netdev - Re: [net-next,v3] ipv6: shorten reassembly timeout under fragment memory pressure

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Message-ID: <CANn89i+mNojd9mUL_dt_=D+7nZ9xcV96CYJG_LYFmBZDOYUMFQ@mail.gmail.com>
Date: Wed, 11 Feb 2026 16:36:28 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Fernando Fernandez Mancera <fmancera@...e.de>
Cc: soukjin.bae@...sung.com, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, 
	"netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>, 
	"davem@...emloft.net" <davem@...emloft.net>, "pabeni@...hat.com" <pabeni@...hat.com>, 
	"dsahern@...nel.org" <dsahern@...nel.org>, "kuba@...nel.org" <kuba@...nel.org>, 
	"horms@...nel.org" <horms@...nel.org>, "phil@....cc" <phil@....cc>, 
	"coreteam@...filter.org" <coreteam@...filter.org>, "fw@...len.de" <fw@...len.de>, 
	"pablo@...filter.org" <pablo@...filter.org>
Subject: Re: [net-next,v3] ipv6: shorten reassembly timeout under fragment
 memory pressure

On Wed, Feb 11, 2026 at 4:11 PM Fernando Fernandez Mancera
<fmancera@...e.de> wrote:
>
> On 2/11/26 11:32 AM, 배석진 wrote:
> >   Changes in v3:
> > - Fix build bot error and warnings
> > - baseline update
> >
> >
> >
> >  From c7940e3dd728fdc58c8199bc031bf3f8f1e8a20f Mon Sep 17 00:00:00 2001
> > From: Soukjin Bae <soukjin.bae@...sung.com>
> > Date: Wed, 11 Feb 2026 11:20:23 +0900
> > Subject: [PATCH] ipv6: shorten reassembly timeout under fragment memory
> >   pressure
> >
> > Under heavy IPv6 fragmentation, incomplete fragment queues may persist
> > for the full reassembly timeout even when fragment memory is under
> > pressure.
> >
> > This can lead to prolonged retention of fragment queues that are unlikely
> > to complete, causing newly arriving fragmented packets to be dropped due
> > to memory exhaustion.
> >
> > Introduce an optional mechanism to shorten the IPv6 reassembly timeout
> > when fragment memory usage exceeds the low threshold. Different timeout
> > values are applied depending on the upper-layer protocol to balance
> > eviction speed and completion probability.
> >
> > Signed-off-by: Soukjin Bae <soukjin.bae@...sung.com>
>
> Hello,
>
> isn't this what net.ipv6.ip6frag_time does? In addition, the situation
> you described could be overcome by increasing the memory thresholds at
> net.ipv6.ip6frag_low_thresh and net.ipv6.ip6frag_high_thresh.
>
> Please, let me know if I am missing something.

Also :

1) net-next is closed.
Please read Documentation/process/maintainer-netdev.rst

2) We do not send 3 versions of a patch in the same day.
Please read Documentation/process/maintainer-netdev.rst

3) What about IPv4 ?

4) Only the first fragment contains the 'protocol of the whole
datagram', and fragments can be received in any order.

5) We do not add a MAINTAINER entry for such a patch, sorry.