Messages in this thread | | | Date | Wed, 26 Mar 2008 09:28:20 +0800 | From | Fengguang Wu <> | Subject | Re: [PATCH] vfs: Fix lock inversion in drop_pagecache_sb() |
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On Tue, Mar 25, 2008 at 12:53:54PM -0700, Andrew Morton wrote: > On Tue, 25 Mar 2008 19:12:27 +0100 > Jan Kara <jack@suse.cz> wrote: > > > Fix longstanding lock inversion in drop_pagecache_sb by dropping inode_lock > > before calling __invalidate_mapping_pages(). We just have to make sure > > inode won't go away from under us by keeping reference to it and putting > > the reference only after we have safely resumed the scan of the inode > > list. A bit tricky but not too bad... > > > > Signed-off-by: Jan Kara <jack@suse.cz> > > CC: Fengguang Wu <wfg@mail.ustc.edu.cn> > > CC: David Chinner <dgc@sgi.com> > > > > --- > > 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; > > OT: it might be worth having an `if (mapping->nrpages==0) continue' here.
Good catch!
There are 25k opened inodes in my desktop, merely 10% of them has cached pages:
% cat /proc/sys/fs/inode-state 25395 129 0 0 0 0 0 # wc -l /proc/filecache 2542 /proc/filecache
+ if (!inode->i_mapping || !inode->i_mapping->nrpages) + continue;
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