Happens on tons of machines, but rather erratically to reproduce it seems. Example backtrace: [ 400.019129] ------------[ cut here ]------------ [ 400.019183] WARNING: CPU: 0 PID: 6932 at drivers/gpu/drm/i915/intel_uncore.c:649 __unclaimed_reg_debug+0x7e/0x90 [i915]() [ 400.019184] Unclaimed register detected before writing to register 0x45110 [ 400.019185] Modules linked in: snd_hda_intel i915 snd_hda_codec_hdmi x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul snd_hda_codec_realtek ghash_clmulni_intel snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core mei_me i2c_hid snd_pcm mei i2c_designware_platform lpc_ich i2c_designware_core r8169 mii sdhci_acpi sdhci mmc_core [last unloaded: i915] [ 400.019198] CPU: 0 PID: 6932 Comm: kms_flip Tainted: G U W 4.5.0-rc6-gfxbench+ #1 [ 400.019199] Hardware name: GIGABYTE M4HM87P-00/M4HM87P-00, BIOS F6 12/10/2014 [ 400.019200] 0000000000000000 ffff880036ed3910 ffffffff813fba95 ffff880036ed3958 [ 400.019202] ffffffffa039dd08 ffff880036ed3948 ffffffff81078711 0000000000045110 [ 400.019204] 0000000000000001 0000000000000000 000000000892d200 0000000000000296 [ 400.019206] Call Trace: [ 400.019209] [<ffffffff813fba95>] dump_stack+0x67/0x92 [ 400.019212] [<ffffffff81078711>] warn_slowpath_common+0x81/0xc0 [ 400.019213] [<ffffffff81078797>] warn_slowpath_fmt+0x47/0x50 [ 400.019224] [<ffffffffa030401e>] __unclaimed_reg_debug+0x7e/0x90 [i915] [ 400.019234] [<ffffffffa030b9fb>] hsw_write32+0x21b/0x270 [i915] [ 400.019242] [<ffffffffa02b4b18>] _ilk_disable_lp_wm+0x98/0xd0 [i915] [ 400.019250] [<ffffffffa02ba184>] ilk_program_watermarks+0x4e4/0x9a0 [i915] [ 400.019258] [<ffffffffa02ba750>] ilk_optimize_watermarks+0x110/0x130 [i915] [ 400.019269] [<ffffffffa032a074>] intel_atomic_commit+0x8b4/0x1610 [i915] [ 400.019272] [<ffffffff8152b9aa>] ? drm_atomic_set_crtc_for_connector+0x2a/0xe0 [ 400.019273] [<ffffffff8152c682>] drm_atomic_commit+0x32/0x50 [ 400.019275] [<ffffffff815090d5>] drm_atomic_helper_set_config+0x75/0xb0 [ 400.019277] [<ffffffff8151cac0>] drm_mode_set_config_internal+0x60/0x110 [ 400.019279] [<ffffffff815201d6>] drm_mode_setcrtc+0x186/0x4f0 [ 400.019280] [<ffffffff8118d0b8>] ? __might_fault+0x48/0xa0 [ 400.019282] [<ffffffff815120bd>] drm_ioctl+0x13d/0x590 [ 400.019283] [<ffffffff81520050>] ? drm_mode_setplane+0x1b0/0x1b0 [ 400.019285] [<ffffffff811e5c7a>] do_vfs_ioctl+0x8a/0x670 [ 400.019287] [<ffffffff81197b6a>] ? vm_munmap+0x4a/0x60 [ 400.019289] [<ffffffff811f1b2a>] ? __fget_light+0x6a/0x90 [ 400.019290] [<ffffffff811e629c>] SyS_ioctl+0x3c/0x70 [ 400.019292] [<ffffffff817c2e1b>] entry_SYSCALL_64_fastpath+0x16/0x73 [ 400.019293] ---[ end trace 98c87d6dfcaa0a14 ]--- I've seen it on all ilk-style machines.
*** This bug has been marked as a duplicate of bug 94349 ***
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