netdev - Re: Help needed - Kernel lockup while running ipsec

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Date:   Wed, 21 Aug 2019 18:11:59 +0200
From:   Florian Westphal <fw@...len.de>
To:     Vakul Garg <vakul.garg@....com>
Cc:     Florian Westphal <fw@...len.de>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: Help needed - Kernel lockup while running ipsec

Vakul Garg <vakul.garg@....com> wrote:
> > Policy refcount is decreasing properly on 4.19.
> > Same should be on the latest kernel too.
> 
> On kernel-4.14, I find dst_release() is getting called through xfrm_output_one().
> However since dst->__refcnt gets decremented to '1', 
> the call_rcu(&dst->rcu_head, dst_destroy_rcu) is not invoked. 
> 
> On kernel-4.19, dst->__refcnt gets decremented to '0', hence things fall in place and 
> dst_destroy_rcu() eventually executes.
> 
> Any further help/pointers for kernel-4.14 would be deeply appreciated.

Can you try getting rid of the pcpu dst cache?

I had a look at 4.14-stable and it at least lacks 2950278d2d04ff531.

I've attached an (untested) revert of the pcpu cache (its gone in 4.19
and onwards).



View attachment "0001-xfrm-policy-remove-pcpu-policy-cache.patch" of type "text/x-diff" (8995 bytes)