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SubjectRe: ext3 lockdep warning in 2.6.25-rc6
In message <20080402081215.GA2716@duck.suse.cz>, Jan Kara writes:
> On Tue 01-04-08 17:23:34, Erez Zadok wrote:
> <snip>
[...]
> I'll try to explain the locking here:
> 1) We are not allowed to call into __invalidate_mapping_pages() with
> inode_lock held - that it the bug lockdep is complaining about. Moreover it
> leads to rather long waiting times for inode_lock (quite possibly several
> seconds).
> 2) When we release inode_lock, we need to protect from inode going away,
> thus we hold reference to it - that guarantees us inode stays in the list.
> 3) When we continue scanning of the list we must get inode_lock before we
> put the inode reference to avoid races. But we cannot do iput() when we
> hold inode_lock. Thus we save pointer to inode and do iput() next time we
> have released the inode_lock...
>
> > Peter's post:
> >
> > http://lkml.org/lkml/2008/3/23/202
> >
> > includes a reference to a mail by Andrew which implies that the fix may be
> > much more involved than what you outlined above, no?
> Definitely we can do a more involved fix ;) What Andrew proposes would have
> some other benefits as well. But until somebody gets to that, this slight
> hack should work fine (Andrew has already merged my patch in -mm so I
> guess he agrees ;).

Thanks for the explanation. And good to know it's in -mm. I'll give it a
try.

Cheers,
Erez.


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