linux-kernel - Re: [BUG][reiserfs] page fault during kernel boot

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Date:	Wed, 18 Aug 2010 00:20:14 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Marin Mitov <mitov@...p.bas.bg>
Cc:	linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [BUG][reiserfs] page fault during kernel boot

On Tue, Aug 17, 2010 at 11:25:25AM +0300, Marin Mitov wrote:
> Hi all,
> 
> The function: reiserfs_evict_inode() ends with:
> 
> <snip>
> out:
> 	end_writeback(inode);	/* note this must go after the journal_end to prevent deadlock */
> 	dquot_drop(inode);
> 	inode->i_blocks = 0;
> 	reiserfs_write_unlock_once(inode->i_sb, depth);
> 
> no_delete:
> 	end_writeback(inode);
> 	dquot_drop(inode);
> }
> <snip>
> 
> When goto out path is taken,
> 
> end_writeback(inode);
> dquot_drop(inode);
> 
> are executed twice, leading to page fault (in my case) during the kernel boot.


Indeed. More precisely it triggers a BUG in end_writeback():

	BUG_ON(inode->i_state & I_CLEAR);

that because we call it twice.

 
> Add return; before no_delete label (but I am not quite sure that this is correct :-).



That looks correct. 

Also Andrew Benton reported this issue and tested almost
the same patch and it seemed to solve the issue.

Thanks.



> Signed-off-by: Marin Mitov <mitov@...p.bas.bg>
> 
> ====================================================================
> --- a/fs/reiserfs/inode.c	2010-08-17 09:51:27.000000000 +0300
> +++ b/fs/reiserfs/inode.c	2010-08-17 10:45:20.000000000 +0300
> @@ -78,11 +78,12 @@ void reiserfs_evict_inode(struct inode *
>  		/* no object items are in the tree */
>  		;
>  	}
> -      out:
> +out:
>  	end_writeback(inode);	/* note this must go after the journal_end to prevent deadlock */
>  	dquot_drop(inode);
>  	inode->i_blocks = 0;
>  	reiserfs_write_unlock_once(inode->i_sb, depth);
> +	return;
>  
>  no_delete:
>  	end_writeback(inode);
> --
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