On Mon, 28 Sep 2015, Jens Axboe wrote:
> Hi,
>
> Running 4.3-rc on a new laptop, and I notice that I get these whenever
> powertop --auto-tune is run:
>
> [14954.927920] [ cut here ]
> [14954.927926] WARNING: CPU: 1 PID: 14297 at drivers/gpu/drm/drm_atomic.c:889
> drm_atomic_get_property+0x232/0x2b0()
> [14954.927927] Modules linked in: msr drbg ctr ccm cmac uvcvideo hid_generic
> videobuf2_vmalloc videobuf2_memops videobuf2_core v4l2_common videodev usbhid
> btusb btintel arc4 iwlmvm mac80211 joydev snd_hda_codec_realtek
> snd_hda_codec_generic x86_pkg_temp_thermal snd_hda_codec_hdmi
> intel_powerclamp kvm_intel dell_laptop dell_wmi dcdbas snd_hda_intel
> hid_multitouch kvm sparse_keymap iwlwifi snd_hda_codec snd_hwdep snd_hda_core
> aesni_intel aes_x86_64 glue_helper ehci_pci lrw gf128mul xhci_pci ablk_helper
> cfg80211 cryptd xhci_hcd ehci_hcd snd_pcm int3403_thermal snd_seq_midi bnep
> snd_seq_midi_event rfcomm snd_rawmidi bluetooth snd_seq snd_timer
> snd_seq_device processor_thermal_device snd intel_soc_dts_iosf iosf_mbi
> i2c_hid hid i2c_designware_platform i2c_designware_core int3402_thermal
> int3400_thermal int340x_thermal_zone acpi_thermal_rel soundcore binfmt_misc
> nls_iso8859_1 nls_cp437 fuse vfat fat
> [14954.927963] CPU: 1 PID: 14297 Comm: powertop Tainted: G U W
> 4.3.0-rc3+ #177
> [14954.927964] Hardware name: Dell Inc. XPS 13 9343/0310JH, BIOS A05
> 07/14/2015
> [14954.927965] 81a7c2db 8800032e3c88 812923a9
>
> [14954.927967] 8800032e3cc0 81050aa6 880215577028
> 88021551df80
> [14954.927968] 880215577000 880133e2ea80 88020ea59000
> 8800032e3cd0
> [14954.927970] Call Trace:
> [14954.927974] [] dump_stack+0x4b/0x72
> [14954.927976] [] warn_slowpath_common+0x86/0xc0
> [14954.927978] [] warn_slowpath_null+0x1a/0x20
> [14954.927980] [] drm_atomic_get_property+0x232/0x2b0
> [14954.927982] [] drm_object_property_get_value+0x6c/0x70
> [14954.927984] [] dpms_show+0x2f/0x70
> [14954.927987] [] dev_attr_show+0x20/0x50
> [14954.927989] [] sysfs_kf_seq_show+0xa3/0x140
> [14954.927990] [] kernfs_seq_show+0x20/0x30
> [14954.927993] [] seq_read+0xcd/0x370
> [14954.927994] [] kernfs_fop_read+0x107/0x160
> [14954.927996] [] __vfs_read+0x28/0xd0
> [14954.927999] [] ? security_file_permission+0xa3/0xc0
> [14954.928001] [] ? rw_verify_area+0x53/0xf0
> [14954.928002] [] vfs_read+0x86/0x130
> [14954.928004] [] SyS_read+0x46/0xa0
> [14954.928007] [] entry_SYSCALL_64_fastpath+0x12/0x6a
> [14954.928008] ---[ end trace b1d297c2aeff3470 ]---
>
> Looks like we're missing a modeset lock/unlock around the property
> retrieval from the sysfs path. Below patch works for me.
Daniel's alternative at
http://mid.gmane.org/1443513413-28873-1-git-send-email-daniel.vetter at ffwll.ch
>
> Signed-off-by: Jens Axboe
>
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index 0f6cd33b531f..2b62166f6b2a 100644
> --- a/drivers/gpu/drm/drm_sysfs.c
> +++ b/drivers/gpu/drm/drm_sysfs.c
> @@ -239,9 +239,12 @@ static ssize_t dpms_show(struct device *device,
> uint64_t dpms_status;
> int ret;
>
> + drm_modeset_lock(>mode_config.connection_mutex, NULL);
> ret = drm_object_property_get_value(>base,
> dev->mode_config.dpms_property,
> _status);
> + drm_modeset_unlock(>mode_config.connection_mutex);
> +
> if (ret)
> return 0;
>
>
> --
> Jens Axboe
>
> ___
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> dri-devel at lists.freedesktop.org
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--
Jani Nikula, Intel Open Source Technology Center
