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

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Date: Thu, 11 Apr 2024 18:33:06 +0800
From: Lei Chen <lei.chen@...rtx.com>
To: Jason Wang <jasowang@...hat.com>
Cc: Paolo Abeni <pabeni@...hat.com>, Willem de Bruijn <willemdebruijn.kernel@...il.com>, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH v2] net:tun: limit printing rate when illegal packet
 received by tun dev

On Thu, Apr 11, 2024 at 4:47 PM Jason Wang <jasowang@...hat.com> wrote:
>
> On Thu, Apr 11, 2024 at 4:30 PM Paolo Abeni <pabeni@...hat.com> wrote:
> >
> > 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@...rtx.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@...hat.com>

Thanks for your help.
I will remake the patch with subject-prefix "PATCH net-next v3"  and
fix tag ef3db4a59542"