Haven't figured out the steps to reproduce but the thing that happens (seems random) is that my window manager (XFCE 4.12) starts responding slowly especially when switching windows with Alt+Tab and eventually crawls to a stop (when I notice it happening I can usually bring it to a crawl in about 4-5 seconds of intensive alt+tabbing). From then on, only SSH to the laptop works. It is my feeling that this issue started somewhere around kernel 4.0.2... My cmdline is: BOOT_IMAGE=/boot/vmlinuz-linux root=UUID=44cf687d-4827-4765-8758-98d44a745d07 rw quiet resume=/dev/sda2 i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1 i915.modeset=1 elevator=noop nmi_watchdog=0 init=/usr/lib/systemd/systemd After hanging, dmesg contains many entries of the following types: 1. [ 288.920149] ------------[ cut here ]------------ [ 288.920217] WARNING: CPU: 0 PID: 431 at drivers/gpu/drm/drm_irq.c:1137 drm_wait_one_vblank+0x16a/0x1d0 [drm]() [ 288.920222] vblank wait timed out on crtc 0 [ 288.920225] Modules linked in: fuse ctr ccm joydev mousedev snd_hda_codec_hdmi snd_hda_codec_conexant snd_hda_codec_generic intel_rapl iosf_mbi x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel arc4 ip6t_REJECT nf_reject_ipv6 kvm iwldvm xt_hl ip6t_rt mac80211 crct10dif_pclmul crc32_pclmul iTCO_wdt iTCO_vendor_support crc32c_intel ghash_clmulni_intel aesni_intel nf_conntrack_ipv6 nf_defrag_ipv6 aes_x86_64 lrw gf128mul glue_helper snd_hda_intel ipt_REJECT snd_hda_controller ablk_helper nf_reject_ipv4 iwlwifi psmouse snd_hda_codec cryptd snd_hwdep serio_raw snd_pcm xt_limit cfg80211 snd_timer thinkpad_acpi xt_tcpudp thermal nvram ac tpm_tis snd tpm rfkill xt_addrtype battery e1000e evdev soundcore mac_hid i2c_i801 ptp mei_me pps_core mei shpchp lpc_ich nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack [ 288.920318] processor wmi ip6table_filter ip6_tables nf_conntrack_netbios_ns nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack iptable_filter ip_tables x_tables sch_fq_codel usbnet mii tp_smapi(O) thinkpad_ec(O) nfs lockd grace sunrpc fscache cpufreq_powersave acpi_call(O) ext4 crc16 mbcache jbd2 sd_mod atkbd libps2 ahci libahci libata sdhci_pci ehci_pci sdhci led_class ehci_hcd scsi_mod mmc_core usbcore usb_common i8042 serio i915 button intel_gtt i2c_algo_bit video drm_kms_helper drm i2c_core [ 288.920384] CPU: 0 PID: 431 Comm: Xorg Tainted: G O 4.0.4-2-ARCH #1 [ 288.920388] Hardware name: LENOVO 4177CTO/4177CTO, BIOS 83ET70WW (1.40 ) 06/12/2012 [ 288.920392] 0000000000000000 0000000095afcab9 ffff8800d104f9f8 ffffffff81574b23 [ 288.920399] 0000000000000000 ffff8800d104fa50 ffff8800d104fa38 ffffffff81074dda [ 288.920405] 00000000000011ce ffff880213409800 0000000000000000 0000000000000000 [ 288.920412] Call Trace: [ 288.920425] [<ffffffff81574b23>] dump_stack+0x4c/0x6e [ 288.920436] [<ffffffff81074dda>] warn_slowpath_common+0x8a/0xc0 [ 288.920444] [<ffffffff81074e65>] warn_slowpath_fmt+0x55/0x70 [ 288.920455] [<ffffffff810dede0>] ? migrate_timer_list+0xd0/0xd0 [ 288.920473] [<ffffffff810b6799>] ? finish_wait+0x59/0x70 [ 288.920499] [<ffffffffa001e14a>] drm_wait_one_vblank+0x16a/0x1d0 [drm] [ 288.920505] [<ffffffff810b6c70>] ? wake_atomic_t_function+0x60/0x60 [ 288.920535] [<ffffffffa001e1d0>] drm_crtc_wait_one_vblank+0x20/0x30 [drm] [ 288.920564] [<ffffffffa0080958>] drm_plane_helper_commit+0x298/0x300 [drm_kms_helper] [ 288.920588] [<ffffffffa0080a5a>] drm_plane_helper_update+0x9a/0xf0 [drm_kms_helper] [ 288.920630] [<ffffffffa013e106>] intel_crtc_set_config+0xdb6/0x1010 [i915] [ 288.920665] [<ffffffffa0026796>] drm_mode_set_config_internal+0x66/0x100 [drm] [ 288.920694] [<ffffffffa002b206>] drm_mode_setcrtc+0x366/0x5c0 [drm] [ 288.920726] [<ffffffffa001bcab>] drm_ioctl+0x1db/0x640 [drm] [ 288.920752] [<ffffffffa002aea0>] ? drm_mode_setplane+0x250/0x250 [drm] [ 288.920762] [<ffffffff811ebbf6>] do_vfs_ioctl+0x2c6/0x4d0 [ 288.920771] [<ffffffff811dac85>] ? __sb_end_write+0x35/0x70 [ 288.920779] [<ffffffff811f6432>] ? __fget+0x72/0xb0 [ 