Got the following trace when running igt@gem_ctx_create@basic-files on fi-snb-2520m with CI_DRM_2355: [ 99.153133] ------------[ cut here ]------------ [ 99.153193] WARNING: CPU: 1 PID: 7165 at drivers/gpu/drm/i915/intel_uncore.c:232 __gen6_gt_wait_for_fifo+0xae/0xc0 [i915] [ 99.153195] WARN_ON(loop < 0 && fifo <= 20) [ 99.153197] Modules linked in: x86_pkg_temp_thermal intel_powerclamp snd_hda_codec_hdmi coretemp snd_hda_codec_generic crct10dif_pclmul snd_hda_intel crc32_pclmul snd_hda_codec snd_hwdep snd_hda_core ghash_clmulni_intel mei_me snd_pcm mei lpc_ich i915 sdhci_pci sdhci mmc_core e1000e ptp pps_core prime_numbers [ 99.153238] CPU: 1 PID: 7165 Comm: gem_ctx_create Not tainted 4.11.0-rc2-CI-CI_DRM_2355+ #1 [ 99.153240] Hardware name: LENOVO 42962WU/42962WU, BIOS 8DET56WW (1.26 ) 12/01/2011 [ 99.153242] Call Trace: [ 99.153247] dump_stack+0x67/0x92 [ 99.153252] __warn+0xc6/0xe0 [ 99.153256] warn_slowpath_fmt+0x4a/0x50 [ 99.153279] __gen6_gt_wait_for_fifo+0xae/0xc0 [i915] [ 99.153299] gen6_write32+0x189/0x2a0 [i915] [ 99.153319] i9xx_submit_request+0x3e/0x50 [i915] [ 99.153339] submit_notify+0x3f/0x5c [i915] [ 99.153355] __i915_sw_fence_complete+0x176/0x220 [i915] [ 99.153358] ? debug_object_activate+0xe2/0x1e0 [ 99.153375] i915_sw_fence_complete+0x25/0x40 [i915] [ 99.153391] i915_sw_fence_commit+0x1c/0x30 [i915] [ 99.153410] __i915_add_request+0x238/0x540 [i915] [ 99.153430] i915_gem_do_execbuffer.isra.16+0x157e/0x1b70 [i915] [ 99.153433] ? __lock_acquire+0x45b/0x1bb0 [ 99.153437] ? __might_fault+0x3e/0x90 [ 99.153460] i915_gem_execbuffer2+0xb5/0x220 [i915] [ 99.153465] drm_ioctl+0x200/0x450 [ 99.153469] ? __slab_free+0x39f/0x4f0 [ 99.153486] ? i915_gem_execbuffer+0x330/0x330 [i915] [ 99.153492] ? putname+0x4f/0x60 [ 99.153496] do_vfs_ioctl+0x90/0x6e0 [ 99.153499] ? entry_SYSCALL_64_fastpath+0x5/0xb1 [ 99.153503] ? __this_cpu_preempt_check+0x13/0x20 [ 99.153506] ? trace_hardirqs_on_caller+0xe7/0x200 [ 99.153509] SyS_ioctl+0x3c/0x70 [ 99.153513] entry_SYSCALL_64_fastpath+0x1c/0xb1 [ 99.153516] RIP: 0033:0x7f9c60d44357 [ 99.153518] RSP: 002b:00007ffc39a15108 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 99.153521] RAX: ffffffffffffffda RBX: ffffffff8147ea93 RCX: 00007f9c60d44357 [ 99.153523] RDX: 00007ffc39a151e0 RSI: 0000000040406469 RDI: 0000000000000005 [ 99.153525] RBP: ffffc900006dbf88 R08: 0000000000000005 R09: 0000000000000000 [ 99.153526] R10: 0000000000000021 R11: 0000000000000246 R12: 0000000000000000 [ 99.153528] R13: 0000000000000005 R14: 0000000040406469 R15: 000000000000023d [ 99.153532] ? __this_cpu_preempt_check+0x13/0x20 [ 99.153537] ---[ end trace f5861f5a24c919de ]--- Raw results: https://intel-gfx-ci.01.org/CI/CI_DRM_2355/fi-snb-2520m/igt@gem_ctx_create@basic-files.html
The quickest "fix" would be to silence this WARN and just wait for the fifodbg to spot the undeflow instead.
Failure rate 1/31 run(s) (3%) Raising the priority as it is seen in CI.
Possible fix: https://patchwork.freedesktop.org/series/22571/ => https://patchwork.freedesktop.org/patch/148719/
Reference to Mika's patch: https://lists.freedesktop.org/archives/intel-gfx/2017-May/126990.html
The warn has been disabled and gt fifo overflow (reporting) is now handled in the mmio_debug path.
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