From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andi Kleen <andi@firstfloor.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-kernel@vger.kernel.org, Trond.Myklebust@netapp.com
Subject: Re: NFS lockdep lock misordering mmap_sem<->i_mutex_key with 2.6.32-git1
Date: Tue, 15 Dec 2009 22:21:34 +0000 [thread overview]
Message-ID: <20091215222134.GA27892@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20091207132009.GI18989@one.firstfloor.org>
On Mon, Dec 07, 2009 at 02:20:09PM +0100, Andi Kleen wrote:
> > nfs_readdir
> > nfs_do_filldir
> > filldir
> > copy_to_user
> > [page_fault] [grab mmap_sem]
> >
> > sys_mmap [grab mmap_sem]
> > do_mmap_pgoff
> > mmap_region
> > nfs_file_mmap
> > nfs_revalidate_mapping
> > nfs_invalidate_mapping [grab i_mutex]
> >
> > I guess recent lockdep improvement find old bug.
>
> Thanks for the analysis.
>
> I guess should never do copy_*_user while holding i_mutex? There might
> be lots of cases like that.
No. mmap_sem inside i_mutex is the normal order; NFS mmap is doing the
wrong thing here. Note that readdir() vs. NFS (file-only, thankfully ;-)
mmap() is a non-issue; NFS mmap() vs. write() is much more interesting.
Again, a lot of mm/* code expects i_mutex, then mmap_sem order. It's not
just readdir().
next prev parent reply other threads:[~2009-12-15 22:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-07 11:59 NFS lockdep lock misordering mmap_sem<->i_mutex_key with 2.6.32-git1 Andi Kleen
2009-12-07 12:19 ` KOSAKI Motohiro
2009-12-07 13:20 ` Andi Kleen
2009-12-07 17:38 ` KOSAKI Motohiro
2009-12-07 17:38 ` KOSAKI Motohiro
2009-12-15 22:21 ` Al Viro [this message]
2009-12-15 23:38 ` Andi Kleen
2009-12-15 23:54 ` Trond Myklebust
2009-12-16 0:09 ` Al Viro
2009-12-16 13:16 ` Trond Myklebust
2009-12-23 16:32 ` Andi Kleen
2009-12-16 0:53 ` Andi Kleen
2009-12-16 13:09 ` Trond Myklebust
2009-12-16 15:57 ` Andi Kleen
2009-12-16 0:06 ` KOSAKI Motohiro
2009-12-16 0:48 ` Andi Kleen
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