lkml.org 
[lkml]   [2007]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 3/3] nfs: use ->mmap_prepare() to avoid an AB-BA deadlock
From
Date

On Wed, 2007-11-14 at 22:22 +0100, Nick Piggin wrote:
> On Wed, Nov 14, 2007 at 09:01:39PM +0100, Peter Zijlstra wrote:
> > Normal locking order is:
> >
> > i_mutex
> > mmap_sem
> >
> > However NFS's ->mmap hook, which is called under mmap_sem, can take i_mutex.
> > Avoid this potential deadlock by doing the work that requires i_mutex from
> > the new ->mmap_prepare().
> >
> > [ Is this sufficient, or does it introduce a race? ]
>
> Seems like an OK patchset in my opinion. I don't know much about NFS
> unfortunately, but I wonder what prevents the condition fixed by
> nfs_revalidate_mapping from happening again while the mmap is active...?

As the changelog might have suggested, I'm not overly sure of the nfs
requirements myself. I think it just does a best effort at getting the
pages coherent with other clients, and then hopes for the best.

I'll let Trond enlighten us further before I make an utter fool of
myself :-)

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-11-14 22:35    [from the cache]
©2003-2011 Jasper Spaans