3.18-rc regression: drm/nouveau: use shared fences for readable objects

Michael Marineau mike at marineau.org
Sat Nov 22 12:16:44 PST 2014


On Nov 22, 2014 11:45 AM, "Michael Marineau" <mike at marineau.org> wrote:
>
>
> On Nov 22, 2014 8:56 AM, "Maarten Lankhorst" <
maarten.lankhorst at canonical.com> wrote:
> >
> > Hey,
> >
> > Op 22-11-14 om 01:19 schreef Michael Marineau:
> > > On Thu, Nov 20, 2014 at 12:53 AM, Maarten Lankhorst
> > > <maarten.lankhorst at canonical.com> wrote:
> > >> Op 20-11-14 om 05:06 schreef Michael Marineau:
> > >>> On Wed, Nov 19, 2014 at 12:10 AM, Maarten Lankhorst
> > >>> <maarten.lankhorst at canonical.com> wrote:
> > >>>> Hey,
> > >>>>
> > >>>> On 19-11-14 07:43, Michael Marineau wrote:
> > >>>>> On 3.18-rc kernel's I have been intermittently experiencing GPU
> > >>>>> lockups shortly after startup, accompanied with one or both of the
> > >>>>> following errors:
> > >>>>>
> > >>>>> nouveau E[   PFIFO][0000:01:00.0] read fault at 0x000734a000 [PTE]
> > >>>>> from PBDMA0/HOST_CPU on channel 0x007faa3000 [unknown]
> > >>>>> nouveau E[     DRM] GPU lockup - switching to software fbcon
> > >>>>>
> > >>>>> I was able to trace the issue with bisect to commit
> > >>>>> 809e9447b92ffe1346b2d6ec390e212d5307f61c "drm/nouveau: use shared
> > >>>>> fences for readable objects". The lockups appear to have cleared
up
> > >>>>> since reverting that and a few related followup commits:
> > >>>>>
> > >>>>> 809e9447: "drm/nouveau: use shared fences for readable objects"
> > >>>>> 055dffdf: "drm/nouveau: bump driver patchlevel to 1.2.1"
> > >>>>> e3be4c23: "drm/nouveau: specify if interruptible wait is desired
in
> > >>>>> nouveau_fence_sync"
> > >>>>> 15a996bb: "drm/nouveau: assign fence_chan->name correctly"
> > >>>> Weird. I'm not sure yet what causes it.
> > >>>>
> > >>>>
http://cgit.freedesktop.org/~mlankhorst/linux/commit/?h=fixed-fences-for-bisect&id=86be4f216bbb9ea3339843a5658d4c21162c7ee2
> > >>> Building a kernel from that commit gives me an entirely new
behavior:
> > >>> X hangs for at least 10-20 seconds at a time with brief moments of
> > >>> responsiveness before hanging again while gitk on the kernel repo
> > >>> loads. Otherwise the system is responsive. The head of that
> > >>> fixed-fences-for-bisect branch (1c6aafb5) which is the "use shared
> > >>> fences for readable objects" commit I originally bisected to does
> > >>> feature the complete lockups I was seeing before.
> > >> Ok for the sake of argument lets just assume they're separate bugs,
and we should look at xorg
> > >> hanging first.
> > >>
> > >> Is there anything in the dmesg when the hanging happens?
> > >>
> > >> And it's probably 15 seconds, if it's called through
nouveau_fence_wait.
> > >>
> > >> Try changing else if (!ret) to else if (WARN_ON(!ret)) in that
function, and see if you get some dmesg spam. :)
> > > Adding the WARN_ON to 86be4f21 repots the following:
> > >
> > > [ 1188.676073] ------------[ cut here ]------------
> > > [ 1188.676161] WARNING: CPU: 1 PID: 474 at
> > > drivers/gpu/drm/nouveau/nouveau_fence.c:359
> > > nouveau_fence_wait.part.9+0x33/0x40 [nouveau]()
> > > [ 1188.676166] Modules linked in: rndis_host cdc_ether usbnet mii bnep
> > > ecb btusb bluetooth rfkill bridge stp llc hid_generic usb_storage
> > > joydev mousedev hid_apple usbhid bcm5974 nls_iso8859_1 nls_cp437 vfat
> > > fat nouveau snd_hda_codec_hdmi coretemp x86_pkg_temp_thermal
> > > intel_powerclamp kvm_intel kvm iTCO_wdt crct10dif_pclmul
> > > iTCO_vendor_support crc32c_intel evdev aesni_intel mac_hid aes_x86_64
> > > lrw glue_helper ablk_helper applesmc snd_hda_codec_cirrus cryptd
> > > input_polldev snd_hda_codec_generic mxm_wmi led_class wmi microcode
> > > hwmon snd_hda_intel ttm snd_hda_controller lpc_ich i2c_i801 mfd_core
> > > snd_hda_codec i2c_algo_bit snd_hwdep drm_kms_helper snd_pcm sbs drm
> > > apple_gmux i2ccore snd_timer snd agpgart mei_me soundcore sbshc mei
> > > video xhci_hcd usbcore usb_common apple_bl button battery ac efivars
> > > autofs4
> > > [ 1188.676300]  efivarfs
> > > [ 1188.676308] CPU: 1 PID: 474 Comm: Xorg Tainted: G        W
> > > 3.17.0-rc2-nvtest+ #147
> > > [ 1188.676313] Hardware name: Apple Inc.
> > > MacBookPro11,3/Mac-2BD1B31983FE1663, BIOS
> > > MBP112.88Z.0138.B11.1408291503 08/29/2014
> > > [ 1188.676316]  0000000000000009 ffff88045daebce8 ffffffff814f0c09
> > > 0000000000000000
> > > [ 1188.676325]  ffff88045daebd20 ffffffff8104ea5d ffff88006a6c1468
> > > 00000000fffffff0
