drm/i915: Remove waiting & retiring from shrinker paths

i915_gem_wait_for_idle() and i915_retire_requests() introduce a
dependency on the timeline->mutex. This is problematic as we want to
later perform allocations underneath i915_active.mutex, forming a link
between the shrinker, the timeline and active mutexes. Nip this cycle in
the bud by removing the acquisition of the timeline mutex (i.e.
retiring) from inside the shrinker.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190621183801.23252-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
index 3a926a8..1bbc690 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
@@ -169,7 +169,6 @@ i915_gem_shrink(struct drm_i915_private *i915,
         */
 
        trace_i915_gem_shrink(i915, target, shrink);
-       i915_retire_requests(i915);
 
        /*
         * Unbinding of objects will require HW access; Let us not wake the
@@ -269,8 +268,6 @@ i915_gem_shrink(struct drm_i915_private *i915,
        if (shrink & I915_SHRINK_BOUND)
                intel_runtime_pm_put(&i915->runtime_pm, wakeref);
 
-       i915_retire_requests(i915);
-
        shrinker_unlock(i915, unlock);
 
        if (nr_scanned)
@@ -427,12 +424,6 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
        if (!shrinker_lock(i915, 0, &unlock))
                return NOTIFY_DONE;
 
-       /* Force everything onto the inactive lists */
-       if (i915_gem_wait_for_idle(i915,
-                                  I915_WAIT_LOCKED,
-                                  MAX_SCHEDULE_TIMEOUT))
-               goto out;
-
        with_intel_runtime_pm(&i915->runtime_pm, wakeref)
                freed_pages += i915_gem_shrink(i915, -1UL, NULL,
                                               I915_SHRINK_BOUND |
@@ -455,7 +446,6 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
        }
        mutex_unlock(&i915->ggtt.vm.mutex);
 
-out:
        shrinker_unlock(i915, unlock);
 
        *(unsigned long *)ptr += freed_pages;

diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
index 167c4a5..53c81b5 100644 (file)
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
@@ -427,6 +427,9 @@ create_test_object(struct i915_gem_context *ctx,
        u64 size;
        int err;
 
+       /* Keep in GEM's good graces */
+       i915_retire_requests(ctx->i915);
+
        size = min(vm->total / 2, 1024ull * DW_PER_PAGE * PAGE_SIZE);
        size = round_down(size, DW_PER_PAGE * PAGE_SIZE);
 

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_types.h b/drivers/gpu/drm/i915/gt/intel_gt_types.h
index 722506b..c03e566 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_gt_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_types.h
@@ -26,7 +26,7 @@ struct intel_gt {
        struct i915_ggtt *ggtt;
 
        struct intel_gt_timelines {
-               struct mutex mutex; /* protects list, tainted by GPU */
+               struct mutex mutex; /* protects list */
                struct list_head active_list;
 
                /* Pack multiple timelines' seqnos into the same page */

diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c
index d6accef..44273b7 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_timeline.c
+++ b/drivers/gpu/drm/i915/gt/intel_timeline.c
@@ -268,9 +268,6 @@ static void timelines_init(struct intel_gt *gt)
 
        spin_lock_init(&timelines->hwsp_lock);
        INIT_LIST_HEAD(&timelines->hwsp_free_list);
-
-       /* via i915_gem_wait_for_idle() */
-       i915_gem_shrinker_taints_mutex(gt->i915, &timelines->mutex);
 }
 
 void intel_timelines_init(struct drm_i915_private *i915)