Re: kernel BUG at lib/radix-tree.c:473!

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

On Mon, 2008-08-18 at 08:54 +0100, Ian Campbell wrote:
> On Mon, 2008-08-18 at 11:32 +1000, Nick Piggin wrote:
> > On Monday 18 August 2008 02:19, Ian Campbell wrote:
> > > FWIW the patch below apparently makes it work for me, but I'm not going
> > > to pretend I follow what's going on, why or what else it breaks ;-)
> > 
> > I think Iwould prefer fs_defio to use its own set_page_dirty
> > function. __set_page_dirty_no_writeback is supposed to be used
> > on pagecache, by filesystems.
> 
> fbdefio: add set_page_dirty handler to deferred IO FB
> 
> Fixes kernel BUG at lib/radix-tree.c:473.
> 
> Previously the handler was incidentally provided by tmpfs but this was
> removed with:
> 
>   commit 14fcc23fdc78e9d32372553ccf21758a9bd56fa1
>   Author: Hugh Dickins <hugh@veritas.com>
>   Date:   Mon Jul 28 15:46:19 2008 -0700
> 
>     tmpfs: fix kernel BUG in shmem_delete_inode
> 
> relying on this behaviour was incorrect in any case and the BUG
> also appeared when the device node was on an ext3 filesystem.
> 
> Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
> Cc: Jaya Kumar <jayakumar.lkml@gmail.com>
> Cc: Nick Piggin <nickpiggin@yahoo.com.au>
> Cc: Hugh Dickins <hugh@veritas.com>
> Cc: Johannes Weiner <hannes@saeurebad.de>
> Cc: Jeremy Fitzhardinge <jeremy@goop.org>
> Cc: Kel Modderman <kel@otaku42.de>
> Cc: Markus Armbruster <armbru@redhat.com>

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

> ---
>  drivers/video/fb_defio.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c
> index 59df132..214bb7c 100644
> --- a/drivers/video/fb_defio.c
> +++ b/drivers/video/fb_defio.c
> @@ -114,11 +114,23 @@ static struct vm_operations_struct
> fb_deferred_io_vm_ops = {
>  	.page_mkwrite	= fb_deferred_io_mkwrite,
>  };
>  
> +static int fb_deferred_io_set_page_dirty(struct page *page)
> +{
> +	if (!PageDirty(page))
> +		SetPageDirty(page);
> +	return 0;
> +}
> +
> +static const struct address_space_operations fb_deferred_io_aops = {
> +	.set_page_dirty = fb_deferred_io_set_page_dirty,
> +};
> +
>  static int fb_deferred_io_mmap(struct fb_info *info, struct
> vm_area_struct *vma)
>  {
>  	vma->vm_ops = &fb_deferred_io_vm_ops;
>  	vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
>  	vma->vm_private_data = info;
> +	vma->vm_file->f_mapping->a_ops = &fb_deferred_io_aops;
>  	return 0;
>  }
>  
> -- 
> 1.5.6.3
>