288.920785] [<ffffffff811ebe81>] SyS_ioctl+0x81/0xa0 [ 288.920794] [<ffffffff8157a449>] system_call_fastpath+0x12/0x17 [ 288.920799] ---[ end trace 30502e08f296676c ]--- [ 289.043572] ------------[ cut here ]------------ and 2. [ 289.043572] ------------[ cut here ]------------ [ 289.043639] WARNING: CPU: 0 PID: 431 at drivers/gpu/drm/drm_irq.c:1137 drm_wait_one_vblank+0x16a/0x1d0 [drm]() [ 289.043644] vblank wait timed out on crtc 0 [ 289.043646] Modules linked in: fuse ctr ccm joydev mousedev snd_hda_codec_hdmi snd_hda_codec_conexant snd_hda_codec_generic intel_rapl iosf_mbi x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel arc4 ip6t_REJECT nf_reject_ipv6 kvm iwldvm xt_hl ip6t_rt mac80211 crct10dif_pclmul crc32_pclmul iTCO_wdt iTCO_vendor_support crc32c_intel ghash_clmulni_intel aesni_intel nf_conntrack_ipv6 nf_defrag_ipv6 aes_x86_64 lrw gf128mul glue_helper snd_hda_intel ipt_REJECT snd_hda_controller ablk_helper nf_reject_ipv4 iwlwifi psmouse snd_hda_codec cryptd snd_hwdep serio_raw snd_pcm xt_limit cfg80211 snd_timer thinkpad_acpi xt_tcpudp thermal nvram ac tpm_tis snd tpm rfkill xt_addrtype battery e1000e evdev soundcore mac_hid i2c_i801 ptp mei_me pps_core mei shpchp lpc_ich nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack [ 289.043726] processor wmi ip6table_filter ip6_tables nf_conntrack_netbios_ns nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack iptable_filter ip_tables x_tables sch_fq_codel usbnet mii tp_smapi(O) thinkpad_ec(O) nfs lockd grace sunrpc fscache cpufreq_powersave acpi_call(O) ext4 crc16 mbcache jbd2 sd_mod atkbd libps2 ahci libahci libata sdhci_pci ehci_pci sdhci led_class ehci_hcd scsi_mod mmc_core usbcore usb_common i8042 serio i915 button intel_gtt i2c_algo_bit video drm_kms_helper drm i2c_core [ 289.043785] CPU: 0 PID: 431 Comm: Xorg Tainted: G W O 4.0.4-2-ARCH #1 [ 289.043789] Hardware name: LENOVO 4177CTO/4177CTO, BIOS 83ET70WW (1.40 ) 06/12/2012 [ 289.043793] 0000000000000000 0000000095afcab9 ffff8800d104fa08 ffffffff81574b23 [ 289.043799] 0000000000000000 ffff8800d104fa60 ffff8800d104fa48 ffffffff81074dda [ 289.043804] 00000000000011d5 ffff880213409800 0000000000000000 0000000000000000 [ 289.043811] Call Trace: [ 289.043824] [<ffffffff81574b23>] dump_stack+0x4c/0x6e [ 289.043835] [<ffffffff81074dda>] warn_slowpath_common+0x8a/0xc0 [ 289.043842] [<ffffffff81074e65>] warn_slowpath_fmt+0x55/0x70 [ 289.043853] [<ffffffff810dede0>] ? migrate_timer_list+0xd0/0xd0 [ 289.043869] [<ffffffff810b6799>] ? finish_wait+0x59/0x70 [ 289.043892] [<ffffffffa001e14a>] drm_wait_one_vblank+0x16a/0x1d0 [drm] [ 289.043898] [<ffffffff810b6c70>] ? wake_atomic_t_function+0x60/0x60 [ 289.043925] [<ffffffffa001e1d0>] drm_crtc_wait_one_vblank+0x20/0x30 [drm] [ 289.043950] [<ffffffffa0080958>] drm_plane_helper_commit+0x298/0x300 [drm_kms_helper] [ 289.043975] [<ffffffffa0080a5a>] drm_plane_helper_update+0x9a/0xf0 [drm_kms_helper] [ 289.044003] [<ffffffffa0027699>] __setplane_internal+0x259/0x2a0 [drm] [ 289.044028] [<ffffffffa002787e>] drm_mode_cursor_common+0x19e/0x3c0 [drm] [ 289.044037] [<ffffffff814584f0>] ? sock_read_iter+0xf0/0xf0 [ 289.044065] [<ffffffffa002b4b0>] drm_mode_cursor_ioctl+0x50/0x70 [drm] [ 289.044084] [<ffffffffa001bcab>] drm_ioctl+0x1db/0x640 [drm] [ 289.044105] [<ffffffffa002b460>] ? drm_mode_setcrtc+0x5c0/0x5c0 [drm] [ 289.044114] [<ffffffff811d955d>] ? do_readv_writev+0x1dd/0x300 [ 289.044121] [<ffffffff814584f0>] ? sock_read_iter+0xf0/0xf0 [ 289.044127] [<ffffffff811d7b30>] ? new_sync_read+0xd0/0xd0 [ 289.044133] [<ffffffff811ebbf6>] do_vfs_ioctl+0x2c6/0x4d0 [ 289.044141] [<ffffffff811f6432>] ? __fget+0x72/0xb0 [ 289.044146] [<ffffffff811ebe81>] SyS_ioctl+0x81/0xa0 [ 289.044153] [<ffffffff8157a449>] system_call_fastpath+0x12/0x17 [ 289.044158] ---[ end trace 30502e08f296676d ]---
We seem to have neglected this bug. Apologies. If the problem persists with latest kernels, please file a bug at the freedesktop.org bugzilla [1], referencing this bug. Thank you. [1] https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel