6.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Rob Clark robdclark@chromium.org
[ Upstream commit 3136a0f83519076edfbc14be65f286785434189a ]
For normal GPU devfreq, we need to acquire the GMU lock while already holding devfreq locks. But in the teardown path, we were calling dev_pm_domain_detach() while already holding the GMU lock, resulting in this lockdep splat:
====================================================== WARNING: possible circular locking dependency detected 6.4.3-debug+ #3 Not tainted ------------------------------------------------------ ring0/391 is trying to acquire lock: ffffff80a025c078 (&devfreq->lock){+.+.}-{3:3}, at: qos_notifier_call+0x30/0x74
but task is already holding lock: ffffff809b8c1ce8 (&(c->notifiers)->rwsem){++++}-{3:3}, at: blocking_notifier_call_chain+0x34/0x78
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (&(c->notifiers)->rwsem){++++}-{3:3}: down_write+0x58/0x74 __blocking_notifier_chain_register+0x64/0x84 blocking_notifier_chain_register+0x1c/0x28 freq_qos_add_notifier+0x5c/0x7c dev_pm_qos_add_notifier+0xd4/0xf0 devfreq_add_device+0x42c/0x560 devm_devfreq_add_device+0x6c/0xb8 msm_devfreq_init+0xa8/0x16c [msm] msm_gpu_init+0x368/0x54c [msm] adreno_gpu_init+0x248/0x2b0 [msm] a6xx_gpu_init+0x2d0/0x384 [msm] adreno_bind+0x264/0x2bc [msm] component_bind_all+0x124/0x1f4 msm_drm_bind+0x2d0/0x5f4 [msm] try_to_bring_up_aggregate_device+0x88/0x1a4 __component_add+0xd4/0x128 component_add+0x1c/0x28 dp_display_probe+0x37c/0x3c0 [msm] platform_probe+0x70/0xc0 really_probe+0x148/0x280 __driver_probe_device+0xfc/0x114 driver_probe_device+0x44/0x100 __device_attach_driver+0x64/0xdc bus_for_each_drv+0xb0/0xd8 __device_attach+0xe4/0x140 device_initial_probe+0x1c/0x28 bus_probe_device+0x44/0xb0 deferred_probe_work_func+0xb0/0xc8 process_one_work+0x288/0x3d8 worker_thread+0x1f0/0x260 kthread+0xf0/0x100 ret_from_fork+0x10/0x20
-> #3 (dev_pm_qos_mtx){+.+.}-{3:3}: __mutex_lock+0xc8/0x388 mutex_lock_nested+0x2c/0x38 dev_pm_qos_remove_notifier+0x3c/0xc8 genpd_remove_device+0x40/0x11c genpd_dev_pm_detach+0x88/0x130 dev_pm_domain_detach+0x2c/0x3c a6xx_gmu_remove+0x44/0xdc [msm] a6xx_destroy+0x7c/0xa4 [msm] adreno_unbind+0x50/0x64 [msm] component_unbind+0x44/0x64 component_unbind_all+0xb4/0xbc msm_drm_uninit.isra.0+0x124/0x17c [msm] msm_drm_bind+0x340/0x5f4 [msm] try_to_bring_up_aggregate_device+0x88/0x1a4 __component_add+0xd4/0x128 component_add+0x1c/0x28 dp_display_probe+0x37c/0x3c0 [msm] platform_probe+0x70/0xc0 really_probe+0x148/0x280 __driver_probe_device+0xfc/0x114 driver_probe_device+0x44/0x100 __device_attach_driver+0x64/0xdc bus_for_each_drv+0xb0/0xd8 __device_attach+0xe4/0x140 device_initial_probe+0x1c/0x28 bus_probe_device+0x44/0xb0 deferred_probe_work_func+0xb0/0xc8 process_one_work+0x288/0x3d8 worker_thread+0x1f0/0x260 kthread+0xf0/0x100 ret_from_fork+0x10/0x20
-> #2 (&a6xx_gpu->gmu.lock){+.+.}-{3:3}: __mutex_lock+0xc8/0x388 mutex_lock_nested+0x2c/0x38 a6xx_gpu_set_freq+0x38/0x64 [msm] msm_devfreq_target+0x170/0x18c [msm] devfreq_set_target+0x90/0x1e4 devfreq_update_target+0xb4/0xf0 update_devfreq+0x1c/0x28 devfreq_monitor+0x3c/0x10c process_one_work+0x288/0x3d8 worker_thread+0x1f0/0x260 kthread+0xf0/0x100 ret_from_fork+0x10/0x20
-> #1 (&df->lock){+.+.}-{3:3}: __mutex_lock+0xc8/0x388 mutex_lock_nested+0x2c/0x38 msm_devfreq_get_dev_status+0x4c/0x104 [msm] devfreq_simple_ondemand_func+0x5c/0x128 devfreq_update_target+0x68/0xf0 update_devfreq+0x1c/0x28 devfreq_monitor+0x3c/0x10c process_one_work+0x288/0x3d8 worker_thread+0x1f0/0x260 kthread+0xf0/0x100 ret_from_fork+0x10/0x20
