Re: [RFC PATCH for -mm 1/5] mlock() fix return values for mainline

[Lee Schermerhorn <Lee.Schermerhorn@hp.com>]

On Mon, 2008-08-11 at 16:04 +0900, KOSAKI Motohiro wrote:
> following patch is the same to http://marc.info/?l=linux-kernel&m=121750892930775&w=2
> and it already stay in linus-tree.
> 
> but it is not merged in 2.6.27-rc1-mm1.
> 
> So, please apply it first.

Kosaki-san:

make_pages_present() is called from other places than mlock[_fixup()].
However, I guess it's OK to put mlock() specific behavior in
make_pages_present() as all other callers [currently] ignore the return
value.  Is that your thinking?

Lee
> 
> 
> 
> -----------------------------------------------
> 
> ---
>  mm/memory.c |   16 +++++++++++++---
>  mm/mlock.c  |    2 --
>  2 files changed, 13 insertions(+), 5 deletions(-)
> 
> Index: b/mm/memory.c
> ===================================================================
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2814,16 +2814,26 @@ int make_pages_present(unsigned long add
>  
>  	vma = find_vma(current->mm, addr);
>  	if (!vma)
> -		return -1;
> +		return -ENOMEM;
>  	write = (vma->vm_flags & VM_WRITE) != 0;
>  	BUG_ON(addr >= end);
>  	BUG_ON(end > vma->vm_end);
>  	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
>  	ret = get_user_pages(current, current->mm, addr,
>  			len, write, 0, NULL, NULL);
> -	if (ret < 0)
> +	if (ret < 0) {
> +		/*
> +		   SUS require strange return value to mlock
> +		    - invalid addr generate to ENOMEM.
> +		    - out of memory should generate EAGAIN.
> +		*/
> +		if (ret == -EFAULT)
> +			ret = -ENOMEM;
> +		else if (ret == -ENOMEM)
> +			ret = -EAGAIN;
>  		return ret;
> -	return ret == len ? 0 : -1;
> +	}
> +	return ret == len ? 0 : -ENOMEM;
>  }
>  
>  #if !defined(__HAVE_ARCH_GATE_AREA)
> Index: b/mm/mlock.c
> ===================================================================
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -425,8 +425,6 @@ success:
>  
>  out:
>  	*prev = vma;
> -	if (ret == -ENOMEM)
> -		ret = -EAGAIN;
>  	return ret;
>  }
>  
> 
> 

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