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Date:   Thu, 3 Jun 2021 10:16:43 +0200
From:   Steffen Klassert <steffen.klassert@secunet.com>
To:     "Ahmed S. Darwish" <a.darwish@linutronix.de>
CC:     Varad Gautam <varad.gautam@suse.com>,
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        "Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: Re: [PATCH v2] xfrm: policy: Read seqcount outside of rcu-read side
 in xfrm_policy_lookup_bytype
Message-ID: <20210603081643.GW40979@gauss3.secunet.de>
References: <20210528120357.29542-1-varad.gautam@suse.com>
 <20210528160407.32127-1-varad.gautam@suse.com>
 <YLEd9RS8Cebjv2ho@lx-t490>
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On Fri, May 28, 2021 at 06:44:37PM +0200, Ahmed S. Darwish wrote:
> On Fri, May 28, 2021, Varad Gautam wrote:
> >
> > Thead 1 (xfrm_hash_resize)	Thread 2 (xfrm_policy_lookup_bytype)
> >
> > 				rcu_read_lock();
> > mutex_lock(&hash_resize_mutex);
> > 				read_seqcount_begin(&xfrm_policy_hash_generation);
> > 				mutex_lock(&hash_resize_mutex); // block
> > xfrm_bydst_resize();
> > synchronize_rcu(); // block
> > 		<RCU stalls in xfrm_policy_lookup_bytype>
> >
> ...
> >
> > Fixes: 77cc278f7b20 ("xfrm: policy: Use sequence counters with associated lock")
> > Signed-off-by: Varad Gautam <varad.gautam@suse.com>
> 
> Acked-by: Ahmed S. Darwish <a.darwish@linutronix.de>

Applied, thanks a lot!