-> #0 (&devfreq->lock){+.+.}-{3:3}: __lock_acquire+0xdf8/0x109c lock_acquire+0x234/0x284 __mutex_lock+0xc8/0x388 mutex_lock_nested+0x2c/0x38 qos_notifier_call+0x30/0x74 qos_min_notifier_call+0x1c/0x28 notifier_call_chain+0xf4/0x114 blocking_notifier_call_chain+0x4c/0x78 pm_qos_update_target+0x184/0x190 freq_qos_apply+0x4c/0x64 apply_constraint+0xf8/0xfc __dev_pm_qos_update_request+0x138/0x164 dev_pm_qos_update_request+0x44/0x68 msm_devfreq_boost+0x40/0x70 [msm] msm_devfreq_active+0xc0/0xf0 [msm] msm_gpu_submit+0xc8/0x12c [msm] msm_job_run+0x88/0x128 [msm] drm_sched_main+0x240/0x324 [gpu_sched] kthread+0xf0/0x100 ret_from_fork+0x10/0x20
other info that might help us debug this: Chain exists of: &devfreq->lock --> dev_pm_qos_mtx --> &(c->notifiers)->rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&(c->notifiers)->rwsem); lock(dev_pm_qos_mtx); lock(&(c->notifiers)->rwsem); lock(&devfreq->lock);
*** DEADLOCK *** 4 locks held by ring0/391: #0: ffffff809c811170 (&gpu->lock){+.+.}-{3:3}, at: msm_job_run+0x7c/0x128 [msm] #1: ffffff809c811208 (&gpu->active_lock){+.+.}-{3:3}, at: msm_gpu_submit+0xa8/0x12c [msm] #2: ffffffecbbb46600 (dev_pm_qos_mtx){+.+.}-{3:3}, at: dev_pm_qos_update_request+0x38/0x68 #3: ffffff809b8c1ce8 (&(c->notifiers)->rwsem){++++}-{3:3}, at: blocking_notifier_call_chain+0x34/0x78
stack backtrace: CPU: 6 PID: 391 Comm: ring0 Not tainted 6.4.3debug+ #3 Hardware name: Google Villager (rev1+) with LTE (DT) Call trace: dump_backtrace+0xb4/0xf0 show_stack+0x20/0x30 dump_stack_lvl+0x60/0x84 dump_stack+0x18/0x24 print_circular_bug+0x1cc/0x234 check_noncircular+0x78/0xac __lock_acquire+0xdf8/0x109c lock_acquire+0x234/0x284 __mutex_lock+0xc8/0x388 mutex_lock_nested+0x2c/0x38 qos_notifier_call+0x30/0x74 qos_min_notifier_call+0x1c/0x28 notifier_call_chain+0xf4/0x114 blocking_notifier_call_chain+0x4c/0x78 pm_qos_update_target+0x184/0x190 freq_qos_apply+0x4c/0x64 apply_constraint+0xf8/0xfc __dev_pm_qos_update_request+0x138/0x164 dev_pm_qos_update_request+0x44/0x68 msm_devfreq_boost+0x40/0x70 [msm] msm_devfreq_active+0xc0/0xf0 [msm] msm_gpu_submit+0xc8/0x12c [msm] msm_job_run+0x88/0x128 [msm] drm_sched_main+0x240/0x324 [gpu_sched] kthread+0xf0/0x100 ret_from_fork+0x10/0x20
Fix this by only synchronizing access to gmu->initialized.
Fixes: 4cd15a3e8b36 ("drm/msm/a6xx: Make GPU destroy a bit safer") Cc: Douglas Anderson dianders@chromium.org Signed-off-by: Rob Clark robdclark@chromium.org Reviewed-by: Douglas Anderson dianders@chromium.org Patchwork: https://patchwork.freedesktop.org/patch/551171/ Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 11 ++++++++--- drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 2 -- 2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c index 8914992378f21..1ff2a71e1aea5 100644 --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c @@ -1472,8 +1472,15 @@ void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu) struct a6xx_gmu *gmu = &a6xx_gpu->gmu; struct platform_device *pdev = to_platform_device(gmu->dev);
- if (!gmu->initialized) + mutex_lock(&gmu->lock); + if (!gmu->initialized) { + mutex_unlock(&gmu->lock); return; + } + + gmu->initialized = false; + + mutex_unlock(&gmu->lock);
pm_runtime_force_suspend(gmu->dev);
@@ -1501,8 +1508,6 @@ void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu)
/* Drop reference taken in of_find_device_by_node */ put_device(gmu->dev); - - gmu->initialized = false; }
static int cxpd_notifier_cb(struct notifier_block *nb, diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c index 411b7a5fa2f32..bdda1a6336543 100644 --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c @@ -1697,9 +1697,7 @@ static void a6xx_destroy(struct msm_gpu *gpu)
a6xx_llc_slices_destroy(a6xx_gpu);
- mutex_lock(&a6xx_gpu->gmu.lock); a6xx_gmu_remove(a6xx_gpu); - mutex_unlock(&a6xx_gpu->gmu.lock);
adreno_gpu_cleanup(adreno_gpu);