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McKenney" To: David Woodhouse Cc: Christian Borntraeger , Peter Zijlstra , mhillenb@amazon.de, linux-kernel , kvm Subject: Re: [RFC] Make need_resched() return true when rcu_urgent_qs requested Reply-To: paulmck@linux.vnet.ibm.com References: <20180711210828.GD3593@linux.vnet.ibm.com> <1531396842.8759.125.camel@infradead.org> <20180712125351.GP3593@linux.vnet.ibm.com> <20180712161704.GA20726@linux.vnet.ibm.com> <20180716154015.GA21419@linux.vnet.ibm.com> <1531815548.19223.23.camel@infradead.org> <20180717125653.GH12945@linux.vnet.ibm.com> <20180718153628.GA24359@linux.vnet.ibm.com> <1531929711.3414.29.camel@infradead.org> <20180718163712.GB12945@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180718163712.GB12945@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18071917-0040-0000-0000-000004514700 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009393; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000266; SDB=6.01063136; UDB=6.00545913; IPR=6.00840987; MB=3.00022208; MTD=3.00000008; XFM=3.00000015; UTC=2018-07-19 17:09:55 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18071917-0041-0000-0000-000008577403 Message-Id: <20180719170953.GA17730@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-07-19_06:,, 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=830 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1807190180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 18, 2018 at 09:37:12AM -0700, Paul E. McKenney wrote: > On Wed, Jul 18, 2018 at 06:01:51PM +0200, David Woodhouse wrote: > > On Wed, 2018-07-18 at 08:36 -0700, Paul E. McKenney wrote: > > > And I finally did get some near misses from an earlier commit, so we > > > should consider your patch to be officially off the hook. > > > > Yay, I like it when it's not my fault. I'll redo it with the ifdef > > CONFIG_NO_HZ_FULL. > > Hey, I didn't say it wasn't your fault, only that it -officially- wasn't > your fault. ;-) And I believe that I found my bug in this commit (lots more testing still required, but the preponderance of evidence and all that): 2cc0c7f07143 ("rcu: Eliminate ->rcu_qs_ctr from the rcu_dynticks structure") So it really isn't your fault. Of course, the real reason for the lack of fault on your part will not because I believe I found the bug elsewhere, but instead because I will be dropping your patch (and mine as well) on Frederic's advice. ;-) Thanx, Paul