From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755605AbaEPMs1 (ORCPT ); Fri, 16 May 2014 08:48:27 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:49544 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752427AbaEPMsV (ORCPT ); Fri, 16 May 2014 08:48:21 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Jeff Layton" , "J. Bruce Fields" , "Terry Barnaby" Date: Fri, 16 May 2014 13:47:20 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 05/34] locks: allow __break_lease to sleep even when break_time is 0 In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:3db0:c181:6526:5597 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.59-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jeff Layton commit f1c6bb2cb8b81013e8979806f8e15e3d53efb96d upstream. A fl->fl_break_time of 0 has a special meaning to the lease break code that basically means "never break the lease". knfsd uses this to ensure that leases don't disappear out from under it. Unfortunately, the code in __break_lease can end up passing this value to wait_event_interruptible as a timeout, which prevents it from going to sleep at all. This makes __break_lease to spin in a tight loop and causes soft lockups. Fix this by ensuring that we pass a minimum value of 1 as a timeout instead. Cc: J. Bruce Fields Reported-by: Terry Barnaby Signed-off-by: Jeff Layton Signed-off-by: Ben Hutchings --- fs/locks.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/fs/locks.c +++ b/fs/locks.c @@ -1253,11 +1253,10 @@ int __break_lease(struct inode *inode, u restart: break_time = flock->fl_break_time; - if (break_time != 0) { + if (break_time != 0) break_time -= jiffies; - if (break_time == 0) - break_time++; - } + if (break_time == 0) + break_time++; locks_insert_block(flock, new_fl); unlock_flocks(); error = wait_event_interruptible_timeout(new_fl->fl_wait,