> > > [ 1188.676333]  0000000000000000 0000000000000000 ffff88006a6c1000
> > > ffff88045daebd30
> > > [ 1188.676341] Call Trace:
> > > [ 1188.676356]  [<ffffffff814f0c09>] dump_stack+0x4d/0x66
> > > [ 1188.676369]  [<ffffffff8104ea5d>] warn_slowpath_common+0x7d/0xa0
> > > [ 1188.676377]  [<ffffffff8104eb3a>] warn_slowpath_null+0x1a/0x20
> > > [ 1188.676439]  [<ffffffffc04dd523>]
> > > nouveau_fence_wait.part.9+0x33/0x40 [nouveau]
> > > [ 1188.676496]  [<ffffffffc04ddfe6>] nouveau_fence_wait+0x16/0x30
[nouveau]
> > > [ 1188.676552]  [<ffffffffc04e598f>]
> > > nouveau_gem_ioctl_cpu_prep+0xef/0x1f0 [nouveau]
> > > [ 1188.676578]  [<ffffffffc01c2f4c>] drm_ioctl+0x1ec/0x660 [drm]
> > > [ 1188.676590]  [<ffffffff814f9026>] ?
_raw_spin_unlock_irqrestore+0x36/0x70
> > > [ 1188.676600]  [<ffffffff81094f6d>] ? trace_hardirqs_on+0xd/0x10
> > > [ 1188.676655]  [<ffffffffc04da5b4>] nouveau_drm_ioctl+0x54/0xc0
[nouveau]
> > > [ 1188.676663]  [<ffffffff811a8950>] do_vfs_ioctl+0x300/0x520
> > > [ 1188.676671]  [<ffffffff814f9e55>] ? sysret_check+0x22/0x5d
> > > [ 1188.676677]  [<ffffffff811a8bb1>] SyS_ioctl+0x41/0x80
> > > [ 1188.676683]  [<ffffffff814f9e29>] system_call_fastpath+0x16/0x1b
> > > [ 1188.676688] ---[ end trace 6f7a510865b4674f ]---
> > >
> > > Here are the fence events that fired during that particular
fence_wait:
> > >             Xorg   474 [004]  1173.667645: fence:fence_wait_start:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56910
> > >             Xorg   474 [004]  1173.667647: fence:fence_enable_signal:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56910
> > >          swapper     0 [007]  1173.667688: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56900
> > >          swapper     0 [007]  1173.667692: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56900
> > >          swapper     0 [007]  1173.667839: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56901
> > >          swapper     0 [007]  1173.667842: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56901
> > >          swapper     0 [007]  1173.668021: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56902
> > >          swapper     0 [007]  1173.668482: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56903
> > >          swapper     0 [007]  1173.668485: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56903
> > >          swapper     0 [007]  1173.668489: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56904
> > >          swapper     0 [007]  1173.668496: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56905
> > >          swapper     0 [007]  1173.668499: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56905
> > >          swapper     0 [007]  1173.668502: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56906
> > >          swapper     0 [007]  1173.668505: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56907
> > >          swapper     0 [007]  1173.668508: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56907
> > >          swapper     0 [007]  1173.668511: fence:fence_signaled:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56908
> > >          swapper     0 [007]  1173.668513: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56908
> > >      kworker/4:1    80 [004]  1173.676265: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56896
> > >      kworker/4:1    80 [004]  1173.676273: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56898
> > >      kworker/4:1    80 [004]  1173.676277: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56902
> > >      kworker/4:1    80 [004]  1173.676280: fence:fence_destroy:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56904
> > >             Xorg   474 [001]  1188.676067: fence:fence_wait_end:
> > > driver=nouveau timeline=Xorg[474] context=2 seqno=56910
> > >
> > > I assume that excludes the context you really want so the full fence
> > > event log and corresponding dmesg output are attached.
> >
> > Yep, the trace events are useful. The fence is emitted and presumably
no event is fired after emission.
> >
> > Lets find out if the nvif crap is buggy or it's a result of some other
issue, what happens when you change:
> > .wait = fence_default_wait,
> > to
> > .wait = nouveau_fence_wait_legacy,
> > in nouveau_fence.c?
>
> That change works just fine.

The xorg hangs also appear to be resolved by db1cf46 "drm/nouveau: use rcu
in nouveau_gem_ioctl_cpu_prep"
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