Re: [patch] pipe: Don't oops when pipe filesystem isn't mounted

[Andrew Morton <akpm@osdl.org>]

On Mon, 11 Dec 2006 03:27:37 -0500
Chuck Ebbert <76306.1226@compuserve.com> wrote:

> Prevent oops when an app tries to create a pipe while pipefs
> is not mounted.
> 
> Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
> 
> --- 2.6.19.1-pre1-32.orig/fs/pipe.c
> +++ 2.6.19.1-pre1-32/fs/pipe.c
> @@ -839,9 +839,11 @@ static struct dentry_operations pipefs_d
>  
>  static struct inode * get_pipe_inode(void)
>  {
> -	struct inode *inode = new_inode(pipe_mnt->mnt_sb);
> +	struct inode *inode = NULL;
>  	struct pipe_inode_info *pipe;
>  
> +	if (pipe_mnt)
> +		inode = new_inode(pipe_mnt->mnt_sb);
>  	if (!inode)
>  		goto fail_inode;
>  

That's pretty lame.  It means that pipes just won't work, so people who are
using pipes in their initramfs setups will just get mysterious failures
running userspace on a crippled kernel.

I think the bug really is the running of populate_rootfs() before running
the initcalls, in init/main.c:init().  It's just more sensible to start
running userspace after the initcalls have been run.  Statically-linked
drivers which want to load firmware files will lose.  To fix that we'd need
a new callback.  It could be with a new linker section or perhaps simply a
notifier chain.