With a view to removing the nasty recursion on struct_mutex (which allows us to wait upon it while also servicing GPU resets and the shrinker), explicitly track any mutex which might be used inside i915_reset() and warn if we hit a potential inversion where we are holding the mutex and may need to reset (e.g. waiting on the GPU).
A simple premise we enforce is that we cannot wait on the GPU while holding any mutex required to perform a GPU reset, and by extension this means we cannot shrink while holding that mutex either (as we must be able to perform a GPU reset to advance the shrinker). Signed-off-by: Chris Wilson <[email protected]> --- drivers/gpu/drm/i915/i915_drv.c | 33 ++++++++++++++++++- drivers/gpu/drm/i915/i915_drv.h | 3 ++ drivers/gpu/drm/i915/i915_gpu_error.h | 2 ++ drivers/gpu/drm/i915/i915_request.c | 12 +++++-- .../gpu/drm/i915/selftests/mock_gem_device.c | 2 ++ 5 files changed, 49 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 3834bd758a2e..f8b69aff3d45 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -35,6 +35,7 @@ #include <linux/pm.h> #include <linux/pm_runtime.h> #include <linux/pnp.h> +#include <linux/sched/mm.h> #include <linux/slab.h> #include <linux/vgaarb.h> #include <linux/vga_switcheroo.h> @@ -864,6 +865,19 @@ static void intel_detect_preproduction_hw(struct drm_i915_private *dev_priv) } } +static void i915_reset_lockdep_init(struct i915_gpu_error *error) +{ + static struct lock_class_key reset_key; + + lockdep_init_map(&error->lockdep, "i915.reset", &reset_key, 0); + + /* We must be able to reset while stuck in the shrinker */ + fs_reclaim_acquire(GFP_KERNEL); + lock_map_acquire(&error->lockdep); + lock_map_release(&error->lockdep); + fs_reclaim_release(GFP_KERNEL); +} + /** * i915_driver_init_early - setup state not requiring device access * @dev_priv: device private @@ -894,11 +908,14 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv, BUILD_BUG_ON(INTEL_MAX_PLATFORMS > sizeof(device_info->platform_mask) * BITS_PER_BYTE); BUG_ON(device_info->gen > sizeof(device_info->gen_mask) * BITS_PER_BYTE); + spin_lock_init(&dev_priv->irq_lock); - spin_lock_init(&dev_priv->gpu_error.lock); mutex_init(&dev_priv->backlight_lock); spin_lock_init(&dev_priv->uncore.lock); + spin_lock_init(&dev_priv->gpu_error.lock); + i915_reset_lockdep_init(&dev_priv->gpu_error); + mutex_init(&dev_priv->sb_lock); mutex_init(&dev_priv->modeset_restore_lock); mutex_init(&dev_priv->av_mutex); @@ -1917,6 +1934,8 @@ void i915_reset(struct drm_i915_private *i915, if (!test_bit(I915_RESET_HANDOFF, &error->flags)) return; + lock_map_acquire(&error->lockdep); + /* Clear any previous failed attempts at recovery. Time to try again. */ if (!i915_gem_unset_wedged(i915)) goto wakeup; @@ -1990,6 +2009,7 @@ void i915_reset(struct drm_i915_private *i915, enable_irq(i915->drm.irq); wakeup: + lock_map_release(&error->lockdep); clear_bit(I915_RESET_HANDOFF, &error->flags); wake_up_bit(&error->flags, I915_RESET_HANDOFF); return; @@ -2014,6 +2034,17 @@ void i915_reset(struct drm_i915_private *i915, goto finish; } +void i915_reset_taints_mutex(struct drm_i915_private *i915, struct mutex *mutex) +{ + if (!IS_ENABLED(CONFIG_LOCKDEP)) + return; + + lock_map_acquire(&i915->gpu_error.lockdep); + mutex_lock(mutex); + mutex_unlock(mutex); + lock_map_release(&i915->gpu_error.lockdep); +} + static inline int intel_gt_reset_engine(struct drm_i915_private *dev_priv, struct intel_engine_cs *engine) { diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 4fb937399440..006000bfffcf 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2719,6 +2719,9 @@ extern void i915_reset(struct drm_i915_private *i915, extern int i915_reset_engine(struct intel_engine_cs *engine, const char *reason); +extern void i915_reset_taints_mutex(struct drm_i915_private *i915, + struct mutex *mutex); + extern bool intel_has_reset_engine(struct drm_i915_private *dev_priv); extern int intel_reset_guc(struct drm_i915_private *dev_priv); extern int intel_guc_reset_engine(struct intel_guc *guc, diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h index f893a4e8b783..78521b10d9e5 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.h +++ b/drivers/gpu/drm/i915/i915_gpu_error.h @@ -293,6 +293,8 @@ struct i915_gpu_error { /* For missed irq/seqno simulation. */ unsigned long test_irq_rings; + + struct lockdep_map lockdep; }; struct drm_i915_error_state_buf { diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 5c2c93cbab12..8216639697a4 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -1253,8 +1253,12 @@ static bool __i915_wait_request_check_and_reset(struct i915_request *request) if (likely(!i915_reset_handoff(error))) return false; + lock_map_release(&error->lockdep); + __set_current_state(TASK_RUNNING); i915_reset(request->i915, error->stalled_mask, error->reason); + + lock_map_acquire_read(&error->lockdep); return true; } @@ -1305,8 +1309,10 @@ long i915_request_wait(struct i915_request *rq, trace_i915_request_wait_begin(rq, flags); add_wait_queue(&rq->execute, &exec); - if (flags & I915_WAIT_LOCKED) + if (flags & I915_WAIT_LOCKED) { + lock_map_acquire_read(&rq->i915->gpu_error.lockdep); add_wait_queue(errq, &reset); + } intel_wait_init(&wait); @@ -1409,8 +1415,10 @@ long i915_request_wait(struct i915_request *rq, intel_engine_remove_wait(rq->engine, &wait); complete: __set_current_state(TASK_RUNNING); - if (flags & I915_WAIT_LOCKED) + if (flags & I915_WAIT_LOCKED) { + lock_map_release(&rq->i915->gpu_error.lockdep); remove_wait_queue(errq, &reset); + } remove_wait_queue(&rq->execute, &exec); trace_i915_request_wait_end(rq); diff --git a/drivers/gpu/drm/i915/selftests/mock_gem_device.c b/drivers/gpu/drm/i915/selftests/mock_gem_device.c index 43ed8b28aeaa..d14830a3794c 100644 --- a/drivers/gpu/drm/i915/selftests/mock_gem_device.c +++ b/drivers/gpu/drm/i915/selftests/mock_gem_device.c @@ -135,6 +135,7 @@ static struct dev_pm_domain pm_domain = { struct drm_i915_private *mock_gem_device(void) { + static struct lock_class_key reset_key; struct drm_i915_private *i915; struct pci_dev *pdev; int err; @@ -184,6 +185,7 @@ struct drm_i915_private *mock_gem_device(void) mock_uncore_init(i915); i915_gem_init__mm(i915); + lockdep_init_map(&i915->gpu_error.lockdep, "i915.reset", &reset_key, 0); init_waitqueue_head(&i915->gpu_error.wait_queue); init_waitqueue_head(&i915->gpu_error.reset_queue); -- 2.18.0 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
