[PATCH 1/2] drm/amdgpu: change job_list_lock to mutex
zhoucm1
david1.zhou at amd.com
Tue Jun 28 10:05:30 UTC 2016
On 2016年06月28日 18:03, Christian König wrote:
> Am 28.06.2016 um 11:33 schrieb zhoucm1:
>>
>>
>> On 2016年06月28日 17:36, Christian König wrote:
>>> Am 28.06.2016 um 09:27 schrieb Huang Rui:
>>>> On Tue, Jun 28, 2016 at 03:04:18PM +0800, Chunming Zhou wrote:
>>>>> ring_mirror_list is only used kthread context, no need to spinlock.
>>>>> otherwise deadlock happens when kthread_park.
>>>>>
>>>> Yes, in process context, we prefer to use mutex, because it avoids to
>>>> grab the CPU all the time.
>>>>
>>>> Reviewed-by: Huang Rui <ray.huang at amd.com>
>>>
>>> NAK, the patch won't apply because I've changed the irq save spin
>>> lock to a normal one quite a while ago. But, I'm not sure if Alex
>>> picked up that patch yet.
>>>
>>> You shouldn't use a mutex here when you don't have a reason to do
>>> so. Spin locks have less overhead and we won't expect any contention
>>> here.
>>>
>>> Additional to that how should this cause a deadlock with kthread_park?
>> you can apply another patch to drop hw ring, and then run glxgears,
>> and hang the gfx with the attached, then you will find that deadlock
>> info.
>
> Please provide the deadlock info. Since the spin lock only protects
> the linked list we should be able to easily avoid any lock inversion
> which could lead to a deadlock.
With the latest code, you could easily reproduce it with above steps,
after mutex, these deadlock info disappears:
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.282892] NMI
watchdog: BUG: soft lockup - CPU#7 stuck for 22s! [kworker/7:0:58]
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283106]
Modules linked in: amdgpu(OE) ttm(OE) drm_kms_helper(OE) drm(E)
i2c_algo_bit(E) fb_sys_fops(E) syscopyarea(E) sysfillrect(E)
sysimgblt(E) nfsv3(E) bnep(E) rfcomm(E) bluetooth(E) rpcsec_gss_krb5(E)
nfsv4(E) nfsd(E) auth_rpcgss(E) nfs_acl(E) nfs(E) lockd(E) grace(E)
sunrpc(E) fscache(E) binfmt_misc(E) snd_hda_codec_realtek(E)
snd_hda_codec_hdmi(E) snd_hda_codec_generic(E) snd_hda_intel(E)
snd_hda_codec(E) snd_hda_core(E) snd_hwdep(E) coretemp(E) snd_pcm(E)
snd_seq_midi(E) snd_seq_midi_event(E) snd_rawmidi(E) snd_seq(E)
joydev(E) kvm_intel(E) snd_seq_device(E) snd_timer(E) kvm(E) snd(E)
soundcore(E) irqbypass(E) gpio_ich(E) mxm_wmi(E) serio_raw(E) shpchp(E)
wmi(E) i7core_edac(E) edac_core(E) lpc_ich(E) parport_pc(E) mac_hid(E)
ppdev(E) lp(E) parport(E) hid_generic(E) usbhid(E) hid(E)
firewire_ohci(E) 8139too(E) pata_acpi(E) firewire_core(E) 8139cp(E)
crc_itu_t(E) r8169(E) mii(E) pata_jmicron(E) ahci(E) libahci(E)
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283134] CPU:
7 PID: 58 Comm: kworker/7:0 Tainted: G IOE 4.5.0-custom #7
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283136]
Hardware name: Gigabyte Technology Co., Ltd. X58A-UD3R/X58A-UD3R, BIOS
FE 12/23/2010
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283182]
Workqueue: events amd_sched_job_finish [amdgpu]
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283183] task:
ffff8801a8490000 ti: ffff8801a848c000 task.ti: ffff8801a848c000
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283184] RIP:
0010:[<ffffffff810c1131>] [<ffffffff810c1131>]
native_queued_spin_lock_slowpath+0x171/0x190
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283189] RSP:
0018:ffff8801a848fdc8 EFLAGS: 00000202
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283190] RAX:
0000000000000101 RBX: ffff8800c5ba1030 RCX: 0000000000000001
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283191] RDX:
0000000000000101 RSI: 0000000000000001 RDI: ffff8800c42a4518
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283192] RBP:
ffff8801a848fdc8 R08: 0000000000000101 R09: ffff8801a93d6300
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283193] R10:
0000000000000001 R11: 0000000000000000 R12: ffff8800c42a4468
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283194] R13:
ffff8800c42a4518 R14: ffff8800c5ba1000 R15: ffff8800c5ba1030
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283195] FS:
0000000000000000(0000) GS:ffff8801a93c0000(0000) knlGS:0000000000000000
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283196] CS:
0010 DS: 0000 ES: 0000 CR0: 000000008005003b
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283197] CR2:
00007efc3bc21e50 CR3: 0000000001c0c000 CR4: 00000000000006e0
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283198] Stack:
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283199]
ffff8801a848fdd8 ffffffff81173ef2 ffff8801a848fde8 ffffffff817a19c0
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283200]
ffff8801a848fe18 ffffffffa06937fb ffff8801a75deb40 ffff8801a93d6300
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283202]
ffff8801a93dae00 00000000000001c0 ffff8801a848fe60 ffffffff81090bb0
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283203] Call
Trace:
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283206]
[<ffffffff81173ef2>] queued_spin_lock_slowpath+0xb/0xf
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283209]
[<ffffffff817a19c0>] _raw_spin_lock+0x20/0x30
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283234]
[<ffffffffa06937fb>] amd_sched_job_finish+0x2b/0xc0 [amdgpu]
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283237]
[<ffffffff81090bb0>] process_one_work+0x150/0x3f0
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283239]
[<ffffffff8109136b>] worker_thread+0x12b/0x4b0
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283241]
[<ffffffff81091240>] ? rescuer_thread+0x340/0x340
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283242]
[<ffffffff81096b22>] kthread+0xd2/0xf0
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283244]
[<ffffffff81096a50>] ? kthread_park+0x50/0x50
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283246]
[<ffffffff817a210f>] ret_from_fork+0x3f/0x70
Jun 28 14:34:25 zhoucm1-System-Product-Name kernel: [ 96.283247]
[<ffffffff81096a50>] ? kthread_park+0x50/0x50
Regards,
David Zhou
>
> BTW: The debug patch you attached is not such a good idea either,
> cause you modify the gfx ring from outside the worker thread.
