FYI, we noticed the following commit: commit: 08f018c5b051bb848488671a01dc98e7c65fa9cc ("extra underrun check") https://github.com/vsyrjala/linux.git g4x_atomic_wm_4_new in testcase: netperf with following parameters: ip: ipv4 runtime: 900s nr_threads: 25% cluster: cs-localhost test: TCP_STREAM cpufreq_governor: performance test-description: Netperf is a benchmark that can be use to measure various aspect of networking performance. test-url: http://www.netperf.org/netperf/ on test machine: 4 threads Intel(R) Core(TM) i5-3317U CPU @ 1.70GHz with 4G memory caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +---------------------------------------------------------------------------+------------+------------+ | | 1111d7058d | 08f018c5b0 | +---------------------------------------------------------------------------+------------+------------+ | boot_successes | 4 | 4 | | boot_failures | 1 | 1 | | WARNING:at_drivers/gpu/drm/i915/intel_display.c:#intel_modeset_init[i915] | 1 | 1 | | WARNING:at_drivers/gpu/drm/i915/intel_drv.h:#gen6_read32[i915] | 0 | 1 | +---------------------------------------------------------------------------+------------+------------+ [ 693.550680] WARNING: CPU: 0 PID: 41 at drivers/gpu/drm/i915/intel_drv.h:1752 gen6_read32+0x192/0x1e0 [i915] [ 693.550681] RPM wakelock ref not held during HW access [ 693.550682] Modules linked in: rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver netconsole snd_hda_codec_hdmi snd_hda_codec_conexant snd_hda_codec_generic intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel pcbc aesni_intel crypto_simd glue_helper ahci cryptd serio_raw pcspkr libahci libata snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm bcma snd_timer snd soundcore i915 drm_kms_helper syscopyarea sysfillrect uvcvideo sysimgblt fb_sys_fops videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 ideapad_laptop videobuf2_core drm shpchp sparse_keymap videodev wmi rfkill video ip_tables [ 693.550728] CPU: 0 PID: 41 Comm: kworker/0:1 Tainted: G W 4.11.0-rc4-01041-g08f018c #1 [ 693.550730] Hardware name: LENOVO IdeaPad U410 /Lenovo , BIOS 65CN15WW 06/05/2012 [ 693.550736] Workqueue: events console_callback [ 693.550737] Call Trace: [ 693.550745] dump_stack+0x63/0x8a [ 693.550750] __warn+0xcb/0xf0 [ 693.550753] warn_slowpath_fmt+0x4f/0x60 [ 693.550793] ? ilk_compute_wm_maximums+0x43/0xb0 [i915] [ 693.550838] gen6_read32+0x192/0x1e0 [i915] [ 693.550884] intel_check_cpu_fifo_underruns+0x161/0x270 [i915] [ 693.550930] intel_atomic_commit_tail+0x371/0x1000 [i915] [ 693.550935] ? __queue_work+0x178/0x4a0 [ 693.550978] ? intel_atomic_commit_ready+0x75/0x88 [i915] [ 693.551019] intel_atomic_commit+0x3b6/0x4c0 [i915] [ 693.551025] ? refcount_dec_and_test+0x11/0x20 [ 693.551049] ? drm_mode_object_put+0x49/0x80 [drm] [ 693.551071] drm_atomic_commit+0x4b/0x50 [drm] [ 693.551084] drm_atomic_helper_connector_dpms+0xef/0x180 [drm_kms_helper] [ 693.551095] drm_fb_helper_dpms+0xf6/0x130 [drm_kms_helper] [ 693.551105] drm_fb_helper_blank+0x48/0x90 [drm_kms_helper] [ 693.551146] intel_fbdev_blank+0x1a/0x70 [i915] [ 693.551150] fb_blank+0x57/0xb0 [ 693.551153] fbcon_blank+0x26c/0x330 [ 693.551156] ? update_curr+0x71/0x1d0 [ 693.551160] ? lock_timer_base+0x81/0xa0 [ 693.551163] ? try_to_del_timer_sync+0x44/0x60 [ 693.551168] do_blank_screen+0x161/0x1f0 [ 693.551172] console_callback+0x6d/0x150 [ 693.551175] ? pwq_dec_nr_in_flight+0x4d/0xa0 [ 693.551178] process_one_work+0x1a3/0x480 [ 693.551182] worker_thread+0x4e/0x4d0 [ 693.551185] kthread+0x10c/0x140 [ 693.551188] ? process_one_work+0x480/0x480 [ 693.551191] ? kthread_create_on_node+0x40/0x40 [ 693.551196] ret_from_fork+0x2c/0x40 [ 693.551200] ---[ end trace d9ac7a460b2ba520 ]--- 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, Xiaolong