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Wed, 27 May 2026 07:05:27 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay03.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 64R75OHm57409810 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 May 2026 07:05:24 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8A9DC20043; Wed, 27 May 2026 07:05:24 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 468F320040; Wed, 27 May 2026 07:05:21 +0000 (GMT) Received: from [9.39.21.117] (unknown [9.39.21.117]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 27 May 2026 07:05:21 +0000 (GMT) Message-ID: Date: Wed, 27 May 2026 12:35:20 +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: [BUG] sched/cache: "Make LLC id continuous" causes NULL cpumask dereference in build_sched_domains on POWER9 To: Venkat Rao Bagalkote Cc: Madhavan Srinivasan , Ritesh Harjani , "Christophe Leroy (CS GROUP)" , LKML , linuxppc-dev , linux-sched@vger.kernel.org, tim.c.chen@linux.intel.com, K Prateek Nayak , Peter Zijlstra , "Chen, Yu C" , Srikar Dronamraju References: <51154de7-3700-4cb4-82f2-1b3a8fa427f7@linux.ibm.com> <8675afde-5c7f-4717-be7a-a473bd1af381@linux.ibm.com> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: <8675afde-5c7f-4717-be7a-a473bd1af381@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: o36wkTYfmX6wkg53Xz2lLR8nf0TE3yUT X-Proofpoint-ORIG-GUID: o36wkTYfmX6wkg53Xz2lLR8nf0TE3yUT X-Authority-Analysis: v=2.4 cv=QIJYgALL c=1 sm=1 tr=0 ts=6a1697b8 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=QyXUC8HyAAAA:8 a=Vc7GBhowq85ZZSl4faYA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTI3MDA2MiBTYWx0ZWRfX3qzY6zTHIpWp e/6FccgoVaINBGawA/Uabhyy8A6e+mULpK8QGKT3s2v0ivXsW3v4SaX1K6lxY2RavxPckP/UG1Q e68sCEjOrgWeSC07NPI4AT/22STdbxUGt5/irfkPEKXY6DvWG7u04ho0MYfoyr/FBzoqc9maQ2u D4bySOsHPbzJL5JyusuaKtp2mTP7A3kZtMzRLe15AzPCj2t3EITJFvbJYWaspg5uh5Ez+yBLE6h DI4q8K4xDSRKm6nnTrHuGlG7reoKsK8WZz5ft01hIJXlLzkGatNhwBnv5uuWXMocFXKJHFLEl7z GUXO40RVuqvuIYDw5DRGmYaPuPA9NnIVD+G1CZR0D2XyzF/JVs9gSvonpu+DtQ8Rk1DIO6tNjXf j6IsSm00BRRrz+7JW64wX1e2H8p+ClGzmScMj2iGK6nNHCNY7bnl4lELZcOfAD7K/8IcgQcsl4J YWMhH0GjHPHdbAs1oIA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-05-26_05,2026-05-26_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 priorityscore=1501 impostorscore=0 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 adultscore=0 spamscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605270062 On 5/26/26 10:54 AM, Venkat Rao Bagalkote wrote: > > On 26/05/26 9:38 am, Chen, Yu C wrote: >> Hi Venkat, >> >> On 5/26/2026 11:14 AM, Srikar Dronamraju wrote: >>> * Chen, Yu C [2026-05-25 23:35:45]: >>> >>>> Hi Venkat, >>>> >>>> On 5/25/2026 10:07 PM, Venkat Rao Bagalkote wrote: >>>>> Greetings!!! >>>>> >>>>> I am seeing an early boot kernel panic due to NULL pointer dereference >>>>> on a POWER9 (pSeries) system when testing linux-next (next-20260522). > > > This issue is seen on P11 as well. > > [    0.006697] smp: Brought up 1 node, 16 CPUs > [    0.006702] Big cores detected but using small core scheduling > [    0.006752] BUG: Kernel NULL pointer dereference on read at 0x00000000 > [    0.006755] Faulting instruction address: 0xc000000020adbb6c > [    0.006759] Oops: Kernel access of bad area, sig: 7 [#1] > [    0.006762] LE PAGE_SIZE=4K MMU=Radix  SMP NR_CPUS=8192 NUMA pSeries > [    0.006767] Modules linked in: > [    0.006772] CPU: 4 UID: 0 PID: 1 Comm: swapper/4 Not tainted 7.1.0- > rc5-next-20260525 #1 PREEMPT(lazy) > [    0.006777] Hardware name: IBM,9080-HEX Power11 (architected) > 0x820200 0xf000007 of:IBM,FW1110.01 (NH1110_069) hv:phyp pSeries > [    0.006781] NIP:  c000000020adbb6c LR: c0000000202e5a58 CTR: > 0000000000000000 > [    0.006784] REGS: c0000000283d7890 TRAP: 0300   Not tainted (7.1.0- > rc5-next-20260525) > [    0.006788] MSR:  8000000002009033   CR: > 44002242  XER: 20040003 > [    0.006796] CFAR: c0000000202e5a54 DAR: 0000000000000000 DSISR: > 00080000 IRQMASK: 0 > [    0.006796] GPR00: 0000000000000000 c0000000283d7b50 c000000021abf100 > 0000000000000010 > [    0.006796] GPR04: 0000000000000010 0000000000000030 0000000000000000 > c000000028365500 > [    0.006796] GPR08: 0000000000000000 c000000022213598 000000003b77d000 > 0000000000000000 > [    0.006796] GPR12: c00000002005d8f0 c000000000008000 c0000000283cb578 > c0000000283cb400 > [    0.006796] GPR16: c0000000283c9000 c000000022218b20 c0000000222330e8 > 00000000ffffffff > [    0.006796] GPR20: fffffffffffffff6 0000000000000000 c000000022da36e0 > 0000000000000000 > [    0.006796] GPR24: 0000000000000000 0000000000000000 c0000000283c9178 > c0000000227b5f00 > [    0.006796] GPR28: c00000002831c1e8 c000000022db5980 0000000000000000 > 0000000000000000 > [    0.006835] NIP [c000000020adbb6c] _find_first_bit+0xc/0xc0 > [    0.006842] LR [c0000000202e5a58] build_sched_domains+0x7d8/0xb40 > [    0.006847] Call Trace: > [    0.006849] [c0000000283d7b50] [c0000000202e5408] > build_sched_domains+0x188/0xb40 (unreliable) > [    0.006854] [c0000000283d7c90] [c000000022034380] > sched_init_domains+0x118/0x168 > [    0.006860] [c0000000283d7ce0] [c000000022032b14] > sched_init_smp+0xa8/0x158 > [    0.006865] [c0000000283d7d30] [c000000022005674] > kernel_init_freeable+0x1ac/0x294 > [    0.006870] [c0000000283d7dd0] [c000000020011718] kernel_init+0x2c/0x1c4 > [    0.006874] [c0000000283d7e30] [c00000002000debc] > ret_from_kernel_user_thread+0x14/0x1c > [    0.006878] ---- interrupt: 0 at 0x0 > [    0.006881] Code: eb610038 7fc3f378 eb810040 eba10048 38210060 > ebc1fff0 ebe1fff8 7c0803a6 4e800020 7c681b78 7c832379 4d820020 > 38e3ffff 39400000 78e7d7e2 > [    0.006895] ---[ end trace 0000000000000000 ]--- > [    0.006898] > > > Regards, > > Venkat. > Venkat, Was it on P11 on Shared LPAR?