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McKenney" , Paolo Bonzini , Joel Fernandes Subject: Re: [PATCH 2/3] rcu: Equip sleepable RCU with lockdep dependency graph checks Date: Fri, 13 Jan 2023 21:03:30 +0800 Message-Id: <20230113130330.1027-1-hdanton@sina.com> In-Reply-To: <20230113065955.815667-3-boqun.feng@gmail.com> References: <20230113065955.815667-1-boqun.feng@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: os5qfayyh6mp3sr95o6owur17hdg83ou X-Rspamd-Queue-Id: C15FE20021 X-HE-Tag: 1673615030-171913 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 12 Jan 2023 22:59:54 -0800 Boqun Feng > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -1267,6 +1267,8 @@ static void __synchronize_srcu(struct srcu_struct *ssp, bool do_norm) > { > struct rcu_synchronize rcu; > > + srcu_lock_sync(&ssp->dep_map); > + > RCU_LOCKDEP_WARN(lockdep_is_held(ssp) || > lock_is_held(&rcu_bh_lock_map) || > lock_is_held(&rcu_lock_map) || > -- > 2.38.1 The following deadlock is able to escape srcu_lock_sync() because the __lock_release folded in sync leaves one lock on the sync side. cpu9 cpu0 --- --- lock A srcu_lock_acquire(&ssp->dep_map); srcu_lock_sync(&ssp->dep_map); lock A