6.11-stable review patch. If anyone has any objections, please let me know.
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From: Willem de Bruijn willemb@google.com
commit b04c4d9eb4f25b950b33218e33b04c94e7445e51 upstream.
This reverts commit 504fc6f4f7f681d2a03aa5f68aad549d90eab853.
dev_queue_xmit_nit is expected to be called with BH disabled. __dev_queue_xmit has the following:
/* Disable soft irqs for various locks below. Also * stops preemption for RCU. */ rcu_read_lock_bh();
VRF must follow this invariant. The referenced commit removed this protection. Which triggered a lockdep warning:
================================ 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 [...]
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 [...]
Fixes: 504fc6f4f7f6 ("vrf: Remove unnecessary RCU-bh critical section") Link: https://lore.kernel.org/netdev/20240925185216.1990381-1-greearb@candelatech.... Reported-by: Ben Greear greearb@candelatech.com Signed-off-by: Willem de Bruijn willemb@google.com Cc: stable@vger.kernel.org Reviewed-by: Ido Schimmel idosch@nvidia.com Tested-by: Ido Schimmel idosch@nvidia.com Reviewed-by: David Ahern dsahern@kernel.org Link: https://patch.msgid.link/20240929061839.1175300-1-willemdebruijn.kernel@gmai... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/vrf.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -607,7 +607,9 @@ static void vrf_finish_direct(struct sk_ eth_zero_addr(eth->h_dest); eth->h_proto = skb->protocol;
+ rcu_read_lock_bh(); dev_queue_xmit_nit(skb, vrf_dev); + rcu_read_unlock_bh();
skb_pull(skb, ETH_HLEN); }