From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756200AbbJ1U7V (ORCPT ); Wed, 28 Oct 2015 16:59:21 -0400 Received: from terminus.zytor.com ([198.137.202.10]:48028 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753688AbbJ1U7T (ORCPT ); Wed, 28 Oct 2015 16:59:19 -0400 Date: Wed, 28 Oct 2015 13:58:16 -0700 From: tip-bot for Tejun Heo Message-ID: Cc: edumazet@google.com, dipankar@in.ibm.com, torvalds@linux-foundation.org, jiangshanlai@gmail.com, bobby.prani@gmail.com, rostedt@goodmis.org, peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@kernel.org, mathieu.desnoyers@efficios.com, dhowells@redhat.com, hpa@zytor.com, dvhart@linux.intel.com, tj@kernel.org, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, josh@joshtriplett.org, fweisbec@gmail.com, oleg@redhat.com, patrick.marlier@gmail.com Reply-To: peterz@infradead.org, rostedt@goodmis.org, bobby.prani@gmail.com, jiangshanlai@gmail.com, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, mingo@kernel.org, dhowells@redhat.com, edumazet@google.com, torvalds@linux-foundation.org, dipankar@in.ibm.com, oleg@redhat.com, patrick.marlier@gmail.com, dvhart@linux.intel.com, hpa@zytor.com, tglx@linutronix.de, paulmck@linux.vnet.ibm.com, tj@kernel.org, josh@joshtriplett.org, fweisbec@gmail.com In-Reply-To: <20151027051939.GA19355@mtj.duckdns.org> References: <20151027051939.GA19355@mtj.duckdns.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/rcu] fs/writeback, rcu: Don't use list_entry_rcu() for pointer offsetting in bdi_split_work_to_wbs() Git-Commit-ID: b33e18f61bd18227a456016a77b1a968f5bc1d65 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b33e18f61bd18227a456016a77b1a968f5bc1d65 Gitweb: http://git.kernel.org/tip/b33e18f61bd18227a456016a77b1a968f5bc1d65 Author: Tejun Heo AuthorDate: Tue, 27 Oct 2015 14:19:39 +0900 Committer: Ingo Molnar CommitDate: Wed, 28 Oct 2015 13:17:30 +0100 fs/writeback, rcu: Don't use list_entry_rcu() for pointer offsetting in bdi_split_work_to_wbs() bdi_split_work_to_wbs() uses list_for_each_entry_rcu_continue() to walk @bdi->wb_list. To set up the initial iteration condition, it uses list_entry_rcu() to calculate the entry pointer corresponding to the list head; however, this isn't an actual RCU dereference and using list_entry_rcu() for it ended up breaking a proposed list_entry_rcu() change because it was feeding an non-lvalue pointer into the macro. Don't use the RCU variant for simple pointer offsetting. Use list_entry() instead. Reported-by: Ingo Molnar Signed-off-by: Tejun Heo Cc: Darren Hart Cc: David Howells Cc: Dipankar Sarma Cc: Eric Dumazet Cc: Frederic Weisbecker Cc: Josh Triplett Cc: Lai Jiangshan Cc: Linus Torvalds Cc: Mathieu Desnoyers Cc: Oleg Nesterov Cc: Patrick Marlier Cc: Paul McKenney Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Cc: pranith kumar Link: http://lkml.kernel.org/r/20151027051939.GA19355@mtj.duckdns.org Signed-off-by: Ingo Molnar --- fs/fs-writeback.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 29e4599..7378169 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -779,8 +779,8 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, bool skip_if_busy) { struct bdi_writeback *last_wb = NULL; - struct bdi_writeback *wb = list_entry_rcu(&bdi->wb_list, - struct bdi_writeback, bdi_node); + struct bdi_writeback *wb = list_entry(&bdi->wb_list, + struct bdi_writeback, bdi_node); might_sleep(); restart: