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Date: Sun, 2 Mar 2003 22:18:06 -0800
From: Andrew Morton <akpm@digeo.com>
To: Dawson Engler <engler@csl.stanford.edu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [CHECKER] potential deadlocks
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Dawson Engler <engler@csl.stanford.edu> wrote:
>
> BTW, are there known deadlocks (harmless or otherwise)?  Debugging
> the checker is a bit hard since false negatives are silent...

Known deadlocks tend to get fixed.  But I am surprised that you did not
encounter more of them.

btw, the filesystem transaction operations can be treated as sleeping locks. 
So for ext3, journal_start()/journal_stop() may, for lock-ranking purposes,
be treated in the same way as taking and releasing a per-superblock
semaphore.  Other filesystems probably have similar restrictions.

Other such "hidden" sleeping locks are lock_sock() and wait_on_inode().  The
latter is rather messy because there is no clear API function which sets
I_LOCK.

And pte_chain_lock() is a custom spinlock.


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