On Fri 04-04-08 11:37:58, Erez Zadok wrote:
> In message <20080325182909.GD21732@xxxxxxxxxxxxxxxxxxxxxxxx>, 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@xxxxxxx>
> > 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@xxxxxxx>
> > ---
> > 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@xxxxxxx>
SUSE Labs, CR
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