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Message-ID: <5476E1E7.1030402@canonical.com>
Date: Thu, 27 Nov 2014 09:33:43 +0100
From: Maarten Lankhorst <maarten.lankhorst@...onical.com>
To: Tobias Klausmann <tobias.johannes.klausmann@....thm.de>,
Michael Marineau <mike@...ineau.org>
CC: David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org,
Ben Skeggs <bskeggs@...hat.com>,
dri-devel@...ts.freedesktop.org
Subject: Re: 3.18-rc regression: drm/nouveau: use shared fences for readable
objects
Hey,
Op 27-11-14 om 02:18 schreef Tobias Klausmann:
>
>
> On 26.11.2014 21:29, Michael Marineau wrote:
>> On Mon, Nov 24, 2014 at 11:43 PM, Maarten Lankhorst
>> <maarten.lankhorst@...onical.com> wrote:
>>> Hey,
>>>
>>> Op 22-11-14 om 21:16 schreef Michael Marineau:
>>>> On Nov 22, 2014 11:45 AM, "Michael Marineau" <mike@...ineau.org> wrote:
>>>>> On Nov 22, 2014 8:56 AM, "Maarten Lankhorst" <
>>>> maarten.lankhorst@...onical.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@...onical.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@...onical.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"
>>>>
>>> Oh right, I just remembered what was going on there..
>>> the .wait was a workaround for a bug in the nvif interface. The hangs should be resolved by applying
>>> 7caa63c04029c5882865867470c106ef73eafb2b
>>>
>>> Can you confirm?
>>>
>>> Could you also confirm that 1c6aafb5f1b84fa5 "drm/nouveau: use shared fences for readable objects, EDITED" with the
>>> above commit applied is the first broken commit?
>>>
>>> ~Maarten
>>>
>> I don't follow, 7caa63c04029c5882865867470c106ef73eafb2b precedes
>> those other commits so there is nothing to apply. Just for kicks I
>> tried reverting it but that made no difference in behavior. Did you
>> mean something else?
>>
> No, Maarten brought me on the same track, missing that this commit was already in that branch.
>
> (Please don't remove me from this thread again, as Maarten requested me to do the same he asked you to do, just easier to follow this, thanks)
>
> Tobias
>
Ok that most likely means the interrupt based wait is borked somehow, so lets find out why..
I fear that this happens because of a race in the interface, so my first attempt will rule out abuse of the nvif api by nouveau_fence.c
Can you test below patch with the default wait function?
diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index 515cd9aebb99..c1a4ffebc206 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -52,20 +52,27 @@ nouveau_fctx(struct nouveau_fence *fence)
return container_of(fence->base.lock, struct nouveau_fence_chan, lock);
}
-static void
-nouveau_fence_signal(struct nouveau_fence *fence)
+static int
+nouveau_fence_signal(struct nouveau_fence *fence, int delay)
{
+ int drop = 0;
+
fence_signal_locked(&fence->base);
list_del(&fence->head);
if (test_bit(FENCE_FLAG_USER_BITS, &fence->base.flags)) {
struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
- if (!--fctx->notify_ref)
- nvif_notify_put(&fctx->notify);
+ if (!--fctx->notify_ref) {
+ if (!delay)
+ nvif_notify_put(&fctx->notify);
+ else
+ drop = 1;
+ }
}
fence_put(&fence->base);
+ return drop;
}
static struct nouveau_fence *
@@ -94,7 +101,7 @@ nouveau_fence_context_del(struct nouveau_fence_chan *fctx)
while (!list_empty(&fctx->pending)) {
fence = list_entry(fctx->pending.next, typeof(*fence), head);
- nouveau_fence_signal(fence);
+ nouveau_fence_signal(fence, 0);
fence->channel = NULL;
}
spin_unlock_irq(&fctx->lock);
@@ -112,10 +119,11 @@ nouveau_fence_context_free(struct nouveau_fence_chan *fctx)
kref_put(&fctx->fence_ref, nouveau_fence_context_put);
}
-static void
-nouveau_fence_update(struct nouveau_channel *chan, struct nouveau_fence_chan *fctx)
+static int
+nouveau_fence_update(struct nouveau_channel *chan, struct nouveau_fence_chan *fctx, int delay)
{
struct nouveau_fence *fence;
+ int drop = 0;
u32 seq = fctx->read(chan);
@@ -123,10 +131,12 @@ nouveau_fence_update(struct nouveau_channel *chan, struct nouveau_fence_chan *fc
fence = list_entry(fctx->pending.next, typeof(*fence), head);
if ((int)(seq - fence->base.seqno) < 0)
- return;
+ break;
- nouveau_fence_signal(fence);
+ drop |= nouveau_fence_signal(fence, delay);
}
+
+ return drop;
}
static int
@@ -135,18 +145,20 @@ nouveau_fence_wait_uevent_handler(struct nvif_notify *notify)
struct nouveau_fence_chan *fctx =
container_of(notify, typeof(*fctx), notify);
unsigned long flags;
+ int ret = NVIF_NOTIFY_KEEP;
spin_lock_irqsave(&fctx->lock, flags);
if (!list_empty(&fctx->pending)) {
struct nouveau_fence *fence;
fence = list_entry(fctx->pending.next, typeof(*fence), head);
- nouveau_fence_update(fence->channel, fctx);
+ if (nouveau_fence_update(fence->channel, fctx, 1))
+ ret = NVIF_NOTIFY_DROP;
}
spin_unlock_irqrestore(&fctx->lock, flags);
/* Always return keep here. NVIF refcount is handled with nouveau_fence_update */
- return NVIF_NOTIFY_KEEP;
+ return ret;
}
void
@@ -262,7 +274,7 @@ nouveau_fence_emit(struct nouveau_fence *fence, struct nouveau_channel *chan)
if (!ret) {
fence_get(&fence->base);
spin_lock_irq(&fctx->lock);
- nouveau_fence_update(chan, fctx);
+ nouveau_fence_update(chan, fctx, 0);
list_add_tail(&fence->head, &fctx->pending);
spin_unlock_irq(&fctx->lock);
}
@@ -282,7 +294,7 @@ nouveau_fence_done(struct nouveau_fence *fence)
return true;
spin_lock_irqsave(&fctx->lock, flags);
- nouveau_fence_update(fence->channel, fctx);
+ nouveau_fence_update(fence->channel, fctx, 0);
spin_unlock_irqrestore(&fctx->lock, flags);
}
return fence_is_signaled(&fence->base);
--
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