linux-kernel - Re: intel_check_page_flip()

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Date:	Fri, 29 May 2015 09:26:18 +0300
From:	Jani Nikula <jani.nikula@...ux.intel.com>
To:	Shuah Khan <shuahkh@....samsung.com>, daniel.vetter@...el.com
Cc:	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: Re: intel_check_page_flip() - WARN_ON(!in_interrupt())

On Fri, 29 May 2015, Shuah Khan <shuahkh@....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@....samsung.com | (970) 217-8978

-- 
Jani Nikula, Intel Open Source Technology Center
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