Hello, kernel test robot noticed "BUG:kernel_NULL_pointer_dereference,address" on: commit: 5df2998b7baa3fd4cb66272d1ea5625573b4a63f ("[PATCH 3/3] group_cpus: optimize grp_spread_init_one()") url: https://github.com/intel-lab-lkp/linux/commits/Yury-Norov/bitmap-cpumask-introduce-and_andnot-search-helper-and-iterator/20250911-051023 base: https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git 8ad25ebfa70e86860559b306bbc923c7db4fcac6 patch link: https://lore.kernel.org/all/20250910210850.404834-4-yury.norov@gmail.com/ patch subject: [PATCH 3/3] group_cpus: optimize grp_spread_init_one() in testcase: stress-ng version: stress-ng-x86_64-665b4465f-1_20250912 with following parameters: nr_threads: 100% testtime: 60s test: cpu-online cpufreq_governor: performance config: x86_64-rhel-9.4 compiler: gcc-14 test machine: 104 threads 2 sockets (Skylake) with 192G memory (please refer to attached dmesg/kmsg for entire log/backtrace) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot | Closes: https://lore.kernel.org/oe-lkp/202509192101.5d4e0282-lkp@intel.com The kernel config and materials to reproduce are available at: https://download.01.org/0day-ci/archive/20250919/202509192101.5d4e0282-lkp@intel.com [1] we observed the issue happens randomly in our tests. ========================================================================================= tbox_group/testcase/rootfs/kconfig/compiler/nr_threads/testtime/test/cpufreq_governor: lkp-skl-fpga01/stress-ng/debian-13-x86_64-20250902.cgz/x86_64-rhel-9.4/gcc-14/100%/60s/cpu-online/performance commit: 6ade57f62d272 ("group_cpus: don't call cpumask_weight() prematurely") 5df2998b7baa3 ("group_cpus: optimize grp_spread_init_one()") 6ade57f62d272d3e 5df2998b7baa3fd4cb66272d1ea ---------------- --------------------------- fail:runs %reproduction fail:runs | | | :30 43% 13:30 dmesg.BUG:kernel_NULL_pointer_dereference,address :30 43% 13:30 dmesg.Kernel_panic-not_syncing:Fatal_exception :30 43% 13:30 dmesg.Oops :30 43% 13:30 dmesg.RIP:blk_mq_all_tag_iter and sorry our bot failed to upload correct dmesg in above link [1] attached one FYI. [ 43.544050][ T130] BUG: kernel NULL pointer dereference, address: 0000000000000004 [ 43.552056][ T130] #PF: supervisor read access in kernel mode [ 43.558218][ T130] #PF: error_code(0x0000) - not-present page [ 43.564340][ T130] PGD 0 P4D 0 [ 43.567866][ T130] Oops: Oops: 0000 [#1] SMP PTI [ 43.572855][ T130] CPU: 19 UID: 0 PID: 130 Comm: cpuhp/19 Not tainted 6.17.0-rc1-00014-g5df2998b7baa #1 VOLUNTARY [ 43.583575][ T130] Hardware name: Intel Corporation S2600BT/S2600BT, BIOS SE5C620.86B.1D.01.0147.121320181755 12/13/2018 [ 43.594817][ T130] RIP: 0010:blk_mq_all_tag_iter+0x1a/0x230 [ 43.600779][ T130] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 0f 1f 44 00 00 41 57 41 56 41 55 41 54 49 89 fc 55 53 48 83 ec 50 <8b> 4f 04 48 89 34 24 48 89 54 24 08 65 48 8b 05 8a b4 48 02 48 89 [ 43.620822][ T130] RSP: 0018:ffffc9000ce5fda0 EFLAGS: 00010286 [ 43.627048][ T130] RAX: 0000604fe9627758 RBX: ffffc9000ce5fe28 RCX: 0000000000000068 [ 43.635176][ T130] RDX: ffffc9000ce5fe28 RSI: ffffffff8199e310 RDI: 0000000000000000 [ 43.643294][ T130] RBP: ffff88810dd98600 R08: ffffffff833d72a0 R09: ffff8881003c8710 [ 43.651410][ T130] R10: ffffc9000ce5fdb0 R11: ffffc9000ce5fdb8 R12: 0000000000000000 [ 43.659516][ T130] R13: 0000000000000013 R14: ffff88810dd98760 R15: ffff8897e08dbde8 [ 43.667621][ T130] FS: 0000000000000000(0000) GS:ffff88985caa3000(0000) knlGS:0000000000000000 [ 43.676681][ T130] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 43.683393][ T130] CR2: 0000000000000004 CR3: 000000303de24004 CR4: 00000000007726f0 [ 43.691491][ T130] PKRU: 55555554 [ 43.695175][ T130] Call Trace: [ 43.698593][ T130] [ 43.701657][ T130] ? __call_rcu_common+0xb0/0x2f0 [ 43.707850][ T130] ? xas_load+0xd/0xf0 [ 43.712054][ T130] ? xa_load+0x58/0xb0 [ 43.716259][ T130] blk_mq_hctx_notify_offline+0xd1/0x170 [ 43.722025][ T130] ? __pfx_blk_mq_hctx_notify_offline+0x10/0x10 [ 43.728390][ T130] cpuhp_invoke_callback+0x1c7/0x370 [ 43.733805][ T130] ? __pfx_smpboot_thread_fn+0x10/0x10 [ 43.739386][ T130] cpuhp_thread_fun+0x98/0x170 [ 43.744273][ T130] smpboot_thread_fn+0xc8/0x1b0 [ 43.749254][ T130] kthread+0xe5/0x1f0 [ 43.753363][ T130] ? __pfx_kthread+0x10/0x10 [ 43.758082][ T130] ret_from_fork+0x132/0x170 [ 43.762799][ T130] ? __pfx_kthread+0x10/0x10 [ 43.767513][ T130] ret_from_fork_asm+0x1a/0x30 [ 43.772398][ T130] [ 43.775532][ T130] Modules linked in: intel_rapl_msr intel_rapl_common intel_uncore_frequency intel_uncore_frequency_common btrfs blake2b_generic xor raid6_pq skx_edac skx_edac_common nfit libnvdimm sd_mod sg x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel irdma kvm irqbypass ice snd_pcm ghash_clmulni_intel ahci snd_timer rapl gnss snd ast ib_uverbs nvme intel_cstate libahci ipmi_ssif drm_client_lib soundcore binfmt_misc acpi_power_meter mei_me drm_shmem_helper i2c_i801 ib_core ioatdma pcspkr nvme_core libata ipmi_si intel_uncore acpi_ipmi drm_kms_helper mei i2c_smbus intel_pch_thermal lpc_ich dca wmi ipmi_devintf ipmi_msghandler acpi_pad joydev drm fuse nfnetlink [ 43.836729][ T130] CR2: 0000000000000004 [ 43.841005][ T130] ---[ end trace 0000000000000000 ]--- [ 43.855607][ T130] pstore: backend (erst) writing error (-28) -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki