Hi guys,

On Mon, Dec 10, 2012 at 08:01:39AM +0000, Stephen Rothwell wrote:
> Today's linux-next merge of the akpm tree got a conflict in mm/memory.c
> between changes in commits from the tip tree and commit "mm: thp: set the
> accessed flag for old pages on access fault" from the akpm tree.
> 
> I fixed it up (I think - see below) and can carry the fix as necessary
> (no action is required).

[...]

> diff --cc mm/memory.c
> index 8022526,60201d5..0000000
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@@ -3812,15 -3620,18 +3812,17 @@@ retry
>                                                         pmd, flags);
>       } else {
>               pmd_t orig_pmd = *pmd;
>  -            int ret = 0;
>  +            int ret;
>   
>               barrier();
>  -            if (pmd_trans_huge(orig_pmd) && !pmd_trans_splitting(orig_pmd)) 
> {
>  +            if (pmd_trans_huge(orig_pmd)) {

This change worries me a bit wrt the huge_pmd_set_accessed function I
introduce below. Unfortunately, current -next doesn't seem to include it, so
I can't see whether do_huge_pmd_numa_page / do_huge_pmd_wp_page have been
changed to deal with the splitting or whether the check has been moved
earlier.

Will

> +                     unsigned int dirty = flags & FAULT_FLAG_WRITE;
> + 
>  -                    if (pmd_numa(vma, orig_pmd)) {
>  -                            do_huge_pmd_numa_page(mm, vma, address, pmd,
>  -                                                  flags, orig_pmd);
>  -                    }
>  +                    if (pmd_numa(*pmd))
>  +                            return do_huge_pmd_numa_page(mm, vma, address,
>  +                                                         orig_pmd, pmd);
>   
> -                     if ((flags & FAULT_FLAG_WRITE) && !pmd_write(orig_pmd)) 
> {
> +                     if (dirty && !pmd_write(orig_pmd)) {
>                               ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
>                                                         orig_pmd);
>                               /*
> @@@ -3830,10 -3641,12 +3832,13 @@@
>                                */
>                               if (unlikely(ret & VM_FAULT_OOM))
>                                       goto retry;
>  +                            return ret;
> +                     } else {
> +                             huge_pmd_set_accessed(mm, vma, address, pmd,
> +                                                   orig_pmd, dirty);
>                       }
>   
>  -                    return ret;
>  +                    return 0;
>               }
>       }
>   


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