Re: [PATCH v2 01/13] mm: support madvise(MADV_FREE)

[Sergey Senozhatsky <sergey.senozhatsky.work-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi Minchan,

On (11/04/15 10:25), Minchan Kim wrote:
[..]
>+static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
>+                               unsigned long end, struct mm_walk *walk)
>+
...
> +	if (pmd_trans_unstable(pmd))
> +		return 0;

I think it makes sense to update pmd_trans_unstable() and
pmd_none_or_trans_huge_or_clear_bad() comments in asm-generic/pgtable.h
Because they explicitly mention MADV_DONTNEED only. Just a thought.


> @@ -379,6 +502,14 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
>  		return madvise_remove(vma, prev, start, end);
>  	case MADV_WILLNEED:
>  		return madvise_willneed(vma, prev, start, end);
> +	case MADV_FREE:
> +		/*
> +		 * XXX: In this implementation, MADV_FREE works like
		  ^^^^
		XXX

> +		 * MADV_DONTNEED on swapless system or full swap.
> +		 */
> +		if (get_nr_swap_pages() > 0)
> +			return madvise_free(vma, prev, start, end);
> +		/* passthrough */

	-ss