On Fri, 29 May 2015, Shuah Khan shuahkh@osg.samsung.com wrote:
I am seeing the following in the dmesg on 4.0.4 with rt patch
[ 5.720319] ------------[ cut here ]------------ [ 5.720347] WARNING: CPU: 6 PID: 466 at drivers/gpu/drm/i915/intel_display.c:9748 intel_check_page_flip+0xaa/0xf0 [i915]() [ 5.720349] WARN_ON(!in_interrupt()) [ 5.720350] Modules linked in: [ 5.720376] binfmt_misc rfcomm bnep arc4 eeepc_wmi hid_generic asus_wmi sparse_keymap iwlmvm intel_powerclamp coretemp kvm_intel kvm mac80211 crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul dm_multipath glue_helper snd_hda_codec_hdmi scsi_dh ablk_helper cryptd microcode btusb iwlwifi bluetooth serio_raw cfg80211 i915 snd_hda_codec_realtek snd_hda_codec_generic lpc_ich snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi drm_kms_helper snd_seq drm video snd_seq_device mac_hid snd_timer snd mei_me wmi mei shpchp soundcore i2c_algo_bit usbhid hid parport_pc ppdev lp parport autofs4 btrfs xor raid6_pq psmouse dm_mirror r8169 ahci dm_region_hash libahci mii dm_log [ 5.720379] CPU: 6 PID: 466 Comm: irq/32-i915 Not tainted 4.0.4-rt1+ #8 [ 5.720380] Hardware name: System76, Inc. Wild Dog Performance/H87-PLUS, BIOS 0705 12/05/2013 [ 5.720382] 0000000000000009 ffff8803ea39bc98 ffffffff817c0694 0000000000000002 [ 5.720383] ffff8803ea39bce8 ffff8803ea39bcd8 ffffffff81073d8a 0000000000000001 [ 5.720384] ffff8803eb184000 ffff8800d7804800 0000000000000000 0000000000000000 [ 5.720385] Call Trace: [ 5.720390] [<ffffffff817c0694>] dump_stack+0x4f/0x90 [ 5.720393] [<ffffffff81073d8a>] warn_slowpath_common+0x8a/0xe0 [ 5.720395] [<ffffffff81073e26>] warn_slowpath_fmt+0x46/0x50 [ 5.720410] [<ffffffffa040bdba>] intel_check_page_flip+0xaa/0xf0 [i915] [ 5.720420] [<ffffffffa03d7888>] ironlake_irq_handler+0x2e8/0x1000 [i915] [ 5.720423] [<ffffffff813e7787>] ? debug_smp_processor_id+0x17/0x20 [ 5.720424] [<ffffffff81074512>] ? pin_current_cpu+0x92/0x1d0 [ 5.720426] [<ffffffff810d0690>] ? irq_thread_fn+0x50/0x50 [ 5.720428] [<ffffffff810d06b7>] irq_forced_thread_fn+0x27/0x80 [ 5.720429] [<ffffffff810d0c4f>] irq_thread+0x10f/0x160 [ 5.720430] [<ffffffff810d0740>] ? wake_threads_waitq+0x30/0x30 [ 5.720432] [<ffffffff810d0b40>] ? irq_thread_check_affinity+0x90/0x90 [ 5.720433] [<ffffffff81093d7b>] kthread+0xbb/0xe0 [ 5.720434] [<ffffffff81093cc0>] ? kthread_worker_fn+0x1a0/0x1a0 [ 5.720436] [<ffffffff817c6bd8>] ret_from_fork+0x58/0x90 [ 5.720437] [<ffffffff81093cc0>] ? kthread_worker_fn+0x1a0/0x1a0 [ 5.720437] ---[ end trace 0000000000000002 ]---
There seem to be few past bug reports on this issue. Has this been fixed? Should I be concerned about this?
One of the old bugs [1] was about using in_irq() which didn't work for threaded irqs, hence the switch to in_interrupt(). The backtrace seems to indicate intel_check_page_flip() is being called from irq context; I do not know if the rt patchset has an impact on this.
BR, Jani.
[1] https://bugs.freedesktop.org/show_bug.cgi?id=89321
thanks, -- Shuah
-- Shuah Khan Sr. Linux Kernel Developer Open Source Innovation Group Samsung Research America (Silicon Valley) shuahkh@osg.samsung.com | (970) 217-8978