit needs to run with bh locking, otherwise it conflicts with packets coming in from a nic in softirq context and packets being transmitted from user context.
================================ WARNING: inconsistent lock state 6.11.0 #1 Tainted: G W
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. btserver/134819 [HC0[0]:SC0[0]:HE1:SE1] takes: ffff8882da30c118 (rlock-AF_PACKET){+.?.}-{2:2}, at: tpacket_rcv+0x863/0x3b30 {IN-SOFTIRQ-W} state was registered at: lock_acquire+0x19a/0x4f0 _raw_spin_lock+0x27/0x40 packet_rcv+0xa33/0x1320 __netif_receive_skb_core.constprop.0+0xcb0/0x3a90 __netif_receive_skb_list_core+0x2c9/0x890 netif_receive_skb_list_internal+0x610/0xcc0 napi_complete_done+0x1c0/0x7c0 igb_poll+0x1dbb/0x57e0 [igb] __napi_poll.constprop.0+0x99/0x430 net_rx_action+0x8e7/0xe10 handle_softirqs+0x1b7/0x800 __irq_exit_rcu+0x91/0xc0 irq_exit_rcu+0x5/0x10 [snip]
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ----lock(rlock-AF_PACKET);
<Interrupt> lock(rlock-AF_PACKET);
*** DEADLOCK ***
Call Trace:
<TASK> dump_stack_lvl+0x73/0xa0 mark_lock+0x102e/0x16b0 __lock_acquire+0x9ae/0x6170 lock_acquire+0x19a/0x4f0 _raw_spin_lock+0x27/0x40 tpacket_rcv+0x863/0x3b30 dev_queue_xmit_nit+0x709/0xa40 vrf_finish_direct+0x26e/0x340 [vrf] vrf_l3_out+0x5f4/0xe80 [vrf] __ip_local_out+0x51e/0x7a0 [snip]
Fixes: 504fc6f4f7f6 ("vrf: Remove unnecessary RCU-bh critical section") Link: https://lore.kernel.org/netdev/05765015-f727-2f30-58da-2ad6fa7ea99f@candelat...
Signed-off-by: Ben Greear greearb@candelatech.com
Please Cc: all previous reviewers and folks who participated in the discussion. I entirely missed this. No need to add as Cc tags, just --cc in git send-email will do.
v2: Edit patch description.
drivers/net/vrf.c | 2 ++ net/core/dev.c | 1 + 2 files changed, 3 insertions(+)
diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 4d8ccaf9a2b4..4087f72f0d2b 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -608,7 +608,9 @@ static void vrf_finish_direct(struct sk_buff *skb) eth_zero_addr(eth->h_dest); eth->h_proto = skb->protocol;
rcu_read_lock_bh();rcu_read_unlock_bh();skb_pull(skb, ETH_HLEN); } diff --git a/net/core/dev.c b/net/core/dev.c index cd479f5f22f6..566e69a38eed 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2285,6 +2285,7 @@ EXPORT_SYMBOL_GPL(dev_nit_active); /*
- Support routine. Sends outgoing frames to any network
- taps currently in use.
- BH must be disabled before calling this.
Unnecessary. Especially patches for stable should be minimal to reduce the chance of conflicts.
I was asked to add this, and also asked to CC stable.
Thanks, Ben