From mboxrd@z Thu Jan 1 00:00:00 1970 From: john stultz Subject: Re: 2.6.33.3-rt19 kernel BUG's Date: Fri, 07 May 2010 17:39:13 -0700 Message-ID: <1273279153.2776.7.camel@localhost.localdomain> References: <1273197218.6768.10.camel@localhost.localdomain> <1273275821.2776.3.camel@localhost.localdomain> <1273276725.17045.4.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Thomas Gleixner , LKML , rt-users , Steven Rostedt , Nick Piggin To: Fernando Lopez-Lezcano Return-path: Received: from e7.ny.us.ibm.com ([32.97.182.137]:49012 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750956Ab0EHAjT (ORCPT ); Fri, 7 May 2010 20:39:19 -0400 In-Reply-To: <1273276725.17045.4.camel@localhost.localdomain> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Fri, 2010-05-07 at 23:58 +0000, Fernando Lopez-Lezcano wrote: > On Fri, 2010-05-07 at 16:43 -0700, john stultz wrote: > > On Fri, 2010-05-07 at 12:41 +0200, Thomas Gleixner wrote: > > > On Thu, 6 May 2010, Fernando Lopez-Lezcano wrote: > > > > > > CC'ed John and Nick > > > > > > > See below... just trying to boot (quad core desktop machine). > > > > Ok. Got this to reproduce. Will hopefully have a fix for your soon. > > > > Thanks for the bug report! > > Thanks for looking at it! It had been a while since I had problems with > rt so I could not understand why I could not login :-) Bah! I should have caught this faster. I kept thinking it had to be some missed unlock of the sbi->fs_lock, but it ends up its just the autofs4_lock. Apparently the conversion from using the dcache_lock -> autofs4_lock forgot that this function already grabs the autofs_lock for a small moment, so we end up grabbing the lock, then a moment later grab it again. Splat. This patch should resolve it. Signed-off-by: John Stultz diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 5b26088..a7eaa32 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -438,12 +438,10 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd) } /* Check for a non-mountpoint directory with no contents */ - spin_lock(&autofs4_lock); if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) { DPRINTK("dentry=%p %.*s, emptydir", dentry, dentry->d_name.len, dentry->d_name.name); - spin_unlock(&autofs4_lock); if (autofs4_need_mount(flags) || current->link_count) { int status;