linux-kernel - WARNING: sysfs: cannot create duplicate filename '/class/backlight/nv

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Date:	Tue, 22 Nov 2011 13:11:41 +0100
From:	Jesús Rodríguez Acosta 
	<jesus.rodriguez.acosta@...il.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: WARNING: sysfs: cannot create duplicate filename '/class/backlight/nv_backlight'

Description:

On laptops using tow graphics cards with the same driver the kernel
tries to create twice the same entry/class to the backlight
controller. This happens since I use pure EFI loader (the second card
were never detected before)

How to reproduce:
 - MacBookPro 5,3 (or any laptop with two graphics cards?)
 - Pure EFI loader (Grub2).
 - Kernel paremeters: nouveau.noaccel=3D1 (nouveau driver hangs the
system in this kind of laptops when tries to activate GPU
acceleration. As far as I know is a known bug/issue/problem in EFI
systems)

Warning message:
[    5.354659] ------------[ cut here ]------------
[    5.354665] WARNING: at fs/sysfs/dir.c:455 sysfs_add_one+0x8c/0xa1()
[    5.354667] Hardware name: MacBookPro5,3
[    5.354668] sysfs: cannot create duplicate filename
'/class/backlight/nv_backlight'
[    5.354670] Modules linked in: fbcon font bitblit softcursor
snd_hda_codec_cirrus nouveau(+) ttm drm_kms_helper drm agpgart tpm_tis
tpm i2c_algo_bit cryptd sg aes_x86_64 i2c_core aes_generic
snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer snd soundcore
snd_page_alloc mxm_wmi btusb arc4 b43 firewire_ohci firewire_core
crc_itu_t hid_apple applesmc usbhid mac80211 usb_storage tpm_bios
hwmon wmi  bluetooth bcm5974 video hid rtc cfg80211 rng_core rfkill
mac_hid apple_bl
[    5.354705] Pid: 417, comm: modprobe Not tainted 3.1.1-gentoo #10
[    5.354707] Call Trace:
[    5.354712]  [<ffffffff810310aa>] ? warn_slowpath_common+0x78/0x8c
[    5.354715]  [<ffffffff8103115f>] ? warn_slowpath_fmt+0x45/0x4a
[    5.354718]  [<ffffffff810f78f5>] ? sysfs_add_one+0x8c/0xa1
[    5.354720]  [<ffffffff810f7fd7>] ? sysfs_do_create_link+0xef/0x187
[    5.354724]  [<ffffffff811eac1d>] ? device_add+0x1fa/0x550
[    5.354728]  [<ffffffff81025f88>] ? complete_all+0x32/0x41
[    5.354731]  [<ffffffff811b85ab>] ? backlight_device_register+0x104/0x17=1
[    5.354755]  [<ffffffffa0338c23>] ?
nouveau_backlight_init+0x139/0x175 [nouveau]
[    5.354773]  [<ffffffffa02f6cb7>] ?
nouveau_connector_create+0x366/0x387 [nouveau]
[    5.354793]  [<ffffffffa032d4bd>] ? nv50_display_create+0x167/0x2bc [nouveau]
[    5.354807]  [<ffffffffa02dd8c0>] ? nouveau_card_init+0xff9/0x11c7 [nouveau]
[    5.354821]  [<ffffffffa02de0a2>] ? nouveau_load+0x542/0x586 [nouveau]
[    5.354823]  [<ffffffff8102631f>] ? should_resched+0x5/0x24
[    5.354830]  [<ffffffffa0248107>] ? drm_get_pci_dev+0x14f/0x259 [drm]
[    5.354834]  [<ffffffff810571ac>] ? arch_local_irq_save+0x14/0x1d
[    5.354838]  [<ffffffff8118ea72>] ? local_pci_probe+0x3d/0x6f
[    5.354840]  [<ffffffff8118f061>] ? pci_device_probe+0x60/0x8e
[    5.354843]  [<ffffffff811eca92>] ? driver_sysfs_add+0x66/0x8d
[    5.354845]  [<ffffffff811ecd2f>] ? driver_probe_device+0xb2/0x142
[    5.354848]  [<ffffffff811ece0e>] ? __driver_attach+0x4f/0x6f
[    5.354850]  [<ffffffff811ecdbf>] ? driver_probe_device+0x142/0x142
[    5.354853]  [<ffffffff811ec019>] ? bus_for_each_dev+0x47/0x72
[    5.354855]  [<ffffffff811ec69f>] ? bus_add_driver+0xa2/0x1f2
[    5.354859]  [<ffffffffa03dc000>] ? 0xffffffffa03dbfff
[    5.354861]  [<ffffffff811ed2a8>] ? driver_register+0x8d/0xf5
[    5.354864]  [<ffffffffa03dc000>] ? 0xffffffffa03dbfff
[    5.354866]  [<ffffffff8118f2ac>] ? __pci_register_driver+0x50/0xbb
[    5.354868]  [<ffffffffa03dc000>] ? 0xffffffffa03dbfff
[    5.354871]  [<ffffffff810002f8>] ? do_one_initcall+0x78/0x130
[    5.354874]  [<ffffffff8105a74d>] ? sys_init_module+0x80/0x1c5
[    5.354877]  [<ffffffff81309852>] ? system_call_fastpath+0x16/0x1b
[    5.354879] ---[ end trace 086fed128c7c39c7 ]---

Attached you'll find a dump of the kernel messages and the kernel config.

And the PCI VGA controllers:
mac ~ # lspci | grep VGA
02:00.0 VGA compatible controller: nVidia Corporation G96 [GeForce
9600M GT] (rev a1)
03:00.0 VGA compatible controller: nVidia Corporation C79 [GeForce
9400M] (rev b1)

Kernel affecteds: At least > 3.0.0, perhaps all.

Importance: Relative :) but EFI loaders are becoming more frequent,
so, could be interesting to check and or fix for the developer/s.

I read that you are improving EFI loading so if I can provide you more
information about my system, this bug or others just let me know.

Thanks for your efforts!
--
Jesus Rodriguez Acosta
http://es.linkedin.com/in/jesusrodriguezacosta
(+34) 653 79 09 64

View attachment "efiboot-nouveau-backlight-error-fulldump.txt" of type "text/plain" (62439 bytes)

View attachment "macbook-pro-5.3-efi-config-3.1.1.txt" of type "text/plain" (80782 bytes)