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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 1 Jul 2019 13:23:03 +0100 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x61CN2YM13304396 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 1 Jul 2019 12:23:02 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8F104B2064; Mon, 1 Jul 2019 12:23:02 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6DD10B205F; Mon, 1 Jul 2019 12:23:02 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.85.128.230]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 1 Jul 2019 12:23:02 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id E411A16C5D9E; Mon, 1 Jul 2019 05:23:05 -0700 (PDT) Date: Mon, 1 Jul 2019 05:23:05 -0700 From: "Paul E. McKenney" To: Sebastian Andrzej Siewior Cc: Peter Zijlstra , Scott Wood , Joel Fernandes , Steven Rostedt , rcu , LKML , Thomas Gleixner , Ingo Molnar , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan Subject: Re: [RFC] Deadlock via recursive wakeup via RCU with threadirqs Reply-To: paulmck@linux.ibm.com References: <20190627181638.GA209455@google.com> <20190627184107.GA26519@linux.ibm.com> <13761fee4b71cc004ad0d6709875ce917ff28fce.camel@redhat.com> <20190627203612.GD26519@linux.ibm.com> <20190628141522.GF3402@hirez.programming.kicks-ass.net> <20190628155404.GV26519@linux.ibm.com> <20190628160408.GH32547@worktop.programming.kicks-ass.net> <20190628172056.GW26519@linux.ibm.com> <20190701094215.GR3402@hirez.programming.kicks-ass.net> <20190701102442.35grdpcsbrwyyaco@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190701102442.35grdpcsbrwyyaco@linutronix.de> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19070112-0072-0000-0000-000004430B4F X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011359; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000286; SDB=6.01225887; UDB=6.00645332; IPR=6.01007099; MB=3.00027534; MTD=3.00000008; XFM=3.00000015; UTC=2019-07-01 12:23:06 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19070112-0073-0000-0000-00004CB34210 Message-Id: <20190701122305.GB26519@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-01_09:,, 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=833 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907010154 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 01, 2019 at 12:24:42PM +0200, Sebastian Andrzej Siewior wrote: > On 2019-07-01 11:42:15 [+0200], Peter Zijlstra wrote: > > I'm not sure if smp_send_reschedule() can be used as self-IPI, some > > hardware doesn't particularly like that IIRC. That is, hardware might > > only have interfaces to IPI _other_ CPUs, but not self. > > > > The normal scheduler code takes care to not call smp_send_reschedule() > > to self. > > and irq_work: > 471ba0e686cb1 ("irq_work: Do not raise an IPI when queueing work on the local CPU") OK, so it looks like I will need to use something else. But thank you for calling my attention to this commit. Thanx, Paul