linux-kernel - Re: lock held returning to user space (i_mutex_dir

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Date:	Thu, 12 Sep 2013 12:45:32 -0400
From:	Jeff Layton <jlayton@...hat.com>
To:	Dave Jones <davej@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: lock held returning to user space (i_mutex_dir_key)

On Tue, 10 Sep 2013 17:04:25 -0400
Dave Jones <davej@...hat.com> wrote:

> On Tue, Sep 10, 2013 at 05:02:37PM -0400, Dave Jones wrote:
>  > ================================================
>  > [ BUG: lock held when returning to user space! ]
>  > 3.11.0+ #64 Not tainted
>  > ------------------------------------------------
>  > trinity-child2/8333 is leaving the kernel with locks still held!
>  > 1 lock held by trinity-child2/8333:
>  >  #0:  (&type->i_mutex_dir_key#3){+.+.+.}, at: [<ffffffff811c7fce>] mountpoint_last+0x4e/0x1a0  
> 
> This perhaps ?
> 
> 
> -- 
> 
> Add missing unlocks to error paths of mountpoint_last.
> 
> Signed-off-by: Dave Jones <davej@...oraproject.org>
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 409a441..5a91474 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -2271,12 +2271,15 @@ mountpoint_last(struct nameidata *nd, struct path *path)
>  		dentry = d_alloc(dir, &nd->last);
>  		if (!dentry) {
>  			error = -ENOMEM;
> +			mutex_unlock(&dir->d_inode->i_mutex);
>  			goto out;
>  		}
>  		dentry = lookup_real(dir->d_inode, dentry, nd->flags);
>  		error = PTR_ERR(dentry);
> -		if (IS_ERR(dentry))
> +		if (IS_ERR(dentry)) {
> +			mutex_unlock(&dir->d_inode->i_mutex);
>  			goto out;
> +		}
>  	}
>  	mutex_unlock(&dir->d_inode->i_mutex);
>  

Well spotted.

Reviewed-by: Jeff Layton <jlayton@...hat.com>
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