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[66.111.4.227]) by smtp.gmail.com with ESMTPSA id ge9-20020a05622a5c8900b003a7e38055c9sm10875572qtb.63.2023.01.13.09.58.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Jan 2023 09:58:17 -0800 (PST) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailauth.nyi.internal (Postfix) with ESMTP id 8AD5627C005A; Fri, 13 Jan 2023 12:58:17 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Fri, 13 Jan 2023 12:58:17 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrleekgddutdefucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepuehoqhhu nhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucggtffrrg htthgvrhhnpeehudfgudffffetuedtvdehueevledvhfelleeivedtgeeuhfegueeviedu ffeivdenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe gsohhquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdeiledvgeehtdei gedqudejjeekheehhedvqdgsohhquhhnrdhfvghngheppehgmhgrihhlrdgtohhmsehfih igmhgvrdhnrghmvg X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 13 Jan 2023 12:58:16 -0500 (EST) Date: Fri, 13 Jan 2023 09:58:10 -0800 From: Boqun Feng To: Hillf Danton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Peter Zijlstra , "Paul E. McKenney" , Paolo Bonzini , Joel Fernandes Subject: Re: [PATCH 2/3] rcu: Equip sleepable RCU with lockdep dependency graph checks Message-ID: References: <20230113065955.815667-1-boqun.feng@gmail.com> <20230113130330.1027-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230113130330.1027-1-hdanton@sina.com> X-Rspamd-Queue-Id: 62DE51C000A X-Stat-Signature: w45qpg7i3jg84c3tk8ra7x1ah43fuyrq X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1673632699-452083 X-HE-Meta: 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 FlPVDhUH W99IhAhD6jLe8GGXSsn7THzeNOkBgq912pPqKCmPIdq1A61LVSRbj4JuiF9DQNV8xTEgl99IrzibuBqLBo1cW0SPN+6x08uIHQtX0m/72wrjOySCAiHSKlai3Nw== 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 Fri, Jan 13, 2023 at 09:03:30PM +0800, Hillf Danton wrote: > 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 But isn't it just the srcu_mutex_ABBA test case in patch #3, and my run of lockdep selftest shows we can catch it. Anything subtle I'm missing? Regards, Boqun