From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1165766AbdD3GIP (ORCPT ); Sun, 30 Apr 2017 02:08:15 -0400 Received: from mail02-md.ns.itscom.net ([175.177.155.112]:42099 "EHLO mail02-md.ns.itscom.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1165736AbdD3GIJ (ORCPT ); Sun, 30 Apr 2017 02:08:09 -0400 From: "J. R. Okajima" To: joonas.lahtinen@linux.intel.com cc: aarcange@redhat.com, chris@chris-wilson.co.uk, daniel.vetter@ffwll.ch, jani.nikula@intel.com, linux-kernel@vger.kernel.org Subject: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers Date: Sun, 30 Apr 2017 15:07:58 +0900 Message-ID: <7743.1493532478@jrobl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Since v4.11-rc7 I can see the workqueue stops on my development/test system. Git-bisecting tells me the suspicious commit is c053b5a 2017-04-11 drm/i915: Don't call synchronize_rcu_expedited under struct_mutex I am not sure whether this is the real cause or not of my problem, but I have a question. By the commit, the shrinker handlers ->scan_objects() and ->count_objects() both calls synchronize_rcu_expedited() unconditionally. Is it a legal RCU bahavour? I know dev->struct_mutex is unlocked now, but before the commit, these two handlers were not calling synchronize_rcu_expedited(). J. R. Okajima