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McKenney" Cc: Boqun Feng , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Uladzislau Rezki , rcu@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Samir M , Srikar Dronamraju Subject: Re: BUG: workqueue lockup - SRCU schedules work on not-online CPUs during size transition Message-ID: References: <073abb55-197a-4519-b177-f9f776624fed@paulmck-laptop> <024e1e59-c901-4494-9935-f6871af88b2d@paulmck-laptop> <2157a59f-a1d3-4007-b8ce-3a7b0e0b9057@paulmck-laptop> <022fe334-1c53-41f1-94cd-96140b2f9cdf@paulmck-laptop> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <022fe334-1c53-41f1-94cd-96140b2f9cdf@paulmck-laptop> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=AqDeGu9P c=1 sm=1 tr=0 ts=69f24cad cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=NR5ev6yDxV4NLjt8mV4A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDI5MDE4NCBTYWx0ZWRfX+C1w57xVNpc3 TjBsE/YOaoqUZcHEGnDZOq+iIvGE9yM60SffvQBBkKN7na5/hwN8pjlhqFgSEJHYnPM5AvWF+h4 lkRGsGreAwaTXlGHfvfBVG/8KO917Zqzchuz3dko7RHFTHNkrYZ9tn+gUoQf9V1RZLtBQO348PV a6slvDWFw32pWY2e4HhANhG756BmLfkEm6RltlwWtufydlWisx5Mq4O4N2MjU8Ox0Ljas8x4N1y DpmtPPrls3E1uW0vJYvdKIBSphYOI8qSaWvrseAOcf+TZrKUv88zlBWDg8b1azOnTw33SHlZMpW pPANi/UyVLuQxnIm+wxgGKwejumrANGkkkbV0wHzf44r3DDrUhIfhYTSCrk8epKMJYpvdcZVXyV oEoIVI7Y/hHrbLaRmgpfRRpW/TCnkMo75eRuKphL9Z8vh7d7DQL5oetIbPZuaj7PzE2t+whXpai Fw1AgzEKpzIKDT7h8Ug== X-Proofpoint-GUID: R9WBkUSRa7-JAuxWi1uVPoI4oKH-GfyS X-Proofpoint-ORIG-GUID: gQMOXejSNUXphDVRbOWUpW5z5BfQTHoF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-29_01,2026-04-28_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 phishscore=0 suspectscore=0 clxscore=1015 lowpriorityscore=0 spamscore=0 bulkscore=0 impostorscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2604290184 On Wed, Apr 29, 2026 at 11:05:02AM -0700, Paul E. McKenney wrote: > On Wed, Apr 29, 2026 at 07:50:31PM +0200, Vasily Gorbik wrote: > > On Tue, Apr 14, 2026 at 12:24:12PM -0700, Paul E. McKenney wrote: > > > On Thu, Apr 09, 2026 at 09:03:26PM -0700, Paul E. McKenney wrote: > > > Please see below for the full patch, including refraining from queueing > > > workqueue handlers on not-yet-online CPUs and diverting SRCU callbacks > > > from not-yet-fully-online CPUs to the boot CPU's callback queue. > > ... > > > commit ce533a60b2ef29a9b516cc717e77c6b679bc09c0 > > > Author: Paul E. McKenney > > > Date: Thu Apr 9 11:16:02 2026 -0700 > > > > > > srcu: Don't queue workqueue handlers to never-online CPUs > > > ... > > > > > > Reported-by: Vasily Gorbik > > > Signed-off-by: Paul E. McKenney > > > Tested-by: Vasily Gorbik > > > Cc: Tejun Heo > > > > I retested it on s390 and on x86 KVM with --smp 16,maxcpus=255, all > > looks good to me. > > > > FWIW, again: > > > > Tested-by: Vasily Gorbik > > > > Would you mind adding Cc: stable so it gets picked up for v7.0? > > 61bbcfb50514 ("srcu: Push srcu_node allocation to GP when > > non-preemptible") is what made it reproducible for us. > > > > Thank you! > > And thank you for testing it, plus apologies for the hassle! > > At my next rebase, I will add the following: > > Fixes: 61bbcfb50514 ("srcu: Push srcu_node allocation to GP when non-preemptible") > Tested-by: Vasily Gorbik > > That should pull it into the needed -stable releases. > > Seem reasonable? Perfect, thanks Paul!