[04/20] drm/i915/execlists: Cancel breadcrumb on preempting the virtual engine
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Message ID 20190718070024.21781-4-chris@chris-wilson.co.uk
State New
Headers show
Series
  • [01/20] drm/i915: Move aliasing_ppgtt underneath its i915_ggtt
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Commit Message

Chris Wilson July 18, 2019, 7 a.m. UTC
As we unwind the requests for a preemption event, we return a virtual
request back to its original virtual engine (so that it is available for
execution on any of its siblings). In the process, this means that its
breadcrumb should no longer be associated with the original physical
engine, and so we are forced to decouple it. Previously, as the request
could not complete without our awareness, we would move it to the next
real engine without any danger. However, preempt-to-busy allowed for
requests to continue on the HW and complete in the background as we
unwound, which meant that we could end up retiring the request before
fixing up the breadcrumb link.

[51679.517943] INFO: trying to register non-static key.
[51679.517956] the code is fine but needs lockdep annotation.
[51679.517960] turning off the locking correctness validator.
[51679.517966] CPU: 0 PID: 3270 Comm: kworker/u8:0 Tainted: G     U            5.2.0+ #717
[51679.517971] Hardware name: Intel Corporation NUC7i5BNK/NUC7i5BNB, BIOS BNKBL357.86A.0052.2017.0918.1346 09/18/2017
[51679.518012] Workqueue: i915 retire_work_handler [i915]
[51679.518017] Call Trace:
[51679.518026]  dump_stack+0x67/0x90
[51679.518031]  register_lock_class+0x52c/0x540
[51679.518038]  ? find_held_lock+0x2d/0x90
[51679.518042]  __lock_acquire+0x68/0x1800
[51679.518047]  ? find_held_lock+0x2d/0x90
[51679.518073]  ? __i915_sw_fence_complete+0xff/0x1c0 [i915]
[51679.518079]  lock_acquire+0x90/0x170
[51679.518105]  ? i915_request_cancel_breadcrumb+0x29/0x160 [i915]
[51679.518112]  _raw_spin_lock+0x27/0x40
[51679.518138]  ? i915_request_cancel_breadcrumb+0x29/0x160 [i915]
[51679.518165]  i915_request_cancel_breadcrumb+0x29/0x160 [i915]
[51679.518199]  i915_request_retire+0x43f/0x530 [i915]
[51679.518232]  retire_requests+0x4d/0x60 [i915]
[51679.518263]  i915_retire_requests+0xdf/0x1f0 [i915]
[51679.518294]  retire_work_handler+0x4c/0x60 [i915]
[51679.518301]  process_one_work+0x22c/0x5c0
[51679.518307]  worker_thread+0x37/0x390
[51679.518311]  ? process_one_work+0x5c0/0x5c0
[51679.518316]  kthread+0x116/0x130
[51679.518320]  ? kthread_create_on_node+0x40/0x40
[51679.518325]  ret_from_fork+0x24/0x30
[51679.520177] ------------[ cut here ]------------
[51679.520189] list_del corruption, ffff88883675e2f0->next is LIST_POISON1 (dead000000000100)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111159
Fixes: 22b7a426bbe1 ("drm/i915/execlists: Preempt-to-busy")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/gt/intel_lrc.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Patch
diff mbox series

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index f95a042a92c6..884dfc1cb033 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -495,6 +495,19 @@  __unwind_incomplete_requests(struct intel_engine_cs *engine)
 			list_move(&rq->sched.link, pl);
 			active = rq;
 		} else {
+			/*
+			 * Decouple the virtual breadcrumb before moving it
+			 * back to the virtual engine -- we don't want the
+			 * request to complete in the background and try
+			 * and cancel the breadcrumb on the virtual engine
+			 * (instead of the old engine where it is linked)!
+			 */
+			if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
+				     &rq->fence.flags)) {
+				spin_lock(&rq->lock);
+				i915_request_cancel_breadcrumb(rq);
+				spin_unlock(&rq->lock);
+			}
 			rq->engine = owner;
 			owner->submit_request(rq);
 			active = NULL;