| Message ID | 1494411651-10507-1-git-send-email-joonas.lahtinen@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c index 0e7352d..e1868ed 100644 --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c @@ -59,9 +59,6 @@ static void shrinker_unlock(struct drm_i915_private *dev_priv, bool unlock) return; mutex_unlock(&dev_priv->drm.struct_mutex); - - /* expedite the RCU grace period to free some request slabs */ - synchronize_rcu_expedited(); } static bool any_vma_pinned(struct drm_i915_gem_object *obj)
Due to the complex dependencies between workqueues and RCU, which are not easily detected by lockdep, do not synchronize RCU during shrinking. On low-on-memory systems (mem=1G for example), the RCU sync leads to all system workqueus freezing and unrelated lockdep splats are displayed according to reports. GIT bisecting done by J. R. Okajima points to the commit where RCU syncing was extended. RCU sync gains us very little benefit in real life scenarios where the amount of memory used by object backing storage is dominant over the metadata under RCU, so drop it altogether. " Yeeeaah, if core could just, go ahead and reclaim RCU queues, that'd be great. " - Chris Wilson, 2016 (0eafec6d3244) v2: More information to commit message. Fixes: c053b5a506d3 ("drm/i915: Don't call synchronize_rcu_expedited under struct_mutex") Suggested-by: Chris Wilson <chris@chris-wilson.co.uk> Reported-by: J. R. Okajima <hooanon05g@gmail.com> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Tested-by: Hugh Dickins <hughd@google.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: J. R. Okajima <hooanon05g@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: <stable@vger.kernel.org> # v4.11+ --- drivers/gpu/drm/i915/i915_gem_shrinker.c | 3 --- 1 file changed, 3 deletions(-)