FYI, we noticed the following commit: commit: 5c0338c68706be53b3dc472e4308961c36e4ece1 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master in testcase: blogbench with following parameters: disk: 1SSD fs: btrfs cpufreq_governor: performance test-description: Blogbench is a portable filesystem benchmark that tries to reproduce the load of a real-world busy file server. test-url: https://www.pureftpd.org/project/blogbench on test machine: 16 threads Intel(R) Xeon(R) CPU D-1541 @ 2.10GHz with 8G memory caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +---------------------------------------------------------------------------+------------+------------+ | | 74cbd96bc2 | 5c0338c687 | +---------------------------------------------------------------------------+------------+------------+ | boot_successes | 50 | 3 | | boot_failures | 22 | | | WARNING:at_drivers/gpu/drm/i915/intel_display.c:#intel_modeset_init[i915] | 2 | | | INFO:creating/lkp/benchmarks/ltp/output_directory | 12 | | | INFO:creating/lkp/benchmarks/ltp/results_directory | 12 | | | INFO:ltp-pan_reported_all_tests_PASS | 10 | | | WARNING:at_arch/x86/events/intel/core.c:#intel_pmu_handle_irq | 2 | | | invoked_oom-killer:gfp_mask=0x | 1 | | | Mem-Info | 1 | | | Out_of_memory:Kill_process | 1 | | | BUG:kernel_reboot-without-warning_in_test_stage | 5 | | | BUG:kernel_in_stage | 1 | | +---------------------------------------------------------------------------+------------+------------+ kern :warn : [ 77.570232] WARNING: CPU: 11 PID: 398 at kernel/workqueue.c:4132 workqueue_set_max_active+0x77/0x80 kern :warn : [ 77.581262] Modules linked in: dm_mod rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver btrfs xor raid6_pq sd_mod intel_rapl sg sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel ast kvm ttm irqbypass crct10dif_pclmul drm_kms_helper crc32_pclmul syscopyarea crc32c_intel ahci sysfillrect ghash_clmulni_intel sysimgblt snd_pcm libahci fb_sys_fops snd_timer pcbc snd drm aesni_intel ipmi_si crypto_simd soundcore ipmi_devintf glue_helper mxm_wmi cryptd pcspkr intel_pch_thermal libata shpchp ipmi_msghandler wmi acpi_pad ip_tables kern :warn : [ 77.631678] CPU: 11 PID: 398 Comm: kworker/u32:3 Not tainted 4.13.0-rc1-00060-g5c0338c #2 kern :warn : [ 77.640506] Hardware name: Supermicro SYS-5018D-FN4T/X10SDV-8C-TLN4F, BIOS 1.1 03/02/2016 kern :warn : [ 77.649399] Workqueue: btrfs-delayed-meta btrfs_delayed_meta_helper [btrfs] kern :warn : [ 77.657032] task: ffff88022caa2640 task.stack: ffffc90001d38000 kern :warn : [ 77.663585] RIP: 0010:workqueue_set_max_active+0x77/0x80 kern :warn : [ 77.669547] RSP: 0018:ffffc90001d3be08 EFLAGS: 00010206 kern :warn : [ 77.675458] RAX: 0000000000000002 RBX: ffff880270914f78 RCX: 0000000000000001 kern :warn : [ 77.683294] RDX: 0000000000000002 RSI: 000000000002000e RDI: ffff88027a89fc00 kern :warn : [ 77.691093] RBP: ffffc90001d3be48 R08: 0000000000000040 R09: 0000000180200010 kern :warn : [ 77.698882] R10: ffffc90001d3bd08 R11: 0000000000001000 R12: ffff880259181810 kern :warn : [ 77.706682] R13: ffff880270914f40 R14: ffff880259181828 R15: 0000000000000000 kern :warn : [ 77.714482] FS: 0000000000000000(0000) GS:ffff88025b6c0000(0000) knlGS:0000000000000000 kern :warn : [ 77.723262] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 kern :warn : [ 77.729666] CR2: 00007f5188d2ef28 CR3: 0000000270aaf000 CR4: 00000000003406e0 kern :warn : [ 77.737500] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 kern :warn : [ 77.745341] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 kern :warn : [ 77.753212] Call Trace: kern :warn : [ 77.756391] ? btrfs_scrubparity_helper+0x1a2/0x330 [btrfs] kern :warn : [ 77.762635] ? pwq_activate_delayed_work+0x41/0xb0 kern :warn : [ 77.768107] btrfs_delayed_meta_helper+0xe/0x10 [btrfs] kern :warn : [ 77.774041] process_one_work+0x198/0x3e0 kern :warn : [ 77.778740] worker_thread+0x4e/0x3e0 kern :warn : [ 77.783124] kthread+0x114/0x150 kern :warn : [ 77.787050] ? process_one_work+0x3e0/0x3e0 kern :warn : [ 77.791927] ? kthread_create_on_node+0x40/0x40 kern :warn : [ 77.797180] ret_from_fork+0x25/0x30 kern :warn : [ 77.801444] Code: c4 48 8d 58 90 74 15 48 89 df e8 95 d6 ff ff 48 8b 43 70 49 39 c4 48 8d 58 90 75 eb 4c 89 ef e8 b0 1d 93 00 5b 41 5c 41 5d 5d c3 <0f> ff c3 66 0f 1f 44 00 00 0f 1f 44 00 00 55 48 89 d0 48 c7 c6 kern :warn : [ 77.821783] ---[ end trace c183e3c1416ebbe5 ]--- To reproduce: git clone https://github.com/01org/lkp-tests.git cd lkp-tests bin/lkp install job.yaml # job file is attached in this email bin/lkp run job.yaml Thanks, Kernel Test Robot