From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DA8CA3AC0DC for ; Mon, 1 Jun 2026 13:34:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780320844; cv=none; b=khIkn3zmQrWdM20UOKFbR1gTxRWn6ZU14Ttg7N63ZKQ7tuf0hWHzC1nXCWaC2wPD+ieGqKVUU9HEWoRUi6vVzp1/JftgLpG9CgTBZoe4uD8xDTVZ6npFwbFJzVfLAR8C4UF7WL4YXkLDOCqLkfsKOwThOipaF3Tbhq6LxaDQYB4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780320844; c=relaxed/simple; bh=6RlU2mCVMitBZVKfjN/8bFp6F9Eo+ueHoqZlR45XZAQ=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=ZSIp8j3G4XOEHiqyqc5QuF2Dm+KvAzEHE29pz/qTxkMicKyvuAGJx99KNd/VW5/H+y3lZ1/8ZYSYi89in/j+JDkk+6FZLQ8DmnDqZfy3o+JQPYx0pt7N7apsmBK9epKI+ALcKpuUW1k7kUkNgy/KK7ZCN9jfpvCdNdOnCExH3YI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=SHgvOqbb; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="SHgvOqbb" Received: from pps.filterd (m0353729.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 65170EO81588111; Mon, 1 Jun 2026 13:33:41 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=8ZIy6W i18e6wAh1yTcZ8JF6TEQ2IdsUD1HFotCg4S1s=; b=SHgvOqbbAdJA83bL56zj57 fNaIyLH8HcP5WGiKbvHDBTA9/s1xOItZFSIv5Ceb/aDJqpUXXB9YPsPKxqQHh/TL Y9BCs+VS3nmzONmUXwE9MQAj0WBeLsc9HzhrEMvvWamFKOaBM9zvvdF+5tozjGWu Odf767K4pjeMSg24NByRLFG73GkWDukkt6tgAqp6mlU82rcF45JBVqbQa4oe5651 LOpfIllvhFMj7vl+bez4HnuZxWKGZ0siw38gzRN+eTBnqQXeLsE50pxC9oTAhTcv aOqRBMfZegeS4qQXx+WQcDvesHQcy7vBeuhAV3eJOfqsAqIkvpKFZ1PUdM88ndkg == Received: from ppma13.dal12v.mail.ibm.com (dd.9e.1632.ip4.static.sl-reverse.com [50.22.158.221]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4efqjq0wa7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 01 Jun 2026 13:33:40 +0000 (GMT) Received: from pps.filterd (ppma13.dal12v.mail.ibm.com [127.0.0.1]) by ppma13.dal12v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 651DQYjf015296; Mon, 1 Jun 2026 13:33:39 GMT Received: from smtprelay05.dal12v.mail.ibm.com ([172.16.1.7]) by ppma13.dal12v.mail.ibm.com (PPS) with ESMTPS id 4egcege359-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 01 Jun 2026 13:33:39 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (smtpav03.wdc07v.mail.ibm.com [10.39.53.230]) by smtprelay05.dal12v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 651DXctM15073832 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 1 Jun 2026 13:33:38 GMT Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 838545805A; Mon, 1 Jun 2026 13:33:38 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CE21358054; Mon, 1 Jun 2026 13:33:35 +0000 (GMT) Received: from smtpclient.apple (unknown [9.61.252.116]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTPS; Mon, 1 Jun 2026 13:33:35 +0000 (GMT) Content-Type: text/plain; charset=utf-8 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.300.41.1.7\)) Subject: Re: [linux-next20260529] kernel BUG at kernel/sched/core.c:7512! From: Venkat In-Reply-To: <2f8c3d75-de2c-48bf-bd05-46b816d55c69@linux.ibm.com> Date: Mon, 1 Jun 2026 19:03:22 +0530 Cc: Madhavan Srinivasan , Mukesh Kumar Chaurasiya , Ritesh Harjani , linuxppc-dev , LKML , Srikar Dronamraju , Peter Zijlstra Content-Transfer-Encoding: quoted-printable Message-Id: <9DD4149E-FE5E-4181-A179-3C1F9EC28032@linux.ibm.com> References: <7904105b-9dfa-4efd-a5ef-bc0276ed255d@linux.ibm.com> <2f8c3d75-de2c-48bf-bd05-46b816d55c69@linux.ibm.com> To: Shrikanth Hegde X-Mailer: Apple Mail (2.3864.300.41.1.7) X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: HDMy3IfnoX8iH-oSaRpZ4uaaXyFeDUfQ X-Proofpoint-GUID: owI-U_2xM-osQByKMQVzJLSBBzcD9xwc X-Authority-Analysis: v=2.4 cv=bcVbluPB c=1 sm=1 tr=0 ts=6a1d8a35 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=LnWLKx5GKJuRwwHKcggA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjAxMDEzMSBTYWx0ZWRfX9sqcD1l5e8vo pPsjENgx5o6eiveq8wJX0P6LLk6iILj76Cflp5zMFmLI5kZTgrw7OYzaZsc8jrfCGH5oKVj4NRu 5i/EuxjPFTpkX2+mbKngsRgLj0EErtLN/pWTB3udzeaJpHdbMJT7+E1oTPI5sjpGVz5zUeVLNbd mUXw1MXit0ZMEn2jnFz2tjXZdxzgVRcHPJlJlVGpXaDVBk86GiYzFAFtuv9LuB1Ulx0nCzu2D/e 5DZn9IETgm7HAcOTPZ0WjgQtV2t4TRYlUwVEOPQMzKgvD7jXHGkYN9/ueXvGwOvvnr0s+WBA1Vz mZMQte90FGb9Comy7gRR/EVhHYu66P9jc5AMD5WTtFfAdC+MxRYru41fawajzruQ8ZfK6hpJmSK Hd41CXvb7c4Ss9IZDGKWgAAD95VHTqzUe/O8XykCeVw97oEP7j9DxcsPtZr/WyLuMzrVFDpyupV OYjiafSG1G4WjCuvJ3w== 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=2026-06-01_03,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 adultscore=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606010131 > On 1 Jun 2026, at 2:46=E2=80=AFPM, Shrikanth Hegde = wrote: >=20 > Hi Venkat. Thanks for the report. >=20 > + mukesh, ritesh >=20 > On 6/1/26 12:11 PM, Venkat Rao Bagalkote wrote: >> Greetings!!! >> I hit a kernel BUG on a linux-next kernel running on ppc64le (Power11 = LPAR). The issue was observed once in CI (Avocado tests) and I haven=E2=80= =99t been able to reproduce it reliably yet. >=20 > Can you run with lockdep and see if you can hit it? I did run with lockdep, I didn=E2=80=99t hit this issue. Though I will = try few more times, If I hit, I will respond back here. Meanwhile, I hit another boot warning with lockdep enabled, which is = reproted here [1]. [1]: = https://lore.kernel.org/all/b44aefc5-e066-478b-8d34-50d2d0deab6b@linux.ibm= .com/ Regards, Venkat. >=20 >> Architecture: ppc64le (Power11, pSeries) >> Kernel: 7.1.0-rc5-next-20260529 >> Config: PREEMPT(lazy) >> CPUs: large system (NR_CPUS=3D8192) >=20 > This is with GENERIC_ENTRY. >=20 >> So far, I have not reproduced the crash, but I am trying to stress = similar conditions using: >> parallel read workloads (fio / dd) >> memory pressure >> Traces: >> (5/8) /home/upstreamci/avocado-fvt-wrapper/tests/avocado-misc-tests/ = cpu/ppc64_cpu_test.py:PPC64Test.test_smt_loop;run-run_type- = upstream-9cfe: STARTED >> [ 1885.176400] crash hp: kexec_trylock() failed, kdump image may be = inaccurate >> [ 1885.296164] crash hp: kexec_trylock() failed, kdump image may be = inaccurate >> [ 1885.386120] crash hp: kexec_trylock() failed, kdump image may be = inaccurate >> [ 1885.556134] crash hp: kexec_trylock() failed, kdump image may be = inaccurate >> [ 1886.576119] crash hp: kexec_trylock() failed, kdump image may be = inaccurate >> [ 1886.806060] crash hp: kexec_trylock() failed, kdump image may be = inaccurate >> [ 1887.026051] crash hp: kexec_trylock() failed, kdump image may be = inaccurate >> [ 1887.456075] ------------[ cut here ]------------ >> [ 1887.456101] kernel BUG at kernel/sched/core.c:7512! >> [ 1887.456107] Oops: Exception in kernel mode, sig: 5 [#1] >> [ 1887.456111] LE PAGE_SIZE=3D4K