From 312c4ba1bb71d666f924f84afd5bdc775b71278f Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 8 Feb 2019 13:47:04 +0000 Subject: [PATCH] drm/i915: Protect i915_active iterators from the shrinker If we allocate while iterating the rbtree of active nodes, we may hit the shrinker and so retire the i915_active, reaping the rbtree. Modifying the rbtree as we iterate is not good behaviour, so acquire the i915_active first to keep the tree intact whenever we allocate. Fixes: a42375af0a30 ("drm/i915: Release the active tracker tree upon idling") Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Cc: Joonas Lahtinen Link: https://patchwork.freedesktop.org/patch/msgid/20190208134704.23039-1-chris@chris-wilson.co.uk Reviewed-by: Tvrtko Ursulin --- drivers/gpu/drm/i915/i915_active.c | 36 +++++++++++++++++++++--------- 1 file changed, 25 insertions(+), 11 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c index 215b6ff8aa73..db7bb5bd5add 100644 --- a/drivers/gpu/drm/i915/i915_active.c +++ b/drivers/gpu/drm/i915/i915_active.c @@ -163,17 +163,25 @@ int i915_active_ref(struct i915_active *ref, struct i915_request *rq) { struct i915_active_request *active; + int err = 0; + + /* Prevent reaping in case we malloc/wait while building the tree */ + i915_active_acquire(ref); active = active_instance(ref, timeline); - if (IS_ERR(active)) - return PTR_ERR(active); + if (IS_ERR(active)) { + err = PTR_ERR(active); + goto out; + } if (!i915_active_request_isset(active)) ref->count++; __i915_active_request_set(active, rq); GEM_BUG_ON(!ref->count); - return 0; +out: + i915_active_release(ref); + return err; } bool i915_active_acquire(struct i915_active *ref) @@ -223,19 +231,25 @@ int i915_request_await_active_request(struct i915_request *rq, int i915_request_await_active(struct i915_request *rq, struct i915_active *ref) { struct active_node *it, *n; - int ret; + int err = 0; - ret = i915_request_await_active_request(rq, &ref->last); - if (ret) - return ret; + /* await allocates and so we need to avoid hitting the shrinker */ + if (i915_active_acquire(ref)) + goto out; /* was idle */ + + err = i915_request_await_active_request(rq, &ref->last); + if (err) + goto out; rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) { - ret = i915_request_await_active_request(rq, &it->base); - if (ret) - return ret; + err = i915_request_await_active_request(rq, &it->base); + if (err) + goto out; } - return 0; +out: + i915_active_release(ref); + return err; } #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM) -- 2.30.2