Re: [PATCH v2] net:tun: limit printing rate when illegal packet received by tun dev

[Paolo Abeni <pabeni@redhat.com>]

On Wed, 2024-04-10 at 00:22 -0400, Lei Chen wrote:
> vhost_worker will call tun call backs to receive packets. If too many
> illegal packets arrives, tun_do_read will keep dumping packet contents.
> When console is enabled, it will costs much more cpu time to dump
> packet and soft lockup will be detected.
> 
> net_ratelimit mechanism can be used to limit the dumping rate.
> 
> PID: 33036    TASK: ffff949da6f20000  CPU: 23   COMMAND: "vhost-32980"
>  #0 [fffffe00003fce50] crash_nmi_callback at ffffffff89249253
>  #1 [fffffe00003fce58] nmi_handle at ffffffff89225fa3
>  #2 [fffffe00003fceb0] default_do_nmi at ffffffff8922642e
>  #3 [fffffe00003fced0] do_nmi at ffffffff8922660d
>  #4 [fffffe00003fcef0] end_repeat_nmi at ffffffff89c01663
>     [exception RIP: io_serial_in+20]
>     RIP: ffffffff89792594  RSP: ffffa655314979e8  RFLAGS: 00000002
>     RAX: ffffffff89792500  RBX: ffffffff8af428a0  RCX: 0000000000000000
>     RDX: 00000000000003fd  RSI: 0000000000000005  RDI: ffffffff8af428a0
>     RBP: 0000000000002710   R8: 0000000000000004   R9: 000000000000000f
>     R10: 0000000000000000  R11: ffffffff8acbf64f  R12: 0000000000000020
>     R13: ffffffff8acbf698  R14: 0000000000000058  R15: 0000000000000000
>     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
>  #5 [ffffa655314979e8] io_serial_in at ffffffff89792594
>  #6 [ffffa655314979e8] wait_for_xmitr at ffffffff89793470
>  #7 [ffffa65531497a08] serial8250_console_putchar at ffffffff897934f6
>  #8 [ffffa65531497a20] uart_console_write at ffffffff8978b605
>  #9 [ffffa65531497a48] serial8250_console_write at ffffffff89796558
>  #10 [ffffa65531497ac8] console_unlock at ffffffff89316124
>  #11 [ffffa65531497b10] vprintk_emit at ffffffff89317c07
>  #12 [ffffa65531497b68] printk at ffffffff89318306
>  #13 [ffffa65531497bc8] print_hex_dump at ffffffff89650765
>  #14 [ffffa65531497ca8] tun_do_read at ffffffffc0b06c27 [tun]
>  #15 [ffffa65531497d38] tun_recvmsg at ffffffffc0b06e34 [tun]
>  #16 [ffffa65531497d68] handle_rx at ffffffffc0c5d682 [vhost_net]
>  #17 [ffffa65531497ed0] vhost_worker at ffffffffc0c644dc [vhost]
>  #18 [ffffa65531497f10] kthread at ffffffff892d2e72
>  #19 [ffffa65531497f50] ret_from_fork at ffffffff89c0022f
> 
> Signed-off-by: Lei Chen <lei.chen@smartx.com>

This change is IMHO best suited for 'net': the possible soft sookup
looks nasty.

@Willem, @Jason, any strong opinion against the above?

Otherwise, @Lei Chen, please repost with a suitable fixes tag and
adding the target tree into the subj prefix.

Thanks,

Paolo