MMU=3DRadix SMP NR_CPUS=3D8192 NUMA = pSeries >> [ 1887.456116] Modules linked in: nft_fib_inet nft_fib_ipv4 = nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 = nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 = nf_defrag_ipv4 bonding tls ip_set rfkill nf_tables fsdev_dax kmem = device_dax pseries_rng vmx_crypto dax_pmem fuse ext4 crc16 mbcache jbd2 = sd_mod nd_pmem papr_scm sg libnvdimm ibmvscsi ibmveth scsi_transport_srp = pseries_wdt >> [ 1887.456173] CPU: 28 UID: 0 PID: 85305 Comm: kexec Not tainted = 7.1.0- rc5-next-20260529 #1 PREEMPT(lazy) >> [ 1887.456180] Hardware name: IBM,9080-HEX Power11 (architected) = 0x820200 0xf000007 of:IBM,FW1110.01 (NH1110_069) hv:phyp pSeries >> [ 1887.456185] NIP: c0000000013a8e8c LR: c0000000003483bc CTR: = 0000000000000000 >> [ 1887.456190] REGS: c000000069f03070 TRAP: 0700 Not tainted = (7.1.0- rc5-next-20260529) >> [ 1887.456195] MSR: 8000000000029033 CR: = 24428222 XER: 0000005a >> [ 1887.456208] CFAR: c0000000003483b8 IRQMASK: 0 >> [ 1887.456208] GPR00: c0000000003483bc c000000069f03330 = c000000001a82100 c000000069f033e0 >> [ 1887.456208] GPR04: 0000000000000000 0000000000000001 = 0000000000000001 c000000006dd3b00 >> [ 1887.456208] GPR08: ffffffffffffff00 0000000000000001 = 0000000000000000 0000000024428220 >> [ 1887.456208] GPR12: 0000000000000300 c000000effdbef00 = 0000000000000000 0000000000000000 >> [ 1887.456208] GPR16: 0000000000000000 0000000000000000 = 0000000000000000 0000000000000000 >> [ 1887.456208] GPR20: 0000000000000000 0000000000000000 = 0000000000000000 0000000000000000 >> [ 1887.456208] GPR24: 0000000000000000 0000000000000000 = 0000000000000000 0000000000000000 >> [ 1887.456208] GPR28: 0000000000000000 0000000000000000 = 0000000000000000 c000000069f033e0 >> [ 1887.456265] NIP [c0000000013a8e8c] preempt_schedule_irq+0x44/0x118 >> [ 1887.456274] LR [c0000000003483bc] = dynamic_irqentry_exit_cond_resched+0x40/0x1a4 >> [ 1887.456282] Call Trace: >> [ 1887.456284] [c000000069f03360] [c0000000003483bc] = dynamic_irqentry_exit_cond_resched+0x40/0x1a4 >> [ 1887.456291] [c000000069f03380] [c00000000014f3bc] = do_page_fault+0xc0/0x104 >> [ 1887.456298] [c000000069f033b0] [c000000000008be0] = data_access_common_virt+0x210/0x220 >> [ 1887.456306] ---- interrupt: 300 at = __copy_tofrom_user_base+0xac/0x5a4 >> [ 1887.456313] NIP: c00000000017fc38 LR: c000000000aaa684 CTR: = 0000000000000000 >> [ 1887.456317] REGS: c000000069f033e0 TRAP: 0300 Not tainted = (7.1.0- rc5-next-20260529) >> [ 1887.456322] MSR: 8000000002009033 CR: = 24428220 XER: 2004005a >> [ 1887.456334] CFAR: c00000000017fc34 DAR: 00003fff879a8000 DSISR: = 42000000 IRQMASK: 0 >> [ 1887.456334] GPR00: 0000000000000000 c000000069f036a0 = c000000001a82100 00003fff879a8000 >> [ 1887.456334] GPR04: c0000000bb314ff0 0000000000001000 = 69f0000606480600 0200c4080368f028 >> [ 1887.456334] GPR08: 09036af00005d9c4 0600000200e80803 = 0000000000000000 0000000000000030 >> [ 1887.456334] GPR12: 0000000000000040 c000000effdbef00 = 0000000000000000 000000000000000e >> [ 1887.456334] GPR16: 0000000004a00000 000000000000001f = c000000069f038a0 c00000006e73e500 >> [ 1887.456334] GPR20: c00000006f0ff6a8 0000000000000000 = c00000006f0ff540 0000000000000001 >> [ 1887.456334] GPR24: 