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Thu, 11 Sep 2025 14:44:01 +0000 (GMT) Message-ID: Date: Thu, 11 Sep 2025 20:14:00 +0530 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v3 04/10] sched/core: Dont allow to use CPU marked as paravirt To: K Prateek Nayak Cc: vschneid@redhat.com, iii@linux.ibm.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com, vineeth@bitbyteword.org, jgross@suse.com, pbonzini@redhat.com, seanjc@google.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, tglx@linutronix.de, yury.norov@gmail.com, maddy@linux.ibm.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, gregkh@linuxfoundation.org References: <20250910174210.1969750-1-sshegde@linux.ibm.com> <20250910174210.1969750-5-sshegde@linux.ibm.com> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: SkhAT8dwWp3xYdrSKglBLTnRj3rEx9CF X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTA2MDIzNSBTYWx0ZWRfX0WPEwdPIlM/h 3C8gF6nm0Xt2OivrMr40D+CwrQoEKG3xQ679XIspDjcalc79FIPMR7Fl6NuVT6dKEVpndRPbrvk L573ASuh+rwL50MVCHjVqiqNfQ6gmyXwRU/5hy7RjKU57KUKdM2RuqoRyqCALHrzgpfPMoZDEFV vnEdFYRtA/hg7UCOphkSNvG+ob94oT19Uz/Vxsdgw/r3+18izq8P2Y3LFcbhmVN7QVhJHCizEhX +gtq9h197gXtKiPFJqsNIZe2wxbfELY0iW+CGyPEZYugwJvZVMeaGQp2FYrswwwMLK8UKQGMOEZ 0x9GJdtPwgslDbLQfaCClnyZw3T41FI5nOFDdPtt7rPox4I6HTP7v2V/hzu75ENi3z0b1gnBpnr 8DXK0Uc4 X-Proofpoint-GUID: 5WcYnnhw3T4zSrOOSNGH9LPLvv8uTT_t X-Authority-Analysis: v=2.4 cv=F59XdrhN c=1 sm=1 tr=0 ts=68c2e042 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=uXBPIk7YWzXHA4pK:21 a=IkcTkHD0fZMA:10 a=yJojWOMRYYMA:10 a=Bjl5kDSpjRqkKk4bOxUA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-11_01,2025-09-11_02,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 clxscore=1015 impostorscore=0 bulkscore=0 adultscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509060235 On 9/11/25 10:46 AM, K Prateek Nayak wrote: > Hello Shrikanth, > Hi Prateek, Thanks for looking into this. > On 9/10/2025 11:12 PM, Shrikanth Hegde wrote: >> @@ -2462,8 +2462,13 @@ static inline bool is_cpu_allowed(struct task_struct *p, int cpu) >> return cpu_online(cpu); >> >> /* Non kernel threads are not allowed during either online or offline. */ >> - if (!(p->flags & PF_KTHREAD)) >> - return cpu_active(cpu); >> + if (!(p->flags & PF_KTHREAD)) { >> + /* A user thread shouldn't be allowed on a paravirt cpu */ >> + if (is_cpu_paravirt(cpu)) >> + return false; >> + else > > nit. redundant "else". I think this can be simplified as: > alright. > return !is_cpu_paravirt(cpu) && cpu_active(cpu); > >> + return cpu_active(cpu); >> + } >