>
> Regards,
> Christian.
>
>>
>> Regards,
>> David Zhou
>>>
>>> Regards,
>>> Christian.
>>>
>>>>
>>>>> Change-Id: I906022297015faf14a0ddb5f62a728af3e5f9448
>>>>> Signed-off-by: Chunming Zhou <David1.Zhou at amd.com>
>>>>> ---
>>>>> drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 12 +++++-------
>>>>> drivers/gpu/drm/amd/scheduler/gpu_scheduler.h | 2 +-
>>>>> 2 files changed, 6 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>>>> b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>>>> index b53cf58..3373d97 100644
>>>>> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>>>> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>>>> @@ -331,10 +331,9 @@ static void amd_sched_job_finish(struct
>>>>> work_struct *work)
>>>>> struct amd_sched_job *s_job = container_of(work, struct
>>>>> amd_sched_job,
>>>>> finish_work);
>>>>> struct amd_gpu_scheduler *sched = s_job->sched;
>>>>> - unsigned long flags;
>>>>> /* remove job from ring_mirror_list */
>>>>> - spin_lock_irqsave(&sched->job_list_lock, flags);
>>>>> + mutex_lock(&sched->job_list_lock);
>>>>> list_del_init(&s_job->node);
>>>>> if (sched->timeout != MAX_SCHEDULE_TIMEOUT) {
>>>>> struct amd_sched_job *next;
>>>>> @@ -348,7 +347,7 @@ static void amd_sched_job_finish(struct
>>>>> work_struct *work)
>>>>> if (next)
>>>>> schedule_delayed_work(&next->work_tdr, sched->timeout);
>>>>> }
>>>>> - spin_unlock_irqrestore(&sched->job_list_lock, flags);
>>>>> + mutex_unlock(&sched->job_list_lock);
>>>>> sched->ops->free_job(s_job);
>>>>> }
>>>>> @@ -362,15 +361,14 @@ static void amd_sched_job_finish_cb(struct
>>>>> fence *f, struct fence_cb *cb)
>>>>> static void amd_sched_job_begin(struct amd_sched_job *s_job)
>>>>> {
>>>>> struct amd_gpu_scheduler *sched = s_job->sched;
>>>>> - unsigned long flags;
>>>>> - spin_lock_irqsave(&sched->job_list_lock, flags);
>>>>> + mutex_lock(&sched->job_list_lock);
>>>>> list_add_tail(&s_job->node, &sched->ring_mirror_list);
>>>>> if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
>>>>> list_first_entry_or_null(&sched->ring_mirror_list,
>>>>> struct amd_sched_job, node) == s_job)
>>>>> schedule_delayed_work(&s_job->work_tdr, sched->timeout);
>>>>> - spin_unlock_irqrestore(&sched->job_list_lock, flags);
>>>>> + mutex_unlock(&sched->job_list_lock);
>>>>> }
>>>>> static void amd_sched_job_timedout(struct work_struct *work)
>>>>> @@ -564,7 +562,7 @@ int amd_sched_init(struct amd_gpu_scheduler
>>>>> *sched,
>>>>> init_waitqueue_head(&sched->wake_up_worker);
>>>>> init_waitqueue_head(&sched->job_scheduled);
>>>>> INIT_LIST_HEAD(&sched->ring_mirror_list);
>>>>> - spin_lock_init(&sched->job_list_lock);
>>>>> + mutex_init(&sched->job_list_lock);
>>>>> atomic_set(&sched->hw_rq_count, 0);
>>>>> if (atomic_inc_return(&sched_fence_slab_ref) == 1) {
>>>>> sched_fence_slab = kmem_cache_create(
>>>>> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
>>>>> b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
>>>>> index 221a515..5675906 100644
>>>>> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
>>>>> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
>>>>> @@ -132,7 +132,7 @@ struct amd_gpu_scheduler {
>>>>> atomic_t hw_rq_count;
>>>>> struct task_struct *thread;
>>>>> struct list_head ring_mirror_list;
>>>>> - spinlock_t job_list_lock;
>>>>> + struct mutex job_list_lock;
>>>>> };
>>>>> int amd_sched_init(struct amd_gpu_scheduler *sched,
>>>>> --
>>>>> 1.9.1
>>>>>
>>>>> _______________________________________________
>>>>> amd-gfx mailing list
>>>>> amd-gfx at lists.freedesktop.org
>>>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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>>
>>
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