From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757082Ab1EaPhu (ORCPT ); Tue, 31 May 2011 11:37:50 -0400 Received: from mail-pw0-f46.google.com ([209.85.160.46]:38216 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751038Ab1EaPht (ORCPT ); Tue, 31 May 2011 11:37:49 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=DN8vo8Knkt5EilwLiMo1k3Ojg2goDY4zqcmGXCsV2BGLvd5kY2VGEAMXTdBMq5HnQG 4wEYULyqAxLYQVqZ5iEFjpoxMGDWCTpdHpp3RueFsVJ6WRlKvBfU8hDknRsg45nyq2jm C0S8N+Xjw+bsN5X3LIh5ZWq2DgL4v/5esTyTg= Date: Wed, 1 Jun 2011 00:37:44 +0900 From: Tejun Heo To: David Miller Cc: linux-kernel@vger.kernel.org Subject: Re: blkdev_get() change causes OOPS... Message-ID: <20110531153744.GB9048@mtj.dyndns.org> References: <20110530.223506.424661345.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110530.223506.424661345.davem@davemloft.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 30, 2011 at 10:35:07PM -0700, David Miller wrote: > > I don't think whole->bd_disk is guaranteed to be non-NULL where you're > dereferencing it in blkdev_get() after commit > d4dc210f69bcb0b4bef5a83b1c323817be89bad1 ("block: don't block events > on excl write for non-optical devices") Ah... right, it's there if open succeeded. I should have put the test after !res test. Does the following patch fix the problem? Thanks. diff --git a/fs/block_dev.c b/fs/block_dev.c index 1f2b199..1a2421f 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1272,8 +1272,8 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) * individual writeable reference is too fragile given the * way @mode is used in blkdev_get/put(). */ - if ((disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE) && - !res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) { + if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder && + (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { bdev->bd_write_holder = true; disk_block_events(disk); }