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Re: [PATCH] xfs: Fix WARN_ON(delalloc) in xfs_vm_releasepage()

To: Ben Myers <bpm@xxxxxxx>
Subject: Re: [PATCH] xfs: Fix WARN_ON(delalloc) in xfs_vm_releasepage()
From: Jan Kara <jack@xxxxxxx>
Date: Mon, 18 Mar 2013 17:05:52 +0100
Cc: Jan Kara <jack@xxxxxxx>, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20130315205214.GB22182@xxxxxxx>
References: <1363267854-25602-1-git-send-email-jack@xxxxxxx> <20130315205214.GB22182@xxxxxxx>
User-agent: Mutt/1.5.20 (2009-06-14)
On Fri 15-03-13 15:52:14, Ben Myers wrote:
> Hi Jan,
> 
> On Thu, Mar 14, 2013 at 02:30:54PM +0100, Jan Kara wrote:
> > When a dirty page is truncated from a file but reclaim gets to it before
> > truncate_inode_pages(), we hit WARN_ON(delalloc) in
> > xfs_vm_releasepage(). This is because reclaim tries to write the page,
> > xfs_vm_writepage() just bails out (leaving page clean) and thus reclaim
> > thinks it can continue and calls xfs_vm_releasepage() on page with dirty
> > buffers.
> > 
> > Fix the issue by redirtying the page in xfs_vm_writepage(). This makes
> > reclaim stop reclaiming the page and also logically it keeps page in a
> > more consistent state where page with dirty buffers has PageDirty set.
> 
> Was there an easy way to reproduce this?  I'm testing and reviewing this now
> and it might help.
  I used scripts/run-bash-shared-mapping.sh from the attached tarball - it
fires up several processes beating a file with mmap accesses while
truncating the file and memory stressing the machine. I presume fsx with
some memhog could trigger the issue as well.

                                                                        Honza
-- 
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR

Attachment: ext3-tools.tar.gz
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