[Intel-gfx] [PATCH] drm/i915: Protect intel_engine_wakeup() for call from irq context
Chris Wilson
chris at chris-wilson.co.uk
Mon Mar 20 14:46:57 UTC 2017
On Mon, Mar 20, 2017 at 02:39:39PM +0000, Tvrtko Ursulin wrote:
>
> On 20/03/2017 14:31, Chris Wilson wrote:
> >intel_engine_wakeup() is called by nop_request_submit() which is
> >installed to handle third party fences completed from within irq
> >context. As such, it needs the full irqsave/irqrestore and not the
> >partial spin_irq_lock handling.
> >
> >[18942.714467] =================================
> >[18942.719076] [ INFO: inconsistent lock state ]
> >[18942.723522] 4.11.0-rc2-CI-CI_DRM_2368+ #1 Tainted: G U W
> >[18942.729970] ---------------------------------
> >[18942.734466] inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
> >[18942.740594] gem_eio/1275 [HC0[0]:SC0[0]:HE1:SE1] takes:
> >[18942.745932] (&(&fence->lock)->rlock){+.?...}, at: [<ffffffff815ec100>] dma_fence_signal+0x100/0x
> >230
> >[18942.755331] {IN-SOFTIRQ-W} state was registered at:
> >[18942.760356] __lock_acquire+0x5d0/0x1bb0
> >[18942.764444] lock_acquire+0xc9/0x220
> >[18942.768196] _raw_spin_lock_irqsave+0x41/0x60
> >[18942.772747] dma_fence_signal+0x100/0x230
> >[18942.776927] vgem_fence_timeout+0x9/0x10 [vgem]
> >[18942.781701] call_timer_fn+0x92/0x380
> >[18942.785557] expire_timers+0x150/0x1f0
> >[18942.789491] run_timer_softirq+0x7c/0x160
> >[18942.793705] __do_softirq+0x116/0x4c0
> >[18942.797560] irq_exit+0xa9/0xc0
> >[18942.800873] smp_apic_timer_interrupt+0x38/0x50
> >[18942.805611] apic_timer_interrupt+0x90/0xa0
> >[18942.810008] cpuidle_enter_state+0x135/0x380
> >[18942.814503] cpuidle_enter+0x12/0x20
> >[18942.818250] call_cpuidle+0x1e/0x40
> >[18942.821906] do_idle+0x17e/0x1f0
> >[18942.825333] cpu_startup_entry+0x18/0x20
> >[18942.829463] rest_init+0x127/0x130
> >[18942.833025] start_kernel+0x3f1/0x3fe
> >[18942.836908] x86_64_start_reservations+0x2a/0x2c
> >[18942.841733] x86_64_start_kernel+0x173/0x186
> >[18942.846234] verify_cpu+0x0/0xfc
> >[18942.849604] irq event stamp: 30568
> >[18942.853140] hardirqs last enabled at (30567): [<ffffffff8110b81f>] ktime_get+0xef/0x120
> >[18942.861468] hardirqs last disabled at (30568): [<ffffffff81876377>] _raw_spin_lock_irqsave+0x17/0
> >x60
> >[18942.870812] softirqs last enabled at (30462): [<ffffffff81085cd9>] __do_softirq+0x1d9/0x4c0
> >[18942.879443] softirqs last disabled at (30439): [<ffffffff81086139>] irq_exit+0xa9/0xc0
> >[18942.887616]
> >[18942.887616] other info that might help us debug this:
> >[18942.894279] Possible unsafe locking scenario:
> >[18942.894279]
> >[18942.900336] CPU0
> >[18942.902851] ----
> >[18942.905362] lock(&(&fence->lock)->rlock);
> >[18942.909647] <Interrupt>
> >[18942.912330] lock(&(&fence->lock)->rlock);
> >[18942.916821]
> >[18942.916821] *** DEADLOCK ***
> >[18942.916821]
> >[18942.922862] 1 lock held by gem_eio/1275:
> >[18942.926859] #0: (&(&fence->lock)->rlock){+.?...}, at: [<ffffffff815ec100>] dma_fence_signal+0x1
> >00/0x230
> >[18942.936651]
> >[18942.936651] stack backtrace:
> >[18942.941142] CPU: 3 PID: 1275 Comm: gem_eio Tainted: G U W 4.11.0-rc2-CI-CI_DRM_2368+ #
> >1
