Re: INFO: task mount:11202 blocked for more than 120 seconds

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From: David Chinner
Date: Sunday, March 16, 2008 - 1:33 pm

On Sat, Mar 15, 2008 at 12:58:02AM +0100, Christian Kujau wrote:

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

	do_something()
	enter memory reclaim
	iprune_mutex
	inode lock

or
	do_something()
	inode lock
	do_something_else
	enter memory reclaim
	iprune_mutex
	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....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group
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Messages in current thread:
INFO: task mount:11202 blocked for more than 120 seconds, Christian Kujau, (Fri Mar 7, 1:32 pm)
Re: 2.6.25-rc hangs, Eric Sandeen, (Sun Mar 9, 9:44 am)
Re: 2.6.25-rc hangs, Christian Kujau, (Sun Mar 9, 11:05 am)
Re: INFO: task mount:11202 blocked for more than 120 seconds, Samuel Tardieu, (Wed Mar 12, 11:03 am)
Re: INFO: task mount:11202 blocked for more than 120 seconds, Christian Kujau, (Wed Mar 12, 4:07 pm)
Re: INFO: task mount:11202 blocked for more than 120 seconds, Christian Kujau, (Thu Mar 13, 6:45 am)
Re: INFO: task mount:11202 blocked for more than 120 seconds, Christian Kujau, (Thu Mar 13, 2:54 pm)
Re: INFO: task mount:11202 blocked for more than 120 seconds, Christian Kujau, (Fri Mar 14, 4:58 pm)
Re: INFO: task mount:11202 blocked for more than 120 seconds, David Chinner, (Sun Mar 16, 1:33 pm)
Re: [dm-crypt] INFO: task mount:11202 blocked for more tha ..., Alasdair G Kergon, (Mon Mar 17, 10:36 am)