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SubjectRe: INFO: task mount:11202 blocked for more than 120 seconds
On Sat, Mar 15, 2008 at 12:58:02AM +0100, Christian Kujau wrote:
> On Fri, 14 Mar 2008, Milan Broz wrote:
> >Yes, there is bug in dm-crypt...
> >Please try if the patch here helps:
> Hm, it seems to help the hangs, yes. Applied to today's -git a few hours
> ago, the hangs are gone. However, when doing lots of disk I/O, the machine
> locks up after a few (10-20) minutes. Sadly, netconsole got nothing :(
> After the first lockup I tried again and shortly after bootup I got:

False positive. Memory reclaim can inverts the order of iprune_mutex and
the normal inode locking orders. i.e. Both of these are possible:

enter memory reclaim
inode lock

inode lock
enter memory reclaim
inode lock on different inode

So depending on what is seen first (in this case the first), the second
will trip lockdep. Neither are a deadlock, because the inode lock
held before memory reclaim is a referenced inode and will *never* be
on the free list for memory reclaim to deadlock on....


Dave Chinner
Principal Engineer
SGI Australian Software Group

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