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From: Jason Wang <jasowang@redhat.com>
Date: Thu, 11 Apr 2024 16:47:29 +0800
Message-ID: <CACGkMEsjTD7Q26BqLuRMh7QmRZYeWZuTbQSDrb7O=uny5oknTg@mail.gmail.com>
Subject: Re: [PATCH v2] net:tun: limit printing rate when illegal packet
 received by tun dev
To: Paolo Abeni <pabeni@redhat.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>, netdev@vger.kernel.org, 
	linux-kernel@vger.kernel.org, Lei Chen <lei.chen@smartx.com>, 
	"David S. Miller" <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, 
	Jakub Kicinski <kuba@kernel.org>
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On Thu, Apr 11, 2024 at 4:30=E2=80=AFPM Paolo Abeni <pabeni@redhat.com> wro=
te:
>
> 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.

I think the fix should be

ef3db4a59542 ("tun: avoid BUG, dump packet on GSO errors")

The target should be net.

And it needs to address Williem's concern about patch format.

With those fixed.

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks

>
> Thanks,
>
> Paolo
>