From: Florian Westphal <fw@strlen.de>
To: Vakul Garg <vakul.garg@nxp.com>
Cc: Florian Westphal <fw@strlen.de>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: Help needed - Kernel lockup while running ipsec
Date: Tue, 20 Aug 2019 11:38:00 +0200 [thread overview]
Message-ID: <20190820093800.GN2588@breakpoint.cc> (raw)
In-Reply-To: <DB7PR04MB4620487074796FBC015AFD098BAB0@DB7PR04MB4620.eurprd04.prod.outlook.com>
Vakul Garg <vakul.garg@nxp.com> wrote:
>
>
> > -----Original Message-----
> > From: Florian Westphal <fw@strlen.de>
> > Sent: Tuesday, August 20, 2019 2:53 PM
> > To: Vakul Garg <vakul.garg@nxp.com>
> > Cc: Florian Westphal <fw@strlen.de>; netdev@vger.kernel.org
> > Subject: Re: Help needed - Kernel lockup while running ipsec
> >
> > Vakul Garg <vakul.garg@nxp.com> wrote:
> > > > > With kernel 4.14.122, I am getting a kernel softlockup while
> > > > > running single
> > > > static ipsec tunnel.
> > > > > The problem reproduces mostly after running 8-10 hours of ipsec
> > > > > encap
> > > > test (on my dual core arm board).
> > > > >
> > > > > I found that in function xfrm_policy_lookup_bytype(), the policy
> > > > > in variable
> > > > 'ret' shows refcnt=0 under problem situation.
> > > > > This creates an infinite loop in xfrm_policy_lookup_bytype() and
> > > > > hence the
> > > > lockup.
> > > > >
> > > > > Can some body please provide me pointers about 'refcnt'?
> > > > > Is it legitimate for 'refcnt' to become '0'? Under what condition
> > > > > can it
> > > > become '0'?
> > > >
> > > > Yes, when policy is destroyed and the last user calls
> > > > xfrm_pol_put() which will invoke call_rcu to free the structure.
> > >
> > > It seems that policy reference count never gets decremented during packet
> > ipsec encap.
> > > It is getting incremented for every frame that hits the policy.
> > > In setkey -DP output, I see refcnt to be wrapping around after '0'.
> >
> > Thats a bug. Does this affect 4.14 only or does this happen on current tree
> > as well?
>
> I am yet to try it on 4.19.
> Can you help me with the right fix? Which part of code should it get decremented?
> I am not conversant with xfrm code.
Normally policy reference counts get decremented when the skb is free'd, via dst
destruction (xfrm_dst_destroy()).
Do you see a dst leak as well?
next prev parent reply other threads:[~2019-08-20 9:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-19 12:55 Help needed - Kernel lockup while running ipsec Vakul Garg
2019-08-19 17:38 ` Florian Westphal
2019-08-20 9:10 ` Vakul Garg
2019-08-20 9:23 ` Florian Westphal
2019-08-20 9:26 ` Vakul Garg
2019-08-20 9:30 ` Vakul Garg
2019-08-20 9:38 ` Florian Westphal [this message]
2019-08-20 9:52 ` Vakul Garg
2019-08-20 10:38 ` Vakul Garg
2019-08-21 7:37 ` Vakul Garg
2019-08-21 16:11 ` Florian Westphal
2019-08-22 10:23 ` Vakul Garg
2019-08-22 11:21 ` [PATCH 4.14.y stable] xfrm: policy: remove pcpu policy cache Florian Westphal
2019-08-22 13:09 ` Greg KH
2019-08-22 13:37 ` Florian Westphal
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