Re: [PATCH] mm: fix do_mbind return value

[David Rientjes]

On Wed, 4 Mar 2015, Kazutomo Yoshii wrote:

> I noticed that numa_alloc_onnode() failed to allocate memory on a
> specified node in v4.0-rc1. I added a code to check the return value
> of walk_page_range() in queue_pages_range() so that do_mbind() only
> returns an error number or zero.
> 

I assume this is libnuma-2.0.10?

> Signed-off-by: Kazutomo Yoshii <kazutomo.yoshii@xxxxxxxxx>
> ---
>  mm/mempolicy.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 4721046..ea79171 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -644,6 +644,7 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
>  		.nmask = nodes,
>  		.prev = NULL,
>  	};
> +	int err;
>  	struct mm_walk queue_pages_walk = {
>  		.hugetlb_entry = queue_pages_hugetlb,
>  		.pmd_entry = queue_pages_pte_range,
> @@ -652,7 +653,10 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
>  		.private = &qp,
>  	};
>  -	return walk_page_range(start, end, &queue_pages_walk);
> +	err = walk_page_range(start, end, &queue_pages_walk);
> +	if (err < 0)
> +		return err;
> +	return 0;
>  }
>   /*

I'm afraid I don't think this is the right fix, if walk_page_range() 
returns a positive value then it should be supplied by one of the 
callbacks in the struct mm_walk, which none of these happen to do.  I 
think this may be a problem with commit 6f4576e3687b ("mempolicy: apply 
page table walker on queue_pages_range()"), so let's add Naoya to the 
thread.
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