From: "jun.miao" <jun.miao@windriver.com>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
jani.nikula@linux.intel.com, daniel@ffwll.ch, airlied@linux.ie
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH][V2] drm/i915/gt: Fix a lockdep warning on RT kernel
Date: Thu, 15 Apr 2021 20:41:02 +0800 [thread overview]
Message-ID: <1606bffe-f8c9-b619-9647-483393f87105@windriver.com> (raw)
In-Reply-To: <338067c3-406e-a617-3efa-824787793e43@linux.intel.com>
On 4/15/21 7:12 PM, Tvrtko Ursulin wrote:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
>
> Hi,
>
> On 14/04/2021 15:48, Jun Miao wrote:
>> Don`t simple disable all the HD-irq, should race the region in the
>> intel_breadcrumbs_disarm_irq() only.
>>
>
> What is HD-irq, I am, not familiar with that term?
Disable local interrupt delivery from Hardware of cpu.:-)
Thanks,
Jun
>
>> BUG: sleeping function called from invalid context at
>> kernel/locking/rtmutex.c:969
>> #0: ffff89c4c00ca970 ((wq_completion)events){+.+.}-{0:0}, at:
>> process_one_work+0x1cf/0x6d0
>> #1: ffffa433c1f53e60
>> ((work_completion)(&engine->retire_work)){+.+.}-{0:0}, at:
>> process_one_work+0x1cf 0x6d
>> #2: ffff89c4ccb0a0a8 (kernel_context){+.+.}-{0:0}, at:
>> engine_retire+0x62/0x110 [i915]
>> #3: ffff89c4cf682300 (wakeref.mutex#3){+.+.}-{0:0}, at:
>> __intel_wakeref_put_last+0x20/0x60 [i915]
>> #4: ffff89c4ccb08398 (&b->irq_lock){+.+.}-{0:0}, at:
>> intel_breadcrumbs_disarm_irq+0x20/0xd0 [i915]
>> irq event stamp: 2126
>> hardirqs last enabled at (2125): [<ffffffffbb134739>]
>> cancel_delayed_work+0xa9/0xc0
>> hardirqs last disabled at (2126): [<ffffffffc0507fe6>]
>> __intel_breadcrumbs_park+0x76/0x80 [i915]
>> softirqs last enabled at (0): [<ffffffffbb1099ce>]
>> copy_process+0x63e/0x1630
>> softirqs last disabled at (0): [<0000000000000000>] 0x0
>> CPU: 3 PID: 281 Comm: kworker/3:3 Not tainted
>> 5.10.27-rt34-yocto-preempt-rt #1
>> Hardware name: Intel(R) Client Systems NUC7i5DNKE/NUC7i5DNB, BIOS
>> DNKBLi5v.86A.0064.2019.0523.1933 05/23 2019
>> Workqueue: events engine_retire [i915]
>> Call Trace:
>> show_stack+0x52/0x58
>> dump_stack+0x7d/0x9f
>> ___might_sleep.cold+0xe3/0xf4
>> rt_spin_lock+0x3f/0xc0
>> ? intel_breadcrumbs_disarm_irq+0x20/0xd0 [i915]
>> intel_breadcrumbs_disarm_irq+0x20/0xd0 [i915]
>> signal_irq_work+0x241/0x660 [i915]
>> ? __this_cpu_preempt_check+0x13/0x20
>> ? lockdep_hardirqs_off+0x106/0x120
>> __intel_breadcrumbs_park+0x3f/0x80 [i915]
>> __engine_park+0xbd/0xe0 [i915]
>> ____intel_wakeref_put_last+0x22/0x60 [i915]
>> __intel_wakeref_put_last+0x50/0x60 [i915]
>> intel_context_exit_engine+0x5f/0x70 [i915]
>> i915_request_retire+0x139/0x2d0 [i915]
>> engine_retire+0xb0/0x110 [i915]
>> process_one_work+0x26d/0x6d0
>> worker_thread+0x53/0x330
>> kthread+0x1b0/0x1d0
>> ? process_one_work+0x6d0/0x6d0
>> ? __kthread_parkme+0xc0/0xc0
>> ret_from_fork+0x22/0x30
>>
>> Fixes: 9d5612ca165a ("drm/i915/gt: Defer enabling the breadcrumb
>> interrupt to after submission")
>> Signed-off-by: Jun Miao <jun.miao@windriver.com>
>> ---
>> drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
>> b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
>> index 34a645d..0589b1a 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
>> @@ -103,10 +103,12 @@ static void
>> __intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b)
>>
>> static void intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b)
>> {
>> - spin_lock(&b->irq_lock);
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&b->irq_lock, flags);
>> if (b->irq_armed)
>> __intel_breadcrumbs_disarm_irq(b);
>> - spin_unlock(&b->irq_lock);
>> + spin_unlock_irqrestore(&b->irq_lock, flags);
>> }
>>
>> static void add_signaling_context(struct intel_breadcrumbs *b,
>> @@ -337,9 +339,7 @@ void __intel_breadcrumbs_park(struct
>> intel_breadcrumbs *b)
>> /* Kick the work once more to drain the signalers, and disarm
>> the irq */
>> irq_work_sync(&b->irq_work);
>> while (READ_ONCE(b->irq_armed) && !atomic_read(&b->active)) {
>> - local_irq_disable();
>> signal_irq_work(&b->irq_work);
>> - local_irq_enable();
>
> Unfortunately there is another lock inside signal_irq_work (rq->lock)
> which needs to be taken irq safe.
>
Ok, i will change the left spin_lock -> spin_lock_irqsave.
In fact, inside signal_irq_work, intel_breadcrumbs_arm_irq
(&b->irq_lock) which also needs to be taken irq safe.
Thanks,
Jun
> RT patches are in tree or out of the tree these days?
I base on the mainline kernel tree, and this BUG warning will not
happen. But RT v5.10 will complain "BUG warning", so i want this patch
will solve RT WARNING without affecting mainline performance in mainline
tree.
Thanks,
Jun
>
> Regards,
>
> Tvrtko
>
>> cond_resched();
>> }
>> }
>>
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next prev parent reply other threads:[~2021-04-19 12:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-14 14:48 [Intel-gfx] [PATCH][V2] drm/i915/gt: Fix a lockdep warning on RT kernel Jun Miao
2021-04-15 9:53 ` [Intel-gfx] ✗ Fi.CI.DOCS: warning for " Patchwork
2021-04-15 10:21 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2021-04-15 11:12 ` [Intel-gfx] [PATCH][V2] " Tvrtko Ursulin
2021-04-15 12:41 ` jun.miao [this message]
2021-04-19 8:57 ` Tvrtko Ursulin
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