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Message-ID: <1323863956.1954.50.camel@falcor>
Date: Wed, 14 Dec 2011 06:59:13 -0500
From: Mimi Zohar <zohar@...ux.vnet.ibm.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
Christoph Hellwig <hch@...radead.org>,
Dave Jones <davej@...hat.com>,
Linux Kernel <linux-kernel@...r.kernel.org>,
William Irwin <wli@...omorphy.com>,
Ingo Molnar <mingo@...hat.com>,
Tyler Hicks <tyhicks@...onical.com>
Subject: Re: hugetlb locking bug.
On Fri, 2011-04-15 at 14:27 -0700, Linus Torvalds wrote:
> On Fri, Apr 15, 2011 at 2:19 PM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > (Warning: whitespace damage and TOTALLY UNTESTED)
>
> Gaah. That won't work. Or rather, it probably may work, but while
> working it will spam the logs with that
>
> WARN_ON(!(inode->i_state & I_NEW));
>
> thing from unlock_new_inode.
>
> So the sane thing to do would be apparently one of
>
> (a) ignore the whole thing, and just accept the false lockdep warning.
>
> which I'd be willing to do, but it might be hiding some real
> ones, so we probably shouldn't.
>
> (b) just remove that WARN_ON(), and use the one-liner I suggested
>
> (c) extract the "set directory i_mutex key" logic into a new helper
> function for the case of filesystems like hugetlbfs that don't want to
> use unlock_new_inode() for one reason or another.
>
> Personally, I don't have any really strong preferences and would
> probably just go for (b) to keep the patch small and simple. Anybody?
>
> Linus
Since this discussion, commit "e096d0c lockdep: Add helper function for
dir vs file i_mutex annotation" defined a helper function
lockdep_annotate_inode_mutex_key(), but only hugetlbfs calls it. There
are plenty of other places where new_inode() is called without
unlock_new_inode() (eg. proc, devpts, debugfs, ramfs, ...). Is this
omission intentional or should they be annotated?
An incomplete patch was posted
http://marc.info/?l=linux-fsdevel&m=132369346810326&w=2
(Tyler Hicks' "vfs: Correctly set the dir i_mutex lockdep class" patch
http://marc.info/?l=linux-fsdevel&m=132370587315054&w=2 should be
prereq'ed.)
thanks,
Mimi
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