etnaviv: Possible circular lockingon i.MX6QP

[Fabio Estevam <festevam@xxxxxxxxx>]

Hi,

On a imx6qp-wandboard I get the warning below about a possible
circular locking dependency running 5.1.9 built from
imx_v6_v7_defconfig.

Such warning does not happen on the imx6q or imx6solo variants of
wandboard though.

Any ideas?

Thanks,

Fabio Estevam

** (matchbox-panel:708): WARNING **: Failed to load applet "battery"
(/usr/lib/matchbox-panel/libbattery.so: cannot open shared object
file: No such file or directory).
matchbox-wm: X error warning (0xe00003): BadWindow (invalid Window
parameter) (opcode: 12)
etnaviv-gpu 134000.gpu: MMU fault status 0x00000001
etnaviv-gpu 134000.gpu: MMU 0 fault addr 0x0805ffc0

======================================================
WARNING: possible circular locking dependency detected
5.1.9 #58 Not tainted
------------------------------------------------------
kworker/0:1/29 is trying to acquire lock:
(ptrval) (&(&gpu->fence_spinlock)->rlock){-...}, at:
dma_fence_remove_callback+0x14/0x50

but task is already holding lock:
(ptrval) (&(&sched->job_list_lock)->rlock){-...}, at: drm_sched_stop+0x1c/0x124

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&(&sched->job_list_lock)->rlock){-...}:
       drm_sched_process_job+0x5c/0x1c8
       dma_fence_signal+0xdc/0x1d4
       irq_handler+0xd0/0x1e0
       __handle_irq_event_percpu+0x48/0x360
       handle_irq_event_percpu+0x28/0x7c
       handle_irq_event+0x38/0x5c
       handle_fasteoi_irq+0xc0/0x17c
       generic_handle_irq+0x20/0x34
       __handle_domain_irq+0x64/0xe0
       gic_handle_irq+0x4c/0xa8
       __irq_svc+0x70/0x98
       cpuidle_enter_state+0x168/0x5a4
       cpuidle_enter_state+0x168/0x5a4
       do_idle+0x220/0x2c0
       cpu_startup_entry+0x18/0x20
       start_kernel+0x3e4/0x498

-> #0 (&(&gpu->fence_spinlock)->rlock){-...}:
       _raw_spin_lock_irqsave+0x38/0x4c
       dma_fence_remove_callback+0x14/0x50
       drm_sched_stop+0x98/0x124
       etnaviv_sched_timedout_job+0x7c/0xb4
       drm_sched_job_timedout+0x34/0x5c
       process_one_work+0x2ac/0x704
       worker_thread+0x2c/0x574
       kthread+0x134/0x148
       ret_from_fork+0x14/0x20
         (null)

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&(&sched->job_list_lock)->rlock);
                               lock(&(&gpu->fence_spinlock)->rlock);
                               lock(&(&sched->job_list_lock)->rlock);
  lock(&(&gpu->fence_spinlock)->rlock);

 *** DEADLOCK ***

3 locks held by kworker/0:1/29:
 #0: (ptrval) ((wq_completion)events){+.+.}, at: process_one_work+0x1f4/0x704
 #1: (ptrval) ((work_completion)(&(&sched->work_tdr)->work)){+.+.},
at: process_one_work+0x1f4/0x704
 #2: (ptrval) (&(&sched->job_list_lock)->rlock){-...}, at:
drm_sched_stop+0x1c/0x124

stack backtrace:
CPU: 0 PID: 29 Comm: kworker/0:1 Not tainted 5.1.9 #58
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
Workqueue: events drm_sched_job_timedout
[<c0112748>] (unwind_backtrace) from [<c010cfbc>] (show_stack+0x10/0x14)
[<c010cfbc>] (show_stack) from [<c0bd31ec>] (dump_stack+0xd8/0x110)
[<c0bd31ec>] (dump_stack) from [<c017a22c>]
(print_circular_bug.constprop.19+0x1bc/0x2f0)
[<c017a22c>] (print_circular_bug.constprop.19) from [<c017d408>]
(__lock_acquire+0x1778/0x1f38)
[<c017d408>] (__lock_acquire) from [<c017e3a4>] (lock_acquire+0xcc/0x1e8)
[<c017e3a4>] (lock_acquire) from [<c0bf4134>] (_raw_spin_lock_irqsave+0x38/0x4c)
[<c0bf4134>] (_raw_spin_lock_irqsave) from [<c0692710>]
(dma_fence_remove_callback+0x14/0x50)
[<c0692710>] (dma_fence_remove_callback) from [<c05d25b4>]
(drm_sched_stop+0x98/0x124)
[<c05d25b4>] (drm_sched_stop) from [<c064a3e8>]
(etnaviv_sched_timedout_job+0x7c/0xb4)
[<c064a3e8>] (etnaviv_sched_timedout_job) from [<c05d2964>]
(drm_sched_job_timedout+0x34/0x5c)
[<c05d2964>] (drm_sched_job_timedout) from [<c01468ec>]
(process_one_work+0x2ac/0x704)
[<c01468ec>] (process_one_work) from [<c0146d70>] (worker_thread+0x2c/0x574)
[<c0146d70>] (worker_thread) from [<c014cd88>] (kthread+0x134/0x148)
[<c014cd88>] (kthread) from [<c01010b4>] (ret_from_fork+0x14/0x20)
Exception stack(0xe81f7fb0 to 0xe81f7ff8)
7fa0:                                     00000000 00000000 00000000 00000000
7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
7fe0: 00000000 00000000 00000000 00000000 00000013 00000000
etnaviv-gpu 134000.gpu: recover hung GPU!
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