On Wed, Jul 30, 2014 at 11:52:29AM +0200, Jan Kara wrote: > I see the problem now. How about an attached patch? Do you see other > lockdep warnings with it? This patch fixes the problem, thanks! Regardless of DAX, I think this patch should be applied in order to avoid creating a dependency between i_mmap_mutex and jbd2_handle. I've now run into a different problem with COW pages ... more later. > >From c01c905cf3c4c6304a5ea9836389d9cf0d575884 Mon Sep 17 00:00:00 2001 > From: Jan Kara <jack@xxxxxxx> > Date: Wed, 30 Jul 2014 11:49:07 +0200 > Subject: [PATCH] ext4: Avoid lock inversion between i_mmap_mutex and > transaction start > > When DAX is enabled, it uses i_mmap_mutex as a protection against > truncate during page fault. This inevitably forces i_mmap_mutex to rank > outside of a transaction start and thus we have to avoid calling > pagecache purging operations when transaction is started. > > Signed-off-by: Jan Kara <jack@xxxxxxx> > --- > fs/ext4/inode.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 8a064734e6eb..494a8645d63e 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3631,13 +3631,19 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length) > if (IS_SYNC(inode)) > ext4_handle_sync(handle); > > - /* Now release the pages again to reduce race window */ > + inode->i_mtime = inode->i_ctime = ext4_current_time(inode); > + ext4_mark_inode_dirty(handle, inode); > + ext4_journal_stop(handle); > + > + /* > + * Now release the pages again to reduce race window. This has to happen > + * outside of a transaction to avoid lock inversion on i_mmap_mutex > + * when DAX is enabled. > + */ > if (last_block_offset > first_block_offset) > truncate_pagecache_range(inode, first_block_offset, > last_block_offset); > - > - inode->i_mtime = inode->i_ctime = ext4_current_time(inode); > - ext4_mark_inode_dirty(handle, inode); > + goto out_dio; > out_stop: > ext4_journal_stop(handle); > out_dio: > -- > 1.8.1.4 > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>