000000001816ce60 c0000000bb314000 = c000000002e48730 c000000069f03a30 >> [ 1887.456334] GPR28: c0000000bb314000 00003fff879a7010 = 0000000000000010 0000000000001000 >> [ 1887.456393] NIP [c00000000017fc38] = __copy_tofrom_user_base+0xac/0x5a4 >> [ 1887.456399] LR [c000000000aaa684] raw_copy_to_user+0x12c/0x314 >> [ 1887.456405] ---- interrupt: 300 >> [ 1887.456408] [c000000069f036a0] [c000000000aaa5f4] = raw_copy_to_user+0x9c/0x314 (unreliable) >> [ 1887.456416] [c000000069f036e0] [c000000000aacd08] = _copy_to_iter+0xe4/0x79c >> [ 1887.456423] [c000000069f037a0] [c000000000ab01ec] = copy_page_to_iter+0xd4/0x1a4 >> [ 1887.456429] [c000000069f037f0] [c0000000005ddc34] = filemap_read+0x420/0x4f0 >> [ 1887.456436] [c000000069f039c0] [c0080000043443e0] = ext4_file_read_iter+0x78/0x31c [ext4] >> [ 1887.456517] [c000000069f03a10] [c000000000796498] = vfs_read+0x2a8/0x3c8 >> [ 1887.456524] [c000000069f03ac0] [c00000000079726c] = ksys_read+0x88/0x140 >> [ 1887.456530] [c000000069f03b10] [c000000000032f98] = system_call_exception+0x198/0x4e0 >> [ 1887.456537] [c000000069f03e30] [c00000000000d05c] = system_call_vectored_common+0x15c/0x2ec >> [ 1887.456544] ---- interrupt: 3000 at 0x3fff9b133cf4 >> [ 1887.456549] NIP: 00003fff9b133cf4 LR: 00003fff9b133cf4 CTR: = 0000000000000000 >> [ 1887.456554] REGS: c000000069f03e60 TRAP: 3000 Not tainted = (7.1.0- rc5-next-20260529) >> [ 1887.456558] MSR: 800000000000f033 = CR: 44424402 XER: 00000000 >> [ 1887.456572] IRQMASK: 0 >> [ 1887.456572] GPR00: 0000000000000003 00003fffe5fb4190 = 0000000105087f00 0000000000000003 >> [ 1887.456572] GPR04: 00003fff82e93010 000000001816ce60 = 0000000000000022 0000000000000000 >> [ 1887.456572] GPR08: 0000000000000000 0000000000000000 = 0000000000000000 0000000000000000 >> [ 1887.456572] GPR12: 0000000000000000 00003fff9b4cd860 = 000000010507f588 0000000000000000 >> [ 1887.456572] GPR16: ffffffffffffffff 0000000000000000 = 0000000000000006 0000000000000000 >> [ 1887.456572] GPR20: 0000000000000001 00003fff9b23039c = 00003fff9b2303a0 00003fffe5fb5ee7 >> [ 1887.456572] GPR24: 0000000000000000 0000000000000000 = 00003fffe5fb5ee7 00003fffe5fb42d0 >> [ 1887.456572] GPR28: 0000000000000003 00003fff82e93010 = 000000001816ce60 0000000000000000 >> [ 1887.456626] NIP [00003fff9b133cf4] 0x3fff9b133cf4 >> [ 1887.456630] LR [00003fff9b133cf4] 0x3fff9b133cf4 >> [ 1887.456634] ---- interrupt: 3000 >> [ 1887.456637] Code: fbe1fff8 e92d0128 f8010010 f821ffd1 81490000 = 39200001 2c0a0000 40820014 892d0152 552907fe 7d290034 5529d97e = <0b090000> 60000000 3bc00000 ebed0128 >> [ 1887.456657] ---[ end trace 0000000000000000 ]--- >> If you happen to fix this, please add below tag. >> Reported-by: Venkat Rao Bagalkote >=20 > Ritesh, Mukesh, Is below possible scenario? >=20 > do_page_fault seems to enable irq's in the interrupt handler? > is that expected? if so, one might see >=20 > -- do_page_fault (enter kernel mode) > -- enables interrupts > -- gets interrupt - Sets need_resched. > -- irqentry_exit - Sees it is kernel mode. Just checks preempt = count > and calls preempt_schedule_irq, which catches both > preempt_count and !irqs_disabled. Hence the panic? >=20 > Should do_page_fault do preempt_disable when it enables the = interrupts?