Re: lockdep warning with 2.6.29-rc6-mm1 (mmotm 24-feb-2009)

From: Ingo Molnar
Date: Wed Mar 04 2009 - 12:42:00 EST



* Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Wed, 2009-03-04 at 18:27 +0530, Balbir Singh wrote:
> > I see the following on my machine. My understanding is that the
> > lockdep warning is complaining about a potential deadlock while
> > reclaiming, where we could end up waiting on holding inotify_mutex,
> > and we could end up calling reclaim with inotify_mutex held.
> >
> > The race seems rare, since one path shows a new inode being created
> > and the other one being deleted. It seems like a false positive unless
> > the inode's in question turn out to be potentially the same.
>
> Its not a false positive until you can guarantee the inodes will _never_
> be the same.
>
> This thing has been reported numerous times, Ingo even posted
> a potential fix for it, Nick poked the inotify people to speak
> up, but they have so far been silent on the issue :-(

that particular fix is upstream, via:

3023a3e: inotify: fix GFP_KERNEL related deadlock

so does this reproduce with latest .29-rc7-ish kernels too - or
do we have some other problem in this area too?

Ingo
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