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Subject: Re: 2.6.15-git7 oopses in ext3 during LTP runs
From: Arjan van de Ven <arjan@infradead.org>
To: Andrew Morton <akpm@osdl.org>
Cc: ak@suse.de, linux-kernel@vger.kernel.org, sct@redhat.com, mingo@elte.hu
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Date: Wed, 11 Jan 2006 22:27:55 +0100
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> 15/fs/ext3/super.c~	2006-01-11 21:54:13.000000000 +0100
> > +++ linux-2.6.15/fs/ext3/super.c	2006-01-11 21:54:13.000000000 +0100
> > @@ -2150,7 +2150,7 @@
> >  
> >  static void ext3_write_super (struct super_block * sb)
> >  {
> > -	if (mutex_trylock(&sb->s_lock) != 0)
> > +	if (!mutex_trylock(&sb->s_lock) != 0)
> >  		BUG();
> >  	sb->s_dirt = 0;
> >  }
> 
> We expect the lock to be held on entry.  Hence we expect mutex_trylock()
> to return zero.

you are correct, and the x86-64 mutex.h is buggy

--- linux-2.6.15/include/asm-x86_64/mutex.h.org	2006-01-11 22:25:37.000000000 +0100
+++ linux-2.6.15/include/asm-x86_64/mutex.h	2006-01-11 22:25:43.000000000 +0100
@@ -104,7 +104,7 @@
 static inline int
 __mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
 {
-	if (likely(atomic_cmpxchg(count, 1, 0)) == 1)
+	if (likely(atomic_cmpxchg(count, 1, 0) == 1))
 		return 1;
 	else
 		return 0;

changes the asm to be the correct one for me.
This is odd/evil though..