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    DateMon, 7 Apr 2008 13:47:58 +0200
    FromJan Kara <>
    SubjectRe: ext3 lockdep warning in 2.6.25-rc6
    On Fri 04-04-08 11:37:58, Erez Zadok wrote:
    > In message <20080325182909.GD21732@atrey.karlin.mff.cuni.cz>, Jan Kara writes:
    > 
    > > > I was building a kernel using "make -j 4" inside a unionfs, mounted on top
    > > > of ext3.  The kernel is vanilla 2.6.25-rc6 plus unionfs patches.  At some
    > > > point I forced a cache flush using "echo 3 > /proc/sys/vm/drop_caches" and I
    > > > got the lockdep warning below.  Note that unionfs doesn't appear to be
    > > > involved in this lockdep warning at all, so I suspect this is probably an
    > > > issue between jbd and ext3 directly.
    > > > 
    > > > Let me know if I can be of more help.
    > >   Actually, I have a fix for that - attached. Can you try it? Thanks.
    > > 									Honza
    > [...]
    > 
    > > From f5e41087e345fa5c3b46ac36e6e4a654d2f7f624 Mon Sep 17 00:00:00 2001
    > > From: Jan Kara <jack@suse.cz>
    > > Date: Tue, 18 Mar 2008 14:38:06 +0100
    > > Subject: [PATCH] Fix drop_pagecache_sb() to not call __invalidate_mapping_pages() under
    > > inode_lock.
    > > 
    > > Signed-off-by: Jan Kara <jack@suse.cz>
    > > ---
    > >  fs/drop_caches.c |    8 +++++++-
    > >  1 files changed, 7 insertions(+), 1 deletions(-)
    > > 
    > > diff --git a/fs/drop_caches.c b/fs/drop_caches.c
    > > index 59375ef..f5aae26 100644
    > > --- a/fs/drop_caches.c
    > > +++ b/fs/drop_caches.c
    > > @@ -14,15 +14,21 @@ int sysctl_drop_caches;
    > > 
    > >  static void drop_pagecache_sb(struct super_block *sb)
    > >  {
    > > -	struct inode *inode;
    > > +	struct inode *inode, *toput_inode = NULL;
    > > 
    > >  	spin_lock(&inode_lock);
    > >  	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
    > >  		if (inode->i_state & (I_FREEING|I_WILL_FREE))
    > >  			continue;
    > > +		__iget(inode);
    > > +		spin_unlock(&inode_lock);
    > >  		__invalidate_mapping_pages(inode->i_mapping, 0, -1, true);
    > > +		iput(toput_inode);
    > > +		toput_inode = inode;
    > > +		spin_lock(&inode_lock);
    > >  	}
    > >  	spin_unlock(&inode_lock);
    > > +	iput(toput_inode);
    > >  }
    > > 
    > >  void drop_pagecache(void)
    > 
    > Jan, I tried the above patch on top of v2.6.25-rc8-82-g49115b7, and using
    > the same setup and workloads that produced the warning before: running "make
    > -j 20" of the linux kernel 100 times, dual-CPU, SMP, PREEMPT, while running
    > flush_cache every few seconds.  The entire run took over 12 hours.  I'm
    > happy to report that so far I've not gotten the same lockdep warning as
    > before.
      Great news, thanks.
    
    > Maybe this can now go to -mm for more testing?
      Andrew has already merged it :).
    
    									Honza
    -- 
    Jan Kara <jack@suse.cz>
    SUSE Labs, CR
    
    
    
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