Re: [PATCH 3/3] mm: call vma_adjust_trans_huge() only for thp-enabled vma

From: Andrew Morton
Date: Thu Feb 27 2014 - 16:23:59 EST


On Wed, 26 Feb 2014 23:39:37 -0500 Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote:

> vma_adjust() is called also for vma(VM_HUGETLB) and it could happen that
> we happen to try to split hugetlbfs hugepage. So exclude the possibility.
>

It would be nice to have a more complete changelog here please. Under
what circumstances does this cause problems and what are the
user-observable effects?

> --- next-20140220.orig/mm/mmap.c
> +++ next-20140220/mm/mmap.c
> @@ -772,7 +772,8 @@ again: remove_next = 1 + (end > next->vm_end);
> }
> }
>
> - vma_adjust_trans_huge(vma, start, end, adjust_next);
> + if (transparent_hugepage_enabled(vma))
> + vma_adjust_trans_huge(vma, start, end, adjust_next);
>
> anon_vma = vma->anon_vma;
> if (!anon_vma && adjust_next)
> --
> 1.8.5.3
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