From patchwork Thu Sep 17 12:39:44 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 7206481 Return-Path: X-Original-To: patchwork-linux-nfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 7EAD9BEEC1 for ; Thu, 17 Sep 2015 12:41:54 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9BA322080E for ; Thu, 17 Sep 2015 12:41:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE3B620809 for ; Thu, 17 Sep 2015 12:41:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752248AbbIQMlv (ORCPT ); Thu, 17 Sep 2015 08:41:51 -0400 Received: from mail-yk0-f170.google.com ([209.85.160.170]:35769 "EHLO mail-yk0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751487AbbIQMjy (ORCPT ); Thu, 17 Sep 2015 08:39:54 -0400 Received: by ykdu9 with SMTP id u9so15110818ykd.2 for ; Thu, 17 Sep 2015 05:39:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=LzW73ddcDK2zLb19U3CO1cZ9rBJKy4M+Sh9wpK3nj0Y=; b=Oqox2+8sFTvNRwFkXnGO7/+mHczsVGoODbyjCeVGdurehyMi2ESIS0zj/PUvddDtet OScEjzcc07KQy4wn4AA+la7f9aqaau4DvxErpcxLlWUzba0o8r6KBGnw9Ov2ADkekitF hkl25nJMDkzg2sfjL07e+QZmcJvGB/2EJROO+mdwqZUZFu+HKukrEk1v2Itk7AHDGtOW w9j10RDmQRG0EWCpNZVcvMmVOU1G4/DSIKfC8TcqoxhK3SR0IMW/3kS/C8/eKMuJWfn9 Xyq5qI43FsDHjkMrLPjOsmulyK/w20JYBcLP/nt1D8fUOfRX5q4YFU/Gx7RiURYWODUK Pk6w== X-Gm-Message-State: ALoCoQn/jqHBBLxRyjYtkYiPuGldwKb0LwBGUYJ5GZCLLEax/PhSy4sqXEFVUPL+gz2VlIf90cNy X-Received: by 10.170.150.133 with SMTP id r127mr34082767ykc.52.1442493594141; Thu, 17 Sep 2015 05:39:54 -0700 (PDT) Received: from tlielax.poochiereds.net ([2606:a000:1105:8e:3a60:77ff:fe93:a95d]) by smtp.googlemail.com with ESMTPSA id q128sm1878652ywf.27.2015.09.17.05.39.53 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Sep 2015 05:39:53 -0700 (PDT) From: Jeff Layton X-Google-Original-From: Jeff Layton To: Al Viro Cc: bfields@fieldses.org, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/4] fs: have flush_delayed_fput flush the workqueue job Date: Thu, 17 Sep 2015 08:39:44 -0400 Message-Id: <1442493587-32499-2-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1442493587-32499-1-git-send-email-jeff.layton@primarydata.com> References: <1442493587-32499-1-git-send-email-jeff.layton@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP I think there's a potential race in flush_delayed_fput. A kthread does an fput() and that file gets added to the list and the delayed work is scheduled. More than 1 jiffy passes, and the workqueue thread picks up the work and starts running it. Then the kthread calls flush_delayed_work. It sees that the list is empty and returns immediately, even though the __fput for its file may not have run yet. Close this by making flush_delayed_fput use flush_delayed_work instead, which should immediately schedule the work to run if it's not already, and block until the workqueue job completes. Signed-off-by: Jeff Layton --- fs/file_table.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/file_table.c b/fs/file_table.c index ad17e05ebf95..52cc6803c07a 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -244,6 +244,8 @@ static void ____fput(struct callback_head *work) __fput(container_of(work, struct file, f_u.fu_rcuhead)); } +static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); + /* * If kernel thread really needs to have the final fput() it has done * to complete, call this. The only user right now is the boot - we @@ -256,11 +258,9 @@ static void ____fput(struct callback_head *work) */ void flush_delayed_fput(void) { - delayed_fput(NULL); + flush_delayed_work(&delayed_fput_work); } -static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); - void fput(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) {