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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 30 Aug 2018 13:37:41 -0400 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w7UHber220840494 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 30 Aug 2018 17:37:40 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 55DC4B2070; Thu, 30 Aug 2018 13:36:35 -0400 (EDT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 35461B2064; Thu, 30 Aug 2018 13:36:35 -0400 (EDT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.159]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 30 Aug 2018 13:36:35 -0400 (EDT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 2E6B016C1EDF; Thu, 30 Aug 2018 10:37:42 -0700 (PDT) Date: Thu, 30 Aug 2018 10:37:42 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, Tejun Heo Subject: Re: [PATCH tip/core/rcu 3/3] srcu: Make early-boot call_srcu() reuse workqueue lists Reply-To: paulmck@linux.vnet.ibm.com References: <20180829212036.GA22033@linux.vnet.ibm.com> <20180829212313.22903-3-paulmck@linux.vnet.ibm.com> <20180829215616.1c10e476@vmware.local.home> <20180830020701.GE4225@linux.vnet.ibm.com> <20180829224609.5ffdc9ec@vmware.local.home> <20180830032315.GG4225@linux.vnet.ibm.com> <20180830124444.6bb9faac@gandalf.local.home> <20180830173509.GL4225@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180830173509.GL4225@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18083017-0052-0000-0000-00000328BAC5 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009640; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000266; SDB=6.01081123; UDB=6.00557725; IPR=6.00861107; MB=3.00023020; MTD=3.00000008; XFM=3.00000015; UTC=2018-08-30 17:37:45 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18083017-0053-0000-0000-00005DE863D1 Message-Id: <20180830173742.GA17677@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-08-30_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1808300177 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 30, 2018 at 10:35:09AM -0700, Paul E. McKenney wrote: > On Thu, Aug 30, 2018 at 12:44:44PM -0400, Steven Rostedt wrote: > > On Wed, 29 Aug 2018 20:23:15 -0700 > > "Paul E. McKenney" wrote: > > > > > > > Glad you like it! Does it actually work for you? ;-) > > > > > > > > Oh, you want me to actually test it too? ;-) > > > > > > ;-) ;-) ;-) > > > > > > > I'll try to add that in my todo list tomorrow. > > > > > > Much appreciated! > > > > I reverted the change that prevents calling call_srcu() early: > > > > I checked out v4.19-rc1 and applied these three patches, then did: > > > > git show f8a79d5c7ef47c62d97a30e16064caf2ef91f648 | patch -p1 -R > > > > But still triggered the following: > > > > WARNING: CPU: 0 PID: 0 at /work/git/linux-trace.git/kernel/rcu/srcutree.c:242 check_init_srcu_struct+0x85/0x90 > > Gah!!! I needed to have removed that WARN_ON_ONCE(), didn't I? > In fact, I should have removed that once I started using workqueues, > quite some time back. As in the below patch. Thanx, Paul ------------------------------------------------------------------------ diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 75571ff09c62..a8846ed7f352 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -239,7 +239,6 @@ static void check_init_srcu_struct(struct srcu_struct *sp) { unsigned long flags; - WARN_ON_ONCE(rcu_scheduler_active == RCU_SCHEDULER_INIT); /* The smp_load_acquire() pairs with the smp_store_release(). */ if (!rcu_seq_state(smp_load_acquire(&sp->srcu_gp_seq_needed))) /*^^^*/ return; /* Already initialized. */