> >[18942.950367] Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F21 01/06/2
> >017
> >[18942.959756] Call Trace:
> >[18942.962244] dump_stack+0x67/0x92
> >[18942.965626] print_usage_bug.part.23+0x259/0x268
> >[18942.970362] mark_lock+0x12c/0x6f0
> >[18942.973851] ? check_usage_forwards+0x130/0x130
> >[18942.978487] mark_held_locks+0x6f/0xa0
> >[18942.982329] ? _raw_spin_unlock_irq+0x27/0x50
> >[18942.986797] trace_hardirqs_on_caller+0x150/0x200
> >[18942.991599] trace_hardirqs_on+0xd/0x10
> >[18942.995515] _raw_spin_unlock_irq+0x27/0x50
> >[18942.999796] intel_engine_wakeup+0x26/0x30 [i915]
> >[18943.004670] intel_engine_init_global_seqno+0x131/0x1a0 [i915]
> >[18943.010745] nop_submit_request+0x2e/0x40 [i915]
> >[18943.015476] submit_notify+0x3f/0x5c [i915]
> >[18943.019763] __i915_sw_fence_complete+0x176/0x220 [i915]
> >[18943.025234] ? try_to_del_timer_sync+0x4d/0x60
> >[18943.029825] i915_sw_fence_complete+0x25/0x40 [i915]
> >[18943.034887] dma_i915_sw_fence_wake+0x26/0x60 [i915]
> >[18943.039959] dma_fence_signal+0x146/0x230
> >[18943.044109] vgem_fence_signal_ioctl+0x6c/0xc0 [vgem]
> >[18943.049275] drm_ioctl+0x200/0x450
> >[18943.052758] ? vgem_fence_attach_ioctl+0x270/0x270 [vgem]
> >[18943.058334] do_vfs_ioctl+0x90/0x6e0
> >[18943.061991] ? entry_SYSCALL_64_fastpath+0x5/0xb1
> >[18943.066843] ? __this_cpu_preempt_check+0x13/0x20
> >[18943.071643] ? trace_hardirqs_on_caller+0xe7/0x200
> >[18943.076532] SyS_ioctl+0x3c/0x70
> >[18943.079842] entry_SYSCALL_64_fastpath+0x1c/0xb1
> >[18943.084558] RIP: 0033:0x7f0dfcc14357
> >[18943.088240] RSP: 002b:00007ffeb4628da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> >[18943.095996] RAX: ffffffffffffffda RBX: ffffffff8147eb93 RCX: 00007f0dfcc14357
> >[18943.103311] RDX: 00007ffeb4628de0 RSI: 0000000040086442 RDI: 0000000000000005
> >[18943.110574] RBP: ffffc9000176ff88 R08: 0000000000000004 R09: 0000000000000000
> >[18943.117845] R10: 0000000000000029 R11: 0000000000000246 R12: 0000000000000001
> >[18943.125168] R13: 0000000000000005 R14: 0000000040086442 R15: 0000000000000000
> >[18943.132520] ? __this_cpu_preempt_check+0x13/0x20
> >
> >Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> >---
> > drivers/gpu/drm/i915/intel_breadcrumbs.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >index ba986edee312..b6ea192ad550 100644
> >--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >@@ -47,11 +47,12 @@ static unsigned int __intel_breadcrumbs_wakeup(struct intel_breadcrumbs *b)
> > unsigned int intel_engine_wakeup(struct intel_engine_cs *engine)
> > {
> > struct intel_breadcrumbs *b = &engine->breadcrumbs;
> >+ unsigned long flags;
> > unsigned int result;
> >
> >- spin_lock_irq(&b->irq_lock);
> >+ spin_lock_irqsave(&b->irq_lock, flags);
> > result = __intel_breadcrumbs_wakeup(b);
> >- spin_unlock_irq(&b->irq_lock);
> >+ spin_unlock_irqrestore(&b->irq_lock, flags);
> >
> > return result;
> > }
> >
>
> My bad, sorry!
>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
My r-b, so I'm just as culpable. Since this is actually a clean revert,
I'll mark it up.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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