Re: [PATCH 0/4] kill-the-bkl/reiserfs: fix some lock dependencyinversions

From: Frederic Weisbecker
Date: Tue Sep 01 2009 - 18:16:45 EST

On Thu, Aug 27, 2009 at 12:13:30AM +0400, Alexander Beregalov wrote:
> On Tue, Aug 25, 2009 at 04:32:46AM +0200, Frederic Weisbecker wrote:
> > Hi,
> >
> > This small set fixes some lock dependency inversions found in reiserfs
> > xattr and mmap paths.
> > I guess there are still some of them that I'll have to hunt, especially one
> > reported by Laurent Riffard and another one introduced by the reiserfs_readdir
> > path optimization (though I'm not sure about the latter, I have yet to find a
> > way to reproduce it properly).
> >
> > As usual, these patches can be found at:
> >
> > git:// \
> > reiserfs/kill-bkl
> Hi,
> possible circular locking dependency detected
> Is it false positive?

No, this confirms a real one, also the worst because it has been
introduced by a nice optimization (in term of result of throughput)
that I'll probably need to revert.

reiserfs_readdir() has a reiserfs_write_lock -> mm->mmap_sem
But reiserfs_readpage() has a mm->mmap_sem -> reiserfs_write_lock

I'll send a fix soon. Thanks a lot for this report Alexander!


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