When we close the VMA, we unbind it from the ppgtt and tear down the page directory pointing at it. That may trigger us to return WC pages back to the system, requiring conversion back to WB which itself may sleep. That makes i915_vma_close() unsuitable for use inside the RCU read lock, which we need to hold to iterate the radixtree. The fix is quite simple, we can close all the VMA as we close the ppgtt, we only need to do that instead of closing them during destruction of the LUT. v2: Order between closing the LUT and the ppgtt is important; we use the vma inside the LUT as a means of retrieving the object, and so we must clear the LUT before freeing the VMA when closing the ppgtt. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103638 Fixes: 547da76b5777 ("drm/i915: Hold rcu_read_lock when iterating over the radixtree (vma idr)") Fixes: d1b48c1e7184 ("drm/i915: Replace execbuf vma ht with an idr") Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> Cc: Matthew Auld <matthew.william.auld@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_gem_context.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index 10affb35ac56..c05c3d7d21a5 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -107,14 +107,9 @@ static void lut_close(struct i915_gem_context *ctx) rcu_read_lock(); radix_tree_for_each_slot(slot, &ctx->handles_vma, &iter, 0) { struct i915_vma *vma = rcu_dereference_raw(*slot); - struct drm_i915_gem_object *obj = vma->obj; radix_tree_iter_delete(&ctx->handles_vma, &iter, slot); - - if (!i915_vma_is_ggtt(vma)) - i915_vma_close(vma); - - __i915_gem_object_release_unless_active(obj); + __i915_gem_object_release_unless_active(vma->obj); } rcu_read_unlock(); } @@ -200,6 +195,11 @@ static void context_close(struct i915_gem_context *ctx) { i915_gem_context_set_closed(ctx); + /* + * The LUT uses the VMA as a backpointer to unref the object, + * so we need to clear the LUT before we close all the VMA (inside + * the ppgtt). + */ lut_close(ctx); if (ctx->ppgtt) i915_ppgtt_close(&ctx->ppgtt->base); -- 2